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IAT Resistor Mods vs Performance Modules vs Real Chips

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IAT Resistor/Modules Vs. Performance Chips

IAT Modification Scam - Do not bite this bait!

real eprom chipFake Module 1Fake Module 2Fake Module 4

Fake Module 5Fake Module 3

What are those infamous IAT resistor mods and performance modules and how do they compare with real EPROM racing or performance chips? Need a guide to try it out by your self? Find out here…

What are performance chips (Real EPROM or ROM Chips)?

Some facts:

Chips = Memory Chips = EPROM or ROM (Erasable/Programmable Read-Only Memory)
ECU = Car Computer (Engine Control Unit)

Just like your PC, car computers or ECUs have a CPU (Microprocessor or Microcontroller), RAM memory and a boot device. In their case, EPROM chips serves as the boot device, instead of a hard disk. These EPROM chips contain the ecu’s operating system and operating parameters data, and hold it even if the power is removed from the ecu for any amount of time, even years, due its internal architecture.

Real EPROM chip 2<– Real EPROM Chip

These EPROM chips were used on Non-OBD (1988-1991) and OBD-I (1992-1995) cars. In the case of the newer OBD-II cars (1996 and later), manufacturers use a different approach, being either an EEPROM (also called E2PROM) or (more commonly) FLASH ROMs. Both methods are very similar to an EPROM device type, but with newer features, like on board re-programming for example. All types of these ROM, EPROM, EEPROM and Flash memory chips, or simply “chips”, are called memory chips and so we will call them in the rest of this article.

Once you put your car key to “ignition” or “on” position, it powers up the ECU, among some other circuits, and right after it is powered up, it immediately boots from the memory chip and reads the operating system from it, which is the program that will run and control the ecu itself and the engine. It does things like reacting or responding to the various sensor readings. The ECU will also read from the same memory chip, the parameters data, which is the data that will tell the ecu how much fuel to inject, how much ignition timing to apply, what to do if the engine is hot or cold, etc.

What changes these real chips do:

When an aftermarket memory chip is installed in your car’s ECU, you are changing the program or operating system running it. It could be either slight changes or a major reprogramming, depending on the intended purpose and the chiptuning Company. The new parameters programmed on that new memory chip will hopefully affect the behavior of the ecu and its response to the different signals received from the various engine sensors in a positive way, aimed in the direction of more power, or to accommodate new engine hardware like a Turbo system, aftermarket camshaft, or any other modification that require an ECU reprogramming. The result will be a change in performance that will depend on the program written in the chip.

Some of the changes done to these aftermarket memory chips are (1) disabling the vehicle speed limiter or governor, allowing the vehicle to reach its maximum natural speed, (2) the RPM limiter or revlimiter is slightly raised, allowing higher engine speeds for an extra punch when shifting and (3) the fuel and ignition tables (maps) are are changed or “remapped” for optimum fuel delivery and ignition firing.

Chip Tuning Software

What about the IAT resistor kit, IAT mod, etc?


IAT Sensor = “Intake Air Temperature” sensor
AFR = Air/Fuel ratio, ideally it would be 14.7 units of air to 1 unit of fuel or 14.7:1 (lambda 1)

The IAT sensor is a passive or discrete electronic component that will simply vary its resistance depending on changes in temperature (also called a thermistor). It has a negative coefficient, meaning that the higher the temperature is, the lower the resistance it will offer to the current flow and vice versa.

Different IAT sensors (external to the MAF):

IAT Sensor 1IAT Sensor 2

When a voltage is applied through a resistive network (shown below) of which the IAT sensor is part of, the output voltage from that network (“To ECU” in the drawing) will vary or “swing” according to the temperature of the air passing through the IAT sensor. This swing is caused by the mentioned variation of resistance of the IAT sensor, that at the same time causes variation in voltage drop. The voltage fluctuation at the output of the resistive network will be interpreted by the ECU as a direct reading of incoming air temperature variation.

IAT Equivalent Circuit

So why the ecu needs to know the incoming air temperature?

The answer is a simple fact of physics. Cold air is denser than hot air, having higher mass by volume, meaning more oxygen content. The importance of this, is to allow the ecu to modify the Air/Fuel Ratio (AFR) to acceptable levels, so combustion inside the engine can be kept at optimum levels, allowing optimum engine power, preventing engine from knocking and having lower nitrous oxides (NOx) emissions. It helps to the understanding of this, knowing that a mixture of air and fuel (gasoline in this case) will only be highly flammable at certain proportions. Too much air, too explosive. Too much fuel, will burn too slow or won’t ignite at all. The engine will theoretically need around 14.7 grams of air to every gram of gasoline.

The modification:

Few ECUs will use the signal from the IAT sensor alone, to modify the ignition and / or injection to slightly compensate for the incoming air temperature variations. So making the computer “think” the incoming air is cold will make it do small adjustments to ignition timing and / or fuel injection and there is where the IAT Mod ideal originally came from.

It is accomplished by putting a fixed resistive value (fixed resistor) instead of the regular IAT sensor, simulating a cold intake air situation. Going back to the facts above, “the higher the temperature, the lower the resistance”, to benefit form this modification, we would need to make the resistor value high enough to make the computer “think” that the temperature is low enough. That would hopefully induce the ecu to inject more fuel and advance ignition timing accordingly, in an attempt to compensate the supposed incoming cold air.

Resistor Inserted in the IAT Connector

The problem with the IAT modification:

Even more and more people that have bought those IAT mods are claiming that it does nothing. It is probably attributed to the fact that not all cars depend only on the IAT sensors alone to make the necessary changes. So, it is very probable that modifying the IAT sensor of your car will do nothing, or at least nothing noticeable.

If you successfully modify the IAT sensor and the engine makes some noticeable changes, remember that the air will not be truly colder or denser, so no extra oxygen will really be present, ending up in a richer mixture, higher emissions and very probably lower performance, unless your car is already running way too lean because any previous modification or any existing engine problem and a richer mixture will benefit its performance.

If you live in a cold area, you will notice no difference as the original IAT sensor installed in your car will already be in a better resistance value than the one you would insert. If you live in a hot area (tropic, desert), it will be worse than the ones in a cold area, as even less oxygen will be available for the combustion. If you live in a high altitude area, you will have similar or worse luck that the ones in the hot areas as oxygen and pressure progressively decrease with altitude, even if it’s cold.

Regardless of the all mentioned above, if you finally make the car computer do a positive modification by installing that 10 cents resistor, remember that changes will be on the factory program range limits or specifications anyway, as the chip or computer program is still the factory installed one. All changes made by sensor modifying (any sensor), will stay in the factory specs since sensors can be read but can not bypass or override functions in the ECU, unless a memory chip with a modified program (performance chip) is installed.


Simple Resistor

Don’t take my word!!!

Please, don’t just take my word about this. You can experiment it yourself if you are a little skeptic about this or just want to try it (I would do). 🙂

Do it your self:

All IAT sensors resistance, average from about 4700 to 5000 ohms (4.7K-5K) when the air temperature is cold enough to make an adjustment on ignition timing and / or fuel injection. The trick is to replace the IAT sensor by a resistor with a “cold temperature” equivalent resistance value, similar to those mentioned above.

NOTE: For easy calculating the resistor you need, just use the online resistor color code calculator: Resistor Color Code Calculator

All IAT sensors have two wires, but though many of them are installed alone in the incoming air path elsewhere after the air filter, some of them are incorporated inside the MAF (Mass Air Flow) sensor assembly. In that case, the MAF sensor connector will have 4 or 5 wires, where 2 of them will be connected to an internal IAT sensor. You will either need to find the stand alone IAT sensor in the incoming air path or identify the wires connecting to it on the MAF sensor connector if it is internal.

