Installed a performance chip in a Honda P28 and it is not working? Having problems?

Don’t worry. It is more common than you think, as many people choose to install it their selves, even if they have no experience with electronic parts soldering / desoldering and these ecms, even though small and somewhat basic, still are computers with sophisticated and sensitive circuits which are physically fragile. Once in a while, even professionals face some problems, so here are some basic methods to troubleshoot your installation.

This will cover not only the P28, but the P05, P06, USDM P30, P72, P74, P75 and OBD-I PR4 computers as well.

First things first

The most common problem is that the engine won’t rev more than 4000 RPMs after the installation of the chip and check engine light will be turned steadily on also. This will be accompanied by a too rich mixture smell. Some others, show a different behavior like VTEC not activating (on VTEC engines), rough idle and difficulties starting the engine.

Before doing anything, please check that both chips, the EPROM and the latch (74HC373), were inserted in the right direction. If any of those is backwards, correct it and do a test. Note: It is possible that the inverted chip or chips got damaged, needing replacement.

If chips were inserted the right way, the next move is to check if the ecu is still working when put back to stock mode. To do this test, just remove (unsolder) or cut “J1″, which is the jumper that is instructed to solder in when installing a performance chip, and do a test starting the engine. Note: Removal of any other of the installed parts is NOT necessary for this test. This test will rule out the possibility that the ecu got damaged somehow, when the installation was performed.

“J1″ jumper tells the ecu circuit whether to use the internal (stock) program or use the code existing in the installed chip (external program). The ecu will be in stock mode when “J1″ jumper is cut (opened). In that mode it will be using the internal program, which is embedded in the microcontroller itself (OKI 66207). On the other hand, when this jumper is connected (closed), it will force the ecu to use the external program, which is written in the installed chip. So, if when opening J1, everything goes back to normal and problems no longer show, then the problem will be one or a combination of the following 3 causes;

1. The installation wasn’t done right
2. The chip installed is not compatible with the ecu (wrong program)
3. The chip is damaged

If the problem persists after doing the “J1″ jumper test, then somehow, the ecu circuitry got damaged during the installation. For possible causes, keep reading.

How to check the installation

Accidental jumpers or short circuits

The first thing to check is the soldering. You should check for accidental bridges, jumping contiguous pins or connections of the installed parts. Do this firstly by inspecting it visually using a magnifier glass. If nothing is found, then you should use an ohmmeter to check for continuity between every pair of contiguous pins. This is important as the circuit board is a multi-layered one, meaning that it has connections above, below and in between its layers, making some connections not visible. When too much solder is used, it tends to absorb it through the integrated tubular connections that join all the layers and possibly accumulating in excess, jumping two or more points. So, if any two contiguous pins of any of the installed parts shows a resistance reading of less than 1 or 2 ohms, then somehow those two connections got jumped by excess soldering or metal debris.

Broken Connections

The other thing to check is possible broken connections that often happen on these jobs due to overheating when soldering. This computer circuit boards are VERY sensitive to excess heat and this accounts for the majority of the problems that show after an installation.

If a connection was broken during installation, it will be between the chip, the latch (small 74HC373 chip) and the MCU (64-Pin microcontroller unit), because that is the area involved on the job.

Below is a chart that will help you corroborate all involved connections. All the connection should measure continuity (less than 1 ohm) with an ohmmeter or continuity checker. Any reading over 1 ohm is indicative of a faulty connection. If any of the connections displayed in the table fails the continuity test, it must be corrected before going further with the test. Do so by checking the circuit to see if the connecting trace is visibly broken so it can be fixed by soldering. Otherwise, just run a thin insulated wire, soldering between both points that failed. The wire should be kept as short and close to the board as possible. This Will prevent it from picking or generating electronic noise.

Before the chart, there are two pictures. One identifying the involved components and the other, showing a guide for identifying the pin numbering on every respective chip.

Involved components location:

Pin Identification of involved chips:

Connection test chart:

Pin#11 of the HC373, connects to Pin#22 of the MCU

When “J1″ Test Fails and all connections are good

If “J1″ test fails and all connections on the table test OK, we have seen that sometimes the latch chip (74HC373) goes bad by overheating when soldering it or by static electricity. Also, as mentioned before, backwards insertion of any of the chips can damage either one or both, but being this one the more susceptible to such problem.

The less possible but has happened before, is the MCU going bad for the same reasons.

The procedure then, is to replace the 74HC373 first as it is quite inexpensive (about $2.00) and do a test. If problems persist, then it is best to replace the ecu, as a spare MCU is hardly found, adding to this that it is a discontinued product. Also, replacing it will take a greater effort than the the whole installation job and might really ruin the ecu, loosing the money spent in that part anyway.

FAQ

Q – Will a chip with an incompatible program damage my ecu?

A – No. The ecu will activate the check engine light steadily and go to protection (limp home) mode to avoid engine damage. To achieve the purpose of protection, it won’t allow the engine to rev more than 4000 RPMs and fuel mixture will go very rich to avoid destructive lean conditions.

Q – I have had many problems buying chips like these on eBay and other places. Do you know where to buy a real good chip?

A – Yes. We know about problems with eBay. Most chip sellers don’t know about mechanics or racing, neither programming. The ones that sell a chip that doesn’t fail, are selling just the same copies of the same chip. Nothing new and those chips are only fairly good. We highly recommend the chips found on the link below. They are tested and will make your car pull real hard:

http://www.OtherDeal.com

In that web site, you will also find the service of chipping your ecu very affordably, in case you don’t want to, don’t have either the tools or experience, or didn’t find anyone to do it for you.

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