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kkos951@968Turbo.de fragen.

This page outlines the procedures for replacing the computer chip on an S2 with a "performance" chip.

At the recommendation of several fellow S2 owners, I decided to order the chip .

The chip has been described as being a Welmeister clone.
(I suppose that means that it performs like the Welmeister chip.)
This is what I have been told  about the chip:

  • it adds roughly 15 horsepower
  • overall, the timing is advanced a little, with a little more advance above 4500 rpm
  • the mixture is richened a little bit
  • the rev limiter is raised to 7000 rpm, which is supposedly still safe for an S2
  • overall driveability is improved i.e. it feels much better at all speeds and rpms
Disclaimer: These instructions and pictures are intended as a guide, to help fellow S2 owners with assistance in installing a performance chip in their vehicle. Read these instructions carefully, look at the pictures closely, and TAKE YOUR TIME!! It took me roughly an hour and a half to finish the job, with my being very careful and not hurrying. If you are not comfortable with doing this type of work on your vehicle, DON'T DO IT!! Take it to someone you trust instead, or just don't do the upgrade!! I assume no responsibility if YOU screw up your car!! I hate to state it this way, but the lawyers in this country have made just about everyone paranoid about liability!!

Note: Electronics such as this are components that are very sensitive to static electricity. Be conscious of this as you perform this process. Some recommendations I had received were:

  • disconnect the negative battery terminal (I did not do so, but the choice is up to you!!)
  • wear a grounding strap
  • ensure that you ground yourself before opening and working with the inside of the "brain"
At the end of this page, I've included the detailed instructions that these fine gentleman had provided. They are what I used when I installed the chip. Print them out, along with this page (with pictures), and use both to ensure that the installation process goes smoothly and quickly!! Good luck and have fun!!

The "brain" of the S2 is underneath the passenger side carpet.
Pull back the carpet, and you'll find a wooden panel. There are four screws holding it in place. Remove them.

carpetpullbacktext.jpg (135K)

This picture shows what you see next. Remove all of the screws as noted in the picture.
I found it easier to remove all of the screws, to make the frame loose enough to get the "brain" out.
I did not remove the black frame, I just loosened it.

brainincartext.jpg (145K)

Flip up the silver connector on the top of the "brain".
This disconnects the wiring harness from the brain.

connectorofftext.jpg (124K)

Here is the "brain" removed from the car.
Pry up on all of the small tabs around the edge.
I used a small eyeglass-type screwdriver to get underneath them enough to get a bigger screwdriver underneath.
Then remove the four screws holding the cover on.

brain.jpg (69K)

Here is the "brain" with the cover removed.
You'll see that there are two circuit boards that must be separated.
Carefully pull up on the back end to separate that end of the two boards.

coveroff.jpg (69K)

At the front end, pry up gently and remove the plastic connector holding the top board to the bottom board.
Note how it was installed, for reassembly purposes.

gutstext.jpg (83K)

Here is the "connector" end of the "brain".
Stick two small screwdrivers, or paper clips or something similar into the two ends, to help unclip the top board.
And then stick another screwdriver or such into the middle, prying gently to also separate the top board from the connector end.
While doing all that, pull back gently on the top board.
This may sound confusing, but once you take a closer look at it, you'll understand.
(Yes, you could really use three hands for this... but it is possible for us humans with only two!! Just be careful