In the first case, the installation is done by disconnecting the plug to the IAT sensor and inserting the resistor leads, making contact with the IAT sensor plug connections (the part that goes to the ECU and NOT the part that goes to the sensor).

How IAT Resistor is Installed

In the internal IAT sensor case, you will need to cut the two wires that connects to the internal IAT sensor to some length, to attach the resistor. Using the picture bellow as reference, if for example the IAT sensor is connected to wires 1 and 3, you should cut where the two green crosses (“X”s) are in the picture and attach, either by soldering or by using wire nuts, the fixed value resistor you chose for your car at the pair of wires that go to the “ECU” direction. You must cover the other remaining two cut wires with electrical tape or better, with a terminator connection for protection. Please note that the below example is just that, an example. Wires connecting to the internal IAT sensor can be any on every different MAF type.

MAF with internal IAT sensor

You will be able to easily locate the internal IAT sensor by looking at the picture below. This will help in (1) knowing where to spray with the component cooler can when measuring for best value and (2) you can determine what wires are connected to it by using an ohmmeter, measuring between the IAT sensor leads and the connector wires.

Identifying MAF internal IAT sensor

Remember, you will electrically replace, but not physically replace the IAT sensor. That is, you will connect the resistor to the cables going to the ecu, but will leave the sensor in its place. The resistor, the same as the IAT sensor, has no polarity. That means that you can connect either wire with either resistor lead.

Now, since the resistor has a fixed value and the IAT sensor is out of the circuit, resistance will no longer vary with temperature. The car computer will permanently think that incoming air is very cold as long as the modification is in place.

After connecting the resistor, just make sure it is covered with tape or any other insulator and you can leave it hanging in a safe area on the engine bay as long as it doesn’t receive too much heat.

Now just do a test drive. How was it? Anything? No? No problem, you are not the only one. 🙁

Extra info:

As mentioned before, the resistance values of the IAT sensor averages between 4.7k – 5k, but if you want to try the exact optimum value for your car, just take out the IAT sensor, if it is the stand alone version of course, and put it in an ice bath prepared in glass or cup. Leave it submerged for 1 or 2 minutes and measure the resistance across the two connecting wires or terminal with an ohmmeter, preferable a digital one, in the 20K or equivalent range.

The measured resistance will be the optimal for your car. Probably you won’t find an exact commercial value that matches the measurement, but you can get the closest one. For example, if it measures 4633 ohms, then a 4700 ohm (4.7k) is a very common commercial value and will do the job just fine. Color rings for a 4.7K resistor will be Yellow – Purple – Red with either a Gold or Silver fourth ring. Check on Google for other resistor values color code if need any other value; Key word = “Resistor Color Code”.

If your IAT sensor is the MAF type (5 wires) you can not submerge it as it will be damaged, but you may find a component cooler spray sold for electronic circuits thermal troubleshooting and spray it directly over the IAT sensor inside the MAF assembly and then measuring it with the ohmmeter before it warms back up. The only thing is that such spray will go lower in temperature than a simple ice bath.

Freezing spray

Make sure that the MAF sensor is completely dry before installing it back, since cold spraying it will make some condensation moisture.

Now do the test drive.

I know, probably it was the same or worse. That is the result of 90% of the cases. The remaining percentage? Well, an 8% is placebo effect and the other 2% maybe people that succeed in putting fourth of an extra horsepower (1/4 hp) and are content with that.

What about those mysterious boxes called performance modules?

Fake Performance / Racing / Speed Module 1Fake Performance / Racing / Speed Module 2Fake Performance / Racing / Speed Module 3

Those shiny small boxes called “performance modules” that comes for a variety of models and model years, mostly with 4 wires coming out of it or even with a power select switch or rotary power control are the same cheap resistor, boxed, given fake attributes and some of them added a fancy control (variable resistor or potentiometer) along with the fixed resistor or a switch to select from different resistor values or “power ranges”.

People no longer wanted to buy a 10 cents resistor for $15-$70, so they boxed it to make it look cool and hide it at the same time to avoid recognition, making people think that it is something way much more sophisticated than a simple, cheap and most of the times, non working resistor. Some sellers went farther than that, making people believe that the resistor was “tuned” specifically for your car model. There is no way of tuning a fixed part! Others use a resistor network chip and wire two of the leads to the outside of the box. Those chips are not semiconductors or anything alike. They just have several internal resistors in parallel of the same resistance value to save space in circuits. They just hook one of the internal resistors to the IAT.

The results, the same of the resistor alone… NOTHING!


Many people is asking me about what’s inside of the adjustable boxes. The truth is that it is all the same and results won’t change, but to satisfy everybody’s curiosity, they just add a variable resistor or “potentiometer”.

It is used to adjust the total resistance of the circuit. That is, instead of having a fixed 4.7K resistor as a total and absolute value, it is made adjustable by placing a potentiometer in series with the circuit.

Below is an example of this. In this picture, it is shown both pictorial and schematic versions for better understanding, along with direction of maximum and minimum resistance.

This time it is selected a resistor with lower value to be fixed as the minimum circuit value. That is, if the person doing the scam knows what he is doing.

In this case, minimum resistance will be the value of the fixed resistance, which is 220 ohms (equals to hot incoming air) and can be adjusted by turning the potentiometer all the way up to the sum of both resistors, which in this case will be 220+10,000 ohms = 10220 ohms, making it equivalent to very low temperatures.


Well, I don’t know about you, but I think this can called “IAT Module Demystified”…

You are welcome to leave comments.

Thanks for reading,


For real performance chips (not resistors) that will make your car pull real hard, visit the page below:

These are real and tested. Trust us when we are saying that you won’t find anything alike on internet. We will soon post about the truth about big chip companies. Keep “tuned”.

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Trackbacks & Pingbacks
December 10, 2008

I often see questions and search engines results, stating “are performance chip just resistors?”. In this post you will find out that the answer is -no-. Real sellers sell real chips and then, there are the other ones.

Sometimes, “Performance Chips” is just a nice name that some people put on an item for successfully selling it.

Imagine someone trying to sell a “racing resistor”.

A lot of people get disappointed when they pay some amount of money and are excited when it finally arrives to their mail box, only to find out that they have been “ripped off” with a nice box with a resistor inside.

I personally bought one once from an online store and it didn’t even was enclosed in a box. It was a simple resistor in an envelope, with a very hard to read black and white blurred instructions sheet… well, you can imagine what an unpleasant feeling it was and how angry I became with my self…

I personally run an eBay store and offer real chips. At the moment we have only several chips and services, but we are expanding step by step. You may ask any question you have about any of the items or services on the store.


December 17, 2008

Hey thanks for the info! You saved me some money. I was about to buy one of those “modules” when I found your article.



PostedbyFrank Montero
December 22, 2008

I have also seen questions like: “is it safe to put an ait sensor module in your car”

The answer is yes. Trying it won’t hurt your ecu or engine. There is no too low or too high of a resistance value that will hurt any of both. Just avoid shorting the connector with other sources like ground or + battery terminal.

January 24, 2009

hello i bought a “performance modules” it is cost me 120 dollars and a time i break and only had a f**k it resistor of 1 cent dont buy that peace of s**t much better go to radio sack and buy a 5 resistor by a dollar and its work the same ok bye

January 24, 2009

Yes. That is the result that is often obtained from those “modules”. Just take a look inside that box and you will see the sophisticated circuit of just one resistor…

January 26, 2009

Thanks for the info, works great!

PostedbyArten Rozorf
February 3, 2009

Love the advice. Thank you.

February 7, 2009

Thank you for sharing. I came to this site to read how things really are

March 21, 2009

We will post soon a follow up of this info, based on requests made by visitors. Just use the search at the top of this page to check if it is available yet.
(search for IAT, etc.)

Thanks to you all for reading.


