Installing a Chip on the 1993-1995 BMW 325i/525i

February 1, 2010 zilog357 Off All, Automotive, Electronics

This document covers installing a performance chip on a 1993-1995 BMW 325i or 525i ECU (Motronic DME).

E36 Model

First, locate the DME and remove it from the car. The DME is located under the hood, in the engine compartment, below the right wiper assembly (passenger side).

Refer to the drawing above. At the upper right corner of the vehicle (passenger side), which is the upper left corner if you are looking from the front of the vehicle and facing towards the windshield, you will see a soft foam cover. Remove the three black plastic buttons on top, pry out the plastic tab centers to remove the buttons, then remove the insulated foam cover.

Now, you will see a hard plastic cover. Remove this cover by removing the four top screws.

You will find the DME box attached to a wire harness. Remove it by pulling it out. The DME will just slide out.

Do not disconnect the harness until you have completely removed the DME. To disconnect the harness, just pull out the lock lever in the direction shown by the red arrow in the picture above.

Interested in the wiring diagram of the ECU connections of the 1994-1995 BMW 325i 2.5L?

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E34 Model

If your BMW is the E34 chassis model, the DME is located under a plastic cover, as shown by the red arrow in the picture above.

Chip Installation

With the DME on a bench, six tabs hold it at the bottom. Using a small flat screwdriver, CAREFULLY bend the tabs away to remove the cover. Take extra care here, as the tabs are aluminum, brittle, and fracture easily. Do the same when you finish and put it back together, and fold it back into place.

Inside the DME, a white plastic cover sits on top of the EPROM chip. It looks like an “H” (picture below). The chip underneath that plastic cover is the one to replace, so unsnap the plastic cover and, BEFORE removing the chip, note the alignment of pin #1 so you can insert the new chip the same way (see a note about this at the end of this article).

Remove the chip with a flat screwdriver by sliding it carefully under the chip and slowly prying it out of place, little by little, from both sides, one at a time. If you have a simple chip-pulling tool, you may use it instead. When prying the chip upwards, be careful not to break the plastic socket where the chip is inserted.

Now install the performance chip by inserting it into the socket. To do this, align pin #1 with the same corner as the old chip’s pin #1, then carefully align all the pins with the holes and push it down firmly, or gently tap it repeatedly. Reinsert the plastic “H” shaped plastic cover. Now you are ready to put back the DME cover, reinstall the DME in your car, and enjoy the new performance.

The Right Orientation of The Chip

Need a great chip for your 1994-1995 BMW 325i? The chip in the link below is for the Bosch 0 261 200 413 DME (ECM). Its performance compares with top-selling chips on the market from big names.