March 21, 2009

Man I did it myself and didnt worked no matter what value in ohms i used. These guys at ebay selling resistor for a lot of bucks r some clowns. poor them who buy from them.

PostedbyLouis Penn
March 21, 2009

I am glad this information is helping people to not get into a scam.

By the way, the additional information was already published at:

April 21, 2009

has anyone tried a resistor in a Honda civic

April 22, 2009

2007 vw caddy tdı resistor what ohm ???

Postedbymehmet ozcan
April 22, 2009


April 22, 2009

Hello Mehmet. Resistance of most VW’s IAT run considerably lower then other makes. It is as follows:

86F(30C) – 1.5k – 2K
104F(40C) – 1K – 1.5K
122F(50C) – .8K – 1K
140F(60C) – .5K – .7K
158F(70C) – .3K – .5K
176F (80C) – .27K – .37K
194F (90C) – .22K – .27K

All values are in K-ohms (x1000 ohms), so for example, 1.5K = 1500 ohms and .27K = 270 ohms.

Good luck.

April 22, 2009

Hello J.

I hope someone that have tested it on a Civic can post his or her experience here. Myself, i haven’t tried on Civic, as I use chips for Civic (if it’s OBD-I), but tested on Mazda Protege, Hyundai Scoop and Accent, GM Cavalier and Ford Taurus, among some others and haven’t noticed anything.

But of course, as i said, it will be nice if others post their experience.

April 24, 2009

OHM ???

April 24, 2009

Mehmet, you may look at the information in the table for VW above. If I was doing it for a VW, I would use 2.2K-Ohms for simulating colder than 86F(30C). The color code would be -red,red,red,gold.

May 13, 2009

I was told you can connect a 20 k adjustable resistor pot in parallel to the original car IAT to retard the timing is it true?
I am running hho(hydrogen)and I want to retard the timing.

May 15, 2009

Hello Nikolas. If your car is one of the models that ONLY take the IAT sensor input to make changes, AND, those changes made are in both the fuel and timing areas, then yes, an adjustable or any other resistor in PARALLEL with the IAT (with the IAT in the circuit, NOT disconnected), will make the resistance value to go down, making the ECU “think” that the incoming air is hotter, lowering the fuel being injected and retarding ignition (in fact, not retarding, but advancing less than normal) in an attempt to avoid detonations that would happen if the temperature would be truly hot.

You will also feel a loss in power due to that, so if you feel the loss, then the resistor is doing the job.

The fact that it is an adjustable resistor (potentiometer or just “pot”), you can play with it to bring it to different resistance values. The lower the total resistance in the circuit, the less advance it should apply.

As for the potentiometer, I think that using 20K for that purpose is in the right track, since that value would cover 99.9% of the values presented in an IAT sensor.

As a final comment, as you mentioned that are using HHO, please note that as noted above, the fuel injected will also be less. I mention that just in case you are counting on the actual fuel supply and haven’t consider a variation (injection).

Best regards and Good luck.

May 16, 2009

what about those modules connectting to the obd port? cuz im looking at one right now well actually still because you went into great detail of replacing your ecu or (not) gettin a iat resistor online but wat about the obd port mods?

May 16, 2009

Well, if you refer to modules like the one offered by Superchips, for example (Micro Tuner), they do work as they are a completely different approach. Instead of being a plain resistor, they are complete hand-held micro computers, each one programmed for specific cars.

Those modules are a real solution for performance, but are a bit expensive ($200 – $500)

They connect to the ecu through the OBD-II (diagnostic) port and reprogram (flash) the internal memory, inserting a performance program. It will be the same as installing a performance chip in your ecu, with the exception that such modules often offer a menu with different performance levels to choose from.

It is done through the diagnostic port because most 1996 and newer vehicles did not come with a replaceable chip on their circuits. Instead, it is re-written this way.

With those modules, still assuming we are talking about the same modules, performance varies from manufacturer to manufacturer. One good thing is that it stores in memory the original contents of your ecu, in case you wish to go back to stock mode. You may go from performance to stock and back as many times you wish, as long as it is used in your vehicle.

Once you connect it to your vehicle and perform the first programming, the VIN number or any other code is automatically stored on the device for it to identify your vehicle.

If the modules I described are not the ones you refer to, just reply to this thread with details so I can help you better.



May 21, 2009

simple things i have a 1.4 honda civic 98 with 75HP’s from its mother i did those modifications :

i have a cold air intake + 6-10HP
final exaust system + 3-7HP
iridium sparks +1-2 HP
IAT sensore RESISTOR makes the cold air intake’s gain +2-4 HP to the excisting values
2 neodmium magnets + 2-4 HP’s(ionizers)
now my car is 97 HP’s tested ! i don’t need to reprogramm my ECU because i gained 22 HP’s without touching it.!!!

one more thing DO you know that the Catalysts in all cars REDUSES the Horsepower from 6-10 HP’s ??? if u have the money go buy aftermarket ‘racing’ and you’ll see the diffirence

May 22, 2009

Well, I’m glad you obtained all that extra power without even reprogramming the ecu. It would be nice to look at the Dyno charts before and after the mods.

I guess you have the charts, since you stated that gains were tested. Also, are the mentioned gains in BHP (engine) or WHP (wheels)? Not contradicting you, I just would love to know the details. That way, more people can take advantage of the tricks.

As you mentioned, your car is 1.4L, so I guess it is a Diesel model. Since this website is mainly oriented to gasoline models, I can not comment on this and will be open for discussion for Diesel savvy people.

Thank you very much for your comments.

Best regards,


May 22, 2009

No it isn’t diesel is gazoline and is only 1.4 lt . this model is from germany and i live in greece i don’t have the dyno test but the 97HPs (96,73) exactly are true i tested on my friends dynamometer and is WHP not BHP.
i can only tell u this from stop 600 meters race with a VW polo 2000 1.4lt with 101HPs from its mother- i am 2 cars ahead and i tested at least 3-4 times before the modifications i was 2 cars back.
as for the details
i will inform you soon when i make the details 🙂 thanx

May 22, 2009

Nice! About the cold air intake, as you may know by now, the cooler, the best. If using a metal runner on the ram air intake, it will work even better if you insulate it with a heat resistant material like that used on air conditioners that is made of foil and glass fiber. The less heat the runner absorbs from the engine, the cooler the air will enter the engine and since cooler air has more oxygen concentration, will turn in even more power!

I know, not too aesthetic as a chrome metal runner, but will perform better.

Will look forward for the info. Thanks for sharing it!

Best regards,


June 4, 2009

So then: These ‘2cent’ resistors will(not:-[) work on a Diesel?
Not aware that similar criteria applied to CompIgn fuelling… Live & Learn :<)

June 11, 2009

Hi all,

I have bought a “Performance Chip” (it is a box with 2 wires coming out – look like there is only a resistor inside) on EBAY with the price of $24.99 and it is wonderful. My car is running smoother and faster, look like it is gaining horse power too. I really love it. Here is the one that I bought:

If you don’t know how to connect, ask the seller (send him an email and he will answer within 48 hours)

The only thing I has changed from instruction that instead using the clip to connect the wires, I sliced out the wires and connecting them to make sure that they have a good contacts with each other. PERFECT.

PostedbyFriendly Guy
June 11, 2009

Hello Friendly Guy. It is good that you bring this to discussion here. The product you describe is exactly that, a simple resistor inside a box.

Sellers are just learning about that scam and repeating it again and again. As long as there are people buying their lies, they will continue doing this.

Could you imagine? Not enough with the extra horsepower scam, now they add that it will save fuel!!!. How in the world can it save fuel if it is injecting more fuel in the case that it would work???

I am an Electronics / Automotive technician and I posted here the truth about those resistors scams so people have the opportunity to make the right choice between the reality and being scammed.

No offense, and if you feel it works, nice for you, but sure you haven’t tried a real chip or a real tuning.

From the same seller, here are some people that think different than you do, just to list a few. This was taken from his feedback history and the common answer from him to all those buyers is “you did an incorrect install”

It is part the buyer and part the people that keep sponsoring such actions by buying his fake products. It make it seems like performance doesn’t matter any more, but how much they lie and how good the fake product looks, which will boost the placebo effect.



FEEDBACK: Item never left your store.Confirmed by USPS.Lied about shipping it 2 times.Poor

FEEDBACK: Item simply not peformaned as advertised, Other feedback implies mine is not odd

FEEDBACK: got no change in hp,worked with cus. ser. & still no change.inst. rite 2!

FEEDBACK: e mailed sellerto ask for wiring digram no response tryed three times.

FEEDBACK: the company knows the device may not work on all vehicles as advertised. bummer

FEEDBACK: no mpg +, slight performance +,21 days, engine missing,stalling,device removed

FEEDBACK: never got my item ,seller woul not responds false tracking number

FEEDBACK: It did’t work in my car I still have it instald and I still hevent seen a change

FEEDBACK: fast shipping/answered questions/product does not work for our car/can return
Follow-up – beware of this seller/false nonpayment strikes if not 100% positive feedback!!!!

FEEDBACK: fast shipping just havent notice any power gain yet maybe to early????

FEEDBACK: Doesnt do what they claim, even after I hooked it up right

FEEDBACK: doesn’t do anything special

FEEDBACK: The delivery was good and quick, but the installations manual was not good.

Follow-up – aviod this seller. car NOT modified. seller makes false claims about no paymnt

FEEDBACK: Chip is a ripoff there is nothing in the box couln’t get to work so i checked

FEEDBACK: did’nt work on my other truck, Wnot waste the time installing it on this one

FEEDBACK: Opened it up, 2 wires connected to a resistor, 25¢ item for $25, total crap

FEEDBACK: SHENANIGANS – a secret, dishonest activity or maneuvering

FEEDBACK: tried all the suggestions cannot tell any difference with or without it!

FEEDBACK: fast shipping, but what I paid for was a product that just simply did not work

FEEDBACK: no power or mpg gain at all

FEEDBACK: I have not noticed anything after putting this chip on my car.

FEEDBACK: I have had no real hp gains or noticed any help for my fuel economy?

FEEDBACK: item sucks. had for two weeks and still nothing. garbage!!!!!!!!!!!!!!!!!!!!!!!!

FEEDBACK: it did nothing they said it would do, no horsepower gains and no mpg increase

FEEDBACK: this gas saver is a joke! its only a wire in a plastic box! you get what you pai

FEEDBACK: didnt really make a diffrence

FEEDBACK: Fraudulent product; No Difference on my truck

FEEDBACK: change, just a couple of wires..shipped fast, just no performance.



FEEDBACK: All hooked up, correct ! dont feel any performance gains as yet, we will see…

FEEDBACK: Took seller 4 weeks to refund my money so i can revise my feedback…

FEEDBACK: Biggest ebay scam ever. Open it up and look inside people!

June 11, 2009

Hi Admin,

I have an Lexus 2003 ES300 and it was a little weak before when trying to accelerate from a stop or in motion. The mileage on my car before was about 17mpg in the city and around 30 mpg in the highway. Since I would like my car to be a little faster and I saw the seller has a lot of good feedback (almost 100% at the time I bought the device 2 months ago) so I would like to give my car a try. It works, however, the mileage is now look like fixed at 20-22 mpg even in the city or highway and I have not been driving far on the trip like several hundred miles so I did not know if the mileage will improve, but so far I can see that my car is quicker and faster but I don’t know if it will cause any air pollution since as you have said it pumps more gas to the engine. Thanks.

PostedbyFriendly Guy
June 11, 2009

Hi Admin again,

Do you know where can I buy the Real Chip for my 2003 Lexus ES300 so I can take out the Mod Performance Chip that I bought on EBAY?

I have been looking for the Real CHIP before but I did not see anywhere selling it.

The city I live now (San Jose, CA) is having too much traffic and people are driving a little fast so it is a little scare when my car can not going a little faster.


PostedbyFriendly Guy
June 11, 2009

Thanks for your comments and contributing to the topic. I really appreciate it.

By the way, in your case, that you had a positive experience, I guess that you may use the information on this page to maybe try to do a “fine tuning” by trying different resistance values.

The values for the 2003 ES300 are:

-4F (-20C) = 13,600 – 18,400 Ohms.
-68F (20C) = 2,210 – 2,690 Ohms.
-140F (60C) = 493 – 667 Ohms.

That way, serving to the purpose of this article, if someone is to benefit from this, he or she can do it for free, or at least for the very small cost of a resistor (without the box which only purpose is for disguising/making attractive).

By the way, on this model, the IAT is embedded inside the 5-Connector MAF sensor, wired to #4 (BLUE w/ BLACK) and #5 (BROWN).

Best regards,


June 12, 2009

Hi Richard,

Wow, you are the man. You even know the wires color code for the ITA.

When I received the device from EBAY and I was very confusing so I have to take a photo of my ITA connectors + wires and sent to the seller and asking him which ones I should connect. After 2 days, he sent me the instruction on the wires you just told.

I will do like you said for the FINE tuning this weekend and I will come back here later (may be 2 weeks since my car ECU need to learn for several days before I can see the differences).

I really appreciate your time & your help. Your Web Site is so wonderful – a lot of knowledge on car stuffs.

PostedbyFriendly Guy
June 14, 2009

Hi, gr8 post thanks for posting. Information is useful!

July 6, 2009

Hello! Thanks for the post. It is really amazing! I will definitely share it with my friends.

July 15, 2009

Hi guys, I was also a victim of that named chips.. Of course it does not worked..! 🙂 but..! It took of my check engine light on my 1998 Olds LSS 3.8L! wow hahahahahah 😀 I do not know why/how but it did.. I looked inside and ” hello 4.7K resistor !” 🙂
So.. do you know what are the values for this car ? I just want to test it, and of course I can afford myself THE 10 cent VALUE OF A RESISTOR ! hahahah 🙂


July 15, 2009

Hello Vick.

Thanks for reading. Just spread the word so this stops happening and enriching those scammers.

About the 1998 Oldsmobile LSS, the values are as follows:

Temperature ———– Resistance
212F (100C)………….177 Ohms
194F ( 90C)…………..241 Ohms
158F ( 70C)…………..467 Ohms
122F ( 50C)…………..973 Ohms
104F ( 40C)………….1459 Ohms
86F ( 30C)………….2238 Ohms
68F ( 20C)………….3520 Ohms
50F ( 10C)………….5670 Ohms

As you can see, 4.7K (4700 Ohms) is supposed to be a good value in theory, which is between 68F-50F, but of course it is a complete scam.



August 1, 2009

good READ!!!

August 11, 2009

What would be the optimal IAT resistance values for a 2003 Infiniti G35 Sedan? I have heard of people using resistors with a value as high as 100k ohm. Does it matter if the resistor is 1/4 or 1/2 watt? Thanks!

August 11, 2009

Hello ElectroGeek.

Thanks for your message.

Resistors can be 1/4 watt as the signal passing through it is a 5V signal. So if you are using 4.7K for example, current = E/R = 5/4700 = 1.1mA, then, Power = E x I = 1.1mA x 5 = .0055 watts or 5.5mW. That means that 1/4w (.25w) or even 1/8w (.125w) is way more than enough.

About the values for the 2003 Infiniti G35, we have in record only two values and looking at them, it will be obvious that 100K is way out of range. The values are as follows:

77F (25C) = 2.1K
176F (80C) = .37K (370 Ohms)

So for less temperature than 77F(25C), just raise the resistance value, maybe up to 3.3K, 3.9K or 4.7K which are already available and common resistance values.



August 11, 2009

2002 Toyota Highlander 3.0L 2WD Basic (1M) 1.)IAT is part of MAS so what are the 2 wire colors and resistor value I should use in FL?
Current MPG ave. 22-24. 2.)Have OEM coldbox with K&N…what can I use to increase cold air flow into this OEM box? Thanks much.

August 12, 2009

Hello Stan.

Yes, the IAT is embedded in the MAF sensor on the 2002 Toyota Highlander 3.0L.

It has 5 wires and the IAT is wired between #4 (Red/Yellow) and #5 (White). In this case, #4, which is the IAT itself, must be disconnected from the MAF and connected to one lead of the resistor. The other resistor lead goes to #5, without disconnecting it from the MAF.

About values, they are the following:

-4F (-20C) = 18.4K
68F (20C) = 2.2K
140F (60C) = .667K (667 Ohms)

Thanks for reading,



August 12, 2009

Thanks Richard….wrt throttle body spacers…is there one that fits my 2002 Highlander intake; and, if yes, what is the part number? Thanks much.

August 12, 2009

I am sorry Stan, but I can not advice on that as I don’t have that information.

What I can tell, is that I would save my money instead of buying a throttle body spacer, since the original idea, whichever it was, was meant for carburated and TBI (Throttle-Body-Injection) engines, on which, the spacer was in between the air/fuel mixture and the intake manifold.

On today’s cars (based on your 2002 vehicle), the injection is done in a point farther below the throttle, making the spacer due changes (if any) only on the incoming air instead of on the air/fuel mixture.

Of course, other physics factors not considered at this moment may apply here, so if you end up doing the modification anyway and get any improvement (tested) on saving or performance, it would be very nice if you share it here with us, so we all can benefit from the power of information.



August 12, 2009

Thanks Richard. Final thought in my current quest for mpg…is there instrumentation you can suggest to measure air temp at various points “under the hood” to determine which resistor value would be best to use for average Florida driving?

August 13, 2009

I am sorry, but I don’t know of such an instrument. That was the original purpose of the IAT sensor anyway. Besides, regardless of what you are trying to accomplish, it all will depend about 99% on “how important” is the IAT for the target ecu and that is defined in the programming it contains.


August 13, 2009

Thanks Richard. I am going to try a 5K resistor (1/4 watt) and see how the ECU responds in our 2002 Highlander. Thanks again, and I’ll report any significant results, as my primary motivation is mpg.

August 21, 2009

no comment just question, have an 05 ford f-150 4.6liter bought an intake air temp sensor don’t no where to put the connector. don’t see any hard place to look for good directions or even a picture. please help!!!!!!!!!!

August 22, 2009

Hello Mark.

Did you buy a sensor or a sensor modification (resistor)?

If it is a sensor, I’m not sure what you have, as the IAT sensor is embedded inside the MAF sensor, which is sold as a whole part and is located in the air filter assembly. It has a 6-wire connector.

If it is a modification (resistor), the internal IAT is wired directly to wire #1 (gray) on the MAF sensor. It must be connected from wire #1 to wire #5 (Black/White).



August 22, 2009

I bought a performance mod on ebay and I did not open it but the ohm meter says 32.77K

August 22, 2009

Hello Covert. Very high value indeed for an IAT…

If you find anything (info, internals, performance, etc.) and wish to share it here, it would be very nice from you.

Thanks for the info.


September 9, 2009

Hi! I was surfing and found your blog post… nice! I love your blog. 🙂 Cheers! Sandra. R.

September 22, 2009

I like your thread and find it very interesting. I want to try the IAT mod on my 2007 Honda Accord 2.4L SE. It got IAT/MAF sensor with 5 wires, can you help identify which 2 wires (color/stripes) for IAT? Thanks in advance.

September 22, 2009

Hello Conrad.

In your car the IAT is wired to wire #1 and #2 and its ground is totally independent from the MAF, so you may directly wire the resistor to wires #1 and #2.

A drawing is included below to make it easier.

2007 Honda Accord SE 2.4L MAF / IAT sensor modification

Thanks for reading,


September 24, 2009

I want to try the IAT mod on my 2003 Ford Focus ZTW 2.0L It got IAT/MAF sensor can you help identify which 2 wires (color/stripes) for IAT? thanks

September 24, 2009

Sure David. My pleasure.

In the 2003 Focus 2.0L, for both the SOHC and the DOHC models, the MAF is the same and uses the same colors. It has 6 wires. The colors are:

1- White Violet (IAT-1)
2- Green/Red (MAF)
3- Black/Orange (Ground)
4- Brown/Blue (MAF)
5- White/Blue (MAF)
6- Brown/White (IAT-2)

Just disconnect (cut) wires #1 (White/Violet) and #6 (Brown/White) from the MAF and put the resistor on both wires, on the part that goes to the car computer, not the MAF (just like in the Honda picture above).

Make sure to cover with electrical tape the wires that hang disconnected from the MAF.

Best regards,


September 26, 2009

Hello again Richard. Thanks a lot. I checked the drawing against the physical/actual and find the embossed #1(black/yellow) to #5(green/yellow). All color/stripe represented in the drawing are ok but the #s are reversed (MAF assembly is Hitachi). Will I go fo the colored wires or the #s? Best regards from Conrad

September 26, 2009

Hello Conrad.

Just follow the wire colors. This is the first time it happens, but I believe that numbers might have been accidentally reversed in my database.

If the IAT is connected in the wrong end, you will notice because check engine indicator will be lit and the engine will either not be able to start or will start and run kind of rough.



September 27, 2009

Thanks for the tip on the useless resistors. I have a 1988 Lincoln Towncar with a new crate engine in it and a new transmission. (I like the car). I was thinking of plugging in a Hypertech power programmer to max the performance. Have you observed any results with these?

November 20, 2009

Hi Richard,

I was pondering the idea of purchasing one of these “performance chips” from ebay until i found a negative comment in the feedback section of one of these ebay chip sellers. It said these are fake and are a waste of money do some research on the net before buying, so I googled it and came across this page and I’m glad I did. I currently own a 2000 Cavalier z24 and installed a cone type filter on the end of the inlet tube and removed stock air box. I noticed a major gain in throttle response and power, but after a while check engine light came on. I dont have a code reader so I am assuming it may have something to do with this modification. Im thinking now the air intake is not being drawn from outside but from under the hood which is quite warm causing the IAT sensor to tell the computer to compensate for the warm temp. So i thought mabey purchasing one of the performance chips may help this problem by changing the resistance telling the computer the air is cooler thus eliminating the check engine light. Anyhow I did the experement and placed the IAT into a cup of ice cubes. Before I started the car was completely cool and the outside temp was around 7 degrees C. It read 2ohms. After placing in cup of ice for 2 minutes it climed to 2.5ohms. So I might try using a 2 or 2.5 ohm resistor and see if it helps. Thanks for posting this page I am definatly not spending $30+ on ebay for something i can buy for less than a $1 at an electronics store. I am curious to see if this does anything, as I am not sure if the 2.4l chevy engine relies only on the IAT sensor to adjust the fuel/air and timing curve. Thanks again for the info.

November 20, 2009

Hello Dalen. Thank you for reading the post.

About your case, I am not sure what can be causing the check engine light to fire, but conical high flow filters like K&N are OK to use for better performance. I guess that the best thing to do is to do a vehicle scan so you be able to know what trouble codes are stored in memory, and, if they are related to the air filter in any way.

About your IAT, as you may know, it is separated from the MAF sensor and is located at the Air Cleaner outlet duct assembly.

About the resistance you read while submerged in cold water, maybe you were looking the x1000 scale in the multimeter, as I haven’t seen such a low resistance value for the IAT. Remember, the lower the value, the higher the temperature it represents. So 1 to 1.5 ohms is too low.

You might check again, and compare with the following table, which is the table of values for the IAT on the 2000 Cavalier Z24, 2.4L engine.

Thanks again and best regards,


Temperature F (C) IAT Resistance in Ohms
176F (80C) 315
158F (70C) 435
140F (60C) 580
122F (50C) 810
113F (45C) 940
104F (40C) 1150 (1.15K)
95F (35C) 1360 (1.36K)
86F (30C) 1600 (1.6K)
77F (25C) 2000 (2K)
59F (15C) 3000 (3K)
50F (10C) 3600 (3.6K)
41F (5C) 4600 (4.6K)
32F (0C) 5700 (5.7K)
23F (-5C) 7400 (7.4K)
14F (-10C) 9800 (9.8K)
December 2, 2009

Hey I am pretty car savy and I want to try this out on my hyundai. What is a good place to pick up a 10cent resistor? like does it matter what kind it is? and what is the ideal temp/ohms you would want? Thanks Jon.

December 2, 2009

Hello Jon. Thanks for reading.

About getting the resistor, it is sold on Radio Shack and also on many online stores like,, etc.

About what resistor, it will depend on the car and model, since every temperature sensor (like the IAT, for example) has a different response. What is common in all of them, is that they are negative coefficient sensors. That is, the more of one value, the less the output. On IAT’s, the more the temperature in degrees, the less the resistance in ohms.

Just let us know on what car you want to try it (Model and Year) and I will check if I have the information on my database. If I do, I will post it here.

Best regards,


December 3, 2009

Thanks for the quick reply,

Okay yeah I read a little further into this after I posted yesterday. I have a 2002 Hyundai Elantra GLS currently, but will be upgrading to a 2006 or 2007 Hyundai Tiburon V6 2.7L. I read about a variable resistor from a diagram above, but I am not sure how to install that correctly. Does it only connect to 1 wire from the ECU versus 2 wires if I used just a resistor?

Thanks, Jon

December 15, 2009

i want to ask for hyunday elantra 1995 with 1,6 Engine, what colour for IAT cable sensor ? and how .. Ohm for resistor? kind regards

December 15, 2009

Aura, your question was answered in the topic:

Please refer to the above post for your answer. Thanks,


December 15, 2009

thanks… great forum.. fast solution, will follow again

kind regards….

December 18, 2009


Does any one know the IAT bypass resitor values for a 2007 Mustang 4.0

December 19, 2009

Hello James.

I am afraid that you will need to do the test described here to find out the resistance, since we do not have information on resistance values on most Ford IAT’s. We only have measured voltages in operation charts, depending on temperature.

If any of the readers have the information or have done the test their selves, we will be more than grateful if you post the information here.



December 29, 2009

I Driving a 09 Swift sport JDM 1.6 Manual

What is the best Risistor For My Ride ?

January 16, 2010

Hi admin!

Im don’t know wich cabel im nede conectin my ressistor. Im haved Volvo 740 ’90’ And my MAF is Bosch, And im haved 5 pin on then.
// Robin !

January 27, 2010

hello i have a pontiac grand am gt 2000 What is the best Risistor for my car

February 13, 2010

Hi Richard, I was woundering if there was a way to trick the throttle body sensor to allow more air into the the intake manifold? and if so would a resistor work then?

February 14, 2010

I have a 2000 powerstroke 7.3 disel.While serching the web sites for info on this truck i found what was called a 10k mod…It was just as you say, a bunch of resistors connected in line a certian way.I went to Radio Shack ,got the parts and built me one of these things.Now mine is a disel and instead of hooking it to the IAT sensor, mine hooked at the ICP sensor. It’s supposed to fool the ECM into thinking that it needs more fuel than it does when you stand on it.In my case this devise worked, as my truck would not sqwall the tires at all before i put this thing on.89mph was max speed also… Now when i floor it my tires really smoke as does my exhaust with un-burned fuel.My top speed is around 105 now. MIL will flash on and off when i switch it on and floor it, and the transmission seems to shift harder. Frinds said they heard me sqwall tires as transmission shifted into second.I just know this devise improved my trucks off the line performance.I have to buy two new tires every year from showing off..Is it harmful to my engine? I’m not sure…Waste fuel? Most likley.If you own a Ford Powerstroke and want more take off performance, look up this mod in the disel forums and try it.It worked on mine and only cost me maybe $10.00 in parts at Radio Shack to build.Cheaper than the bully dog’s and banks chips but primitive compared to them also.There’s another mod like this out there that adds even more take off power also. it uses resistors with a different value.I feel that i may have gained maybe 50- 70 hp when this is switched on.Not sure though,just a guess as no dino was used.DD5

Postedbyrandy becraft
February 15, 2010

Hi I have a 1990 Ford Taurus with a 3.8 V6 it also has a cold air intake, I ws wondering what should I hook the resister into, what size of resister do I need and how much horsepower do you think this will increase my car with, thanks

PostedbyAcer Rodgers
February 18, 2010

I installed the resistor module in a 2005 PT Cruiser and I have to tell you it did increase performance noticeably.

You can buy this modules for 25 bucks on Ebay, and while the resistor itself may be only a few cents, it comes with a neat packaging, with a box, clamps and self-adhesive, so installation is literally 5 minutes. I would hardly consider it a ripoff, given the value of $25 vs your time.

February 22, 2010

Well, we don’t call it a rip-off because of the price alone, as if it would work, it would be too cheap to believe. We call rip-off to something that someone ask money for, with the promise of something that never happens.

Anyway, you say that it worked. Did you test it on a dyno?

I can make X-Ray eye glasses for that price and even pack it in a nice box for storage. Will you be mad of me if you buy it and find out that you can not see through clothes, even if I guarantied that with my product you would?

Please remember that our senses response can be modified by our brain under suggestion. I am not saying that this is your case, but if anyone has a REAL scientific / technical prove, we more than welcome him / her here to show everyone the results.

Thanks for your comments and thanks for reading. I really appreciate it.


February 23, 2010

Hi Richard, I didn’t need a dyno to tell the difference. It was quite noticeable in case of the PT Cruiser.

You will have to agree that the IAT trick will work in some cases as it will produce a richer mix, which means more power (as long as it’s not too rich).
I’m not saying that it will work for every car, in any circumstance. Better tuned ECU’s are probably more difficult to trick or may not improve at all because they’re tuned for high-performance already. Anyways, the PT Cruiser 2.4L engine is a pretty lazy one and the resistor did improve power output for me.

I just thought I share my experience with others who are willing to risk $25.

February 23, 2010

Thanks again Mic414.

I appreciate the info and I’m sure that those with the same car will appreciate it too.


March 26, 2010

Hello Richard, I was reading all this and has helped me because it was also about to buy one of these modules. Now if I could help knowing that resistance would put in my car, I have a 1998 Chevrolet Cavalier 2.2L. or show me what is the process of installation of the resistance. thanks

April 15, 2010

Interesting read. Another thing I have been puzzling with is this…

My 02 sensor gives feedback for the burn ratio as well- so although there may be a timing advance (if the sensor is fooled) the extra fuel would not burn, causing the 02 sensor to feed this information back, for the ECU to then respond by reducing the fuel!

I did read that a leaner mix can be more eficient and a slightly** richer mix can give a bit more power, but with the 02 sensor working away, I cant see much advantage from the resistor idea. Also, before adding a ‘fixed’ resistor, this air temp sensor would be giving changes all the time- a fixed resistor will surely be ‘wrong’ most of the time!

PostedbyJon Doe
April 25, 2010

Thank you for the information. It clarifies what I was thinking

PostedbyG. Capano
April 27, 2010

So the IAT sensor is the sensor on the air filter hose going out of the vehicle (right before the air filter) on the BMW 2001 325i?

PostedbyG. Capano
April 27, 2010

On the 2001 BMW 325i, it is located on the intake manifold, located on top-center of the engine. It has 2 wires on it; one is gray and the other is gray with brown.



April 28, 2010

I can not seem to locate iat sensor. Do you have any pictures for the BMW 2001 325i?

PostedbyGino Capano
April 28, 2010

The only image we have is below. It is showing the location on the intake manifold.


2001 BMW 325i IAT Sensor Location
April 28, 2010

That looks like inside the engine?
Is the iat inside the engine?

PostedbyGino Capano
April 28, 2010

No Gino. That is over the engine. You just need to remove the top covers, depicted with the red circle on the picture below.


BMW 325i Engine Bay
April 29, 2010

I have an eagle talon. I know the premise of this whole article other than ITS a SCAM! is that any results depend on whether or not your IAT sensor is important. now if I wanted my car to run lean then I should look for a transistor that is geared for high temps so it will not use as much fuel in the combustion chamber, right? is that how this works or do I have it backwards?

April 30, 2010

Hello Patrick.

Yes, you are right, if the IAT resistor would be that important in your car, then for saving gas you should decrease resistance value in ohms to make the computer think that the temperature of the incoming air is hight.

Best regards,


April 30, 2010

Richard, I have a 2007 cadillac dts I have a resister chip and want to try it the instruction that came with it are not clear could you tell me which wire to use With the plug off and looking into it i have the following wires
1,tan with blue stripe, 2 tan, 3 black with white stripe, 4red with black stripe, 5 yellow

April 30, 2010

Hello Art.

In your car, there is a 5 wire connector in the MAF/IAT sensor assembly. The IAT is wired to wire “D” in the list below, which is color Tangerine. Just wire the modification resistor from there to Ground, which is wire “C” (Black/White).

A – Tangerine/Yellow
B – Pink/Black
C – Black/White (GND)
D – Tangerine (IAT)
E – Tangerine/Dark Blue

Check the picture below for reference.

Best regards,


2007 Cadillac DTS IAT Modification
May 2, 2010

Hi Richard,

curiousity has got the better of me!!

Can you access the resistor values for an Opel Calibra 97 x20xev engine?


May 2, 2010

can u give me with picture MAF wiring diagram for IAT Resistor my vauxhaull zafira 1.8 ? kind regards

May 2, 2010

Hello Matt and Aura. I regret I can not help right now. My database have information mostly on vehicles sold on USA. We have not information on Opel or Vauxhaull models.

I know that Opel for example, can be identical to some GM models, but I have not the information which ones.

If any of you have any information on a GM or any other US market model that is similar to yours, just let me know and I will be glad to let you know about the resistance values, wiring and physical location.

Again, I am sorry I couldn’t help for now.


May 2, 2010

Vauxhaull zafira is same for Chevrolet zafira with GM production.

May 3, 2010

Hi Richard.

I thought that may be the case. Sorry for skipping over the Atlantic and invading your forum!!!

I’m in England, the old one!, and just found your article interesting.

Thanks for consulting your database. Maybe I should try the iced cup test.

Thanks again.


May 3, 2010

Hello Matt and Aura.

Matt, don’t worry about that. You are very welcome here.

Well for you both, Matt and Aura, it will be a good idea to do the “iced cup” test to be more accurate, but if your vehicles have GM equivalents, this might not be right, but I am then posting a general GM IAT temperature vs Resistance range values.

The following are the most common values on GM vehicles and in general more or less with most vehicles. Just a few differs from that.

Wish you both the best and good luck.

GM IAT Resistance Vs Temperature Range Values
May 4, 2010

Hi Folks,

Did my iced ambient thermistor test.

Got a result of about 4100 ohms on a digiohmeter. Now I will buy the most appropriate resitor to see if it has any empirical effect on the performance.

Richard, any tips on attaching to the ecu IAT terminals? I haven’t got a soldering iron at present.

Cheers for help,


PS I will post any results I can deduce 😉

May 4, 2010

Well, I guess that the table above is close to your values then.

For alternative wiring, you may use “wire nuts” of a small enough size and doing a twist on some exposed wire and the resistor leads.

Other very often thing used on automotive wiring are the quick taps. Both are pictured below.

Just make sure that the connections are electrically isolated from ground (no exposed wire) and from any voltage source and also keep it away from heat as possible, as these parts are plastic and can be molten, unprotecting the connection.



Alternative wiring accessories
May 7, 2010

Thanks for the comments Richard.

Many Thanks,

May 9, 2010

hello Im car vw caady 2008 model .Im how todo make mods.

May 9, 2010

Caddycaddy, I am sorry I do not have information on those models.

If any of the reader know the answer and is so kind to share it, you are welcome. We will appreciate it.


May 17, 2010

This is such a great resource that you are providing and you give it away for free. I enjoy seeing websites that understand the value of providing a prime resource for free. I truly loved reading your post. Thanks!

PostedbyAutism Symptoms
May 21, 2010

Hi Richard,
Great information!
What colored wires on the MAF are for the IAT on a 2007 Silverado 6.0L.

May 21, 2010

Hello Ken.

As per our records, for the 2007 Chevrolet Silverado 6.0L, the circuit is the picture below. Note that the IAT is directly wired to wires A (Black) and B (Tangerine). You just cut those two wires and connect the resistor to the end that goes to the ecm computer.



2007 Chevrolet Silverado 6.0L MAF / IAT
May 23, 2010

if you don’t take the iat out of the circuit and just install a resistor inline to make the computer c a higher resistance to think its a lower temp. This way it will work but will always c a lower temp. wouldnt that be better that totally take out of the circuit like you r saying or the chip scammers r doing.

May 23, 2010

Hello Bill.

Thanks for your comments.

If you put the resistor in series with the IAT, then yes, you are right. The resistance that the ecm will see will be always higher than it really is, plus the variation induced by the IAT with temperature oscillation.

So if the IAT range is let’s say 100-5000 Ohms, and you put a 4700 (4.7K) resistor in series, then you will move the range up to 4800-9700 Ohms, which may be out of the circuit’s response range, making it always read a very low temperature.

If on the other hand, you put the resistor in parallel with the IAT, it will be the opposite. The resistance will always be lower than normal, including the variation from the IAT.

It is visually explained below:

IAT mod serial vs parallel comparison
June 18, 2010

Ive got a 99 Dodge Ram with a 318 manual tranny, and cold air intake. What would you reccomend to use as the preformance chip? I was looking at the resistors on ebay as well as a throttle body spacer.


June 23, 2010

I just wanted to say that this site is realy special and I’m happy that i found it

I’ve gotten exposed to quite a lot of info here and just wanted to give my 2 cents. I’m about to write a good article for this forum and I’ll publish it as soon as i complete it.

If anybody need some help about it, please MSG me.

Thank you.

It’s a good thing. 😉


March 4, 2014

I recently bought a resistor type mod touted as a “fuel efficiency” chip and installed it on my 2009 Dodge RAM 1500. The fuel economy has improved, from 15.7 to 16.4 mpg. This is based on 5 tanks of gas with the chip installed. Any comments on “fuel efficiency” chip/resistors versus “performance” chip/resistors?

PostedbyKell Corum
March 29, 2014

hi im looking to fit one of these to a 2000 ford focus 1.4 engine the airflow meter has 6 wires going in to it which ones do i cut? thanks

March 29, 2014

What would be the best resistor and instructions for a 1990 Toyota corolla. The reason for not trying the little box sold on ebay. Is that it never made sense until now. Think you all for this eye opening expirence. It is a wonderful thing you all have done. Thank you very much !!!

Postedbylarry vanhoosier
March 31, 2014

Hello Chris. Is it a diesel engine?

March 31, 2014

Hello Larry. For a 1990 Toyota Corolla the IAT is a stand alone part. It is plugged in the air filter housing and it has 2 wires, one is BROWN and the other is YELLOW with BLACK. You must cut the YELLOW/BLACK wire and put the resistor in series with the wire. You may use a 3.3K resistor (3,300 ohms) or ORANGE-ORANGE-RED-GOLD color code resistor. A 3.3K resistor will simulate an approximately 15 degrees Fahrenheit incoming air temperature. To calculate resistance from color code and instead, you may use our simple calculator below (in mobile browsers, click on “exit mobile edition” so it displays right):



March 31, 2014

its a 1.4 petrol engine, with a six wire connecter to the air flow meter

April 17, 2014

i bought one of those boxes for $13 pp i put it on my 96 siverado pickup. i did see one thing . the rpms at 70 were much lower than thet were before. i put mine in series .
also getting better gas millage due the the engine running less rpms

April 17, 2014

Hello Marv. Thank you for your information. Better mileage is not from lower RPM. If it is real, as it must be measured by anything else than intuition, I guess that it could be because of the engine injecting less fuel. Lower RPM is typically what an ECM does to the engine when temperature is high, which could be what the resistor is making the ECM to “think”. The engine is physical and it is real. Giving it unreal values would not be much useful, at least in the long run.

Again, thank you for sharing your experience. It is much appreciated.

April 22, 2014

I have a 2006 toyota tacoma 4.0l and when i was pulling out the motor i pulled out both the crankshaft sensor and the upstream o2 sensor. I was wondering if you could send me a wiring diagram of both of them?

April 22, 2014

Hello Dylan. Here you will be able to download the diagram of the whole EFI system of the 2006 Toyota Tacoma 4.0L.

Best regards,


April 26, 2014

Very very helpful article keep up the good work! Your a legend

April 29, 2014

hi man,
i have a vw polo 9n3 1.4 16v 59kw petrol, what resistor should i use and where is the IAT placed?

April 30, 2014

I have a ford focus 1.8 tddi (intercooled 90bhp). What ohm resistor would be best for mine.


PostedbyLiam D
May 4, 2014

I have vw golf 4 2,0L petroland gas 115HP year 2000
what resistor should i use and where is the IAT sensor placed?

June 12, 2014

on a older camaro, probably a 98, I was able to increase max horsepower by 5 horses. This was tested on a dyno at wide open throttle. It does work but I wouldnt do it.

June 19, 2014

Thank you for sharing Jeff.

November 22, 2014

Anyone know the values of the air flow meter for a 2006 Honda Accord

December 18, 2014

I have a 2001 Honda Civic. Which resistor should I use and do you have a blue print for installation?

December 19, 2014

Values? If you mean resistor value for the IAT sensor, in Honda cars that use Flow Meter of MAF, it will be around 2.2K (2,200 ohms) to represent a low temperature of about 30 degrees F. Please note that many Honda cars are MAP based instead of MAF based.

December 19, 2014

If you mean resistor value for the IAT sensor, it will be around 2.2K (2,200 ohms) to represent a low temperature of about 30 degrees F.

December 19, 2014

I put the resistor in parallel, you think it is recommended that installation?

December 19, 2014

Since the purpose is to increase resistance, a resistor in parallel will do the opposite, it will decrease resistance, not working for the purpose. Resistance in parallel will be lower than the lowest value of the two parts. It will work increasing resistance by either replacing the IAT by the resistor or putting it in series with the IAT, which would be simpler, as only one wire would need to be cut and then joining the two resulting wire ends to the two ends of the resistor.


January 18, 2015

CIao volevo sapere dove si trova il sensore IAT su peugeot 206 1.6 HDi e quale resistenza bisogna usare e in base alle resistenze di quanti gradi varia la temperatura. Grazie.

May 21, 2015

Hi Richard, I think it an excellent did You are doing for the community or people in need in general, so big Thumbs Up for You My Man!!!!!
I have 1990 Toyota Celica 2.2 that Iam currently fully rebuilding by my self, I I have red your suggestion 4 a guy with same year Camry, so I think same can apply in my case. I have tested the sensor in heat and cold and it varies between .08 and 4.36 on the 20K mode of the Multimeter, so I recon a 4500 or 4700 Resistor will be safishiant Enaf, rite-?? But want to ask why you recommend a serious connection with the wire, to a supposed to a parallel -??. Also 100% agree with you that this mode alon will make minimum or no affect at all, so do You think that doing same to the Coolant temp sensor at the same time will help-???

May 21, 2015

Hello Anatoli. Thanks for commenting.

About the resistor, it should be used in series with any of the two wires that goes to the IAT sensor to increase resistance, or replacing the IAT sensor at all. In parallel, you will decrease resistance, like air going hot.

I have not tried with the coolant sensor. Nor sure about that one. What I have seen is people doing similar modifications to the oxygen sensor to alter the voltage value it sends to the ECM. If I remember right, voltage output of the O2 sensor varies from 0.6V to 5.0V, where the lowest = the more oxygen. Following this norm, using a resistor network, like a voltage divider, may be be used for lowering the output voltage swing, without eliminating the swing. You should also know, that this is only theoretical, as O2 sensor is only used in closed loop mode. Once you accelerate with more than 50% throttle, it will jump to open loop mode, reading then the values from the corresponding fuel table for the needed on-demand injection.

Best regards,


May 22, 2015

OK i think you got some incorrect thinking here. If you cool the sensor down then the resistance is decreased meaning it is sensing cold air ! So the lower resistance you put in the circuit makes it think its sensing cold air . If you heat the sensor (original car part)the resistance is increased ,so putting a high resistance in the circuit will make the car think the air is hot ! You state the OPPOSITE ! Possibly to confuse the correct way to do it ?

Postedbydave gronz
May 22, 2015

Hello Dave. If we are talking about the IAT, which is a thermistor with a negative coefficient, the more the temperature, the less the resistance.

Example, in some of the GM IAT tables:

212F (100C) — 177 Ohms
194F (90C) —- 241 Ohms
158F (70C) —- 467 Ohms
122F (50C) —- 973 Ohms
104F (40C) —- 1459 Ohms
86F (30C) —– 2238 Ohms
68F (20C) —– 3520 Ohms
50F (10C) —– 5670 Ohms

As you can see, the more the resistance, the colder the air. You can do the experiment. Take any IAT, connect an ohmeter to it and spray component cooler spray over it or put some ice around it (without the ice touching the test leads). You will see the resistance increase 🙂

Since increasing the resistance is equivalent to colder air, then the best way to install it is in series with the circuit. Parallel installation will decrease the resistance, equivalent to hotter air.

The idea of putting it in series instead of replacing the IAT completely, besides what is stated above, is because it will be simpler and the circuit will keep the normal voltage variations caused by temperature variations. It will be just like moving the complete range of response to higher values.

I hope this clears the doubt.

Best regards,


July 23, 2015

Did I mess up ecu by taking out the egr crap.the car ran awesome with lots of power then about 8 miles later go’s into limp mode anything I can do

PostedbyRay pearl
August 5, 2015

Hello, great information here! can you please advise on the wiring diagram for a 05 Mazda tribute 2.3L engine. the voltage coming from the iat is over 6vdc I have a p0113 code, by adding a resistor, I think I would be able to lower the voltage and temp value, making the check engine go away! please advise. thanks.

August 6, 2015

I found the diagram on line, the IAT sensor is attached to the MAF sensor. I cut the wires, went to Radio Shack, bought the 1/4W 4.7K resistor, added it to the 5vdc wire and the return wire(6.25Vdc in my case) unplugged the negative of my battery. The check engine light is gone and the car runs much better. 2005 Mazda Tribute 4cyl.

September 15, 2016

What’s the optimum IAT resistance for a 2003 Mitsubishi Colt Rodeo V6?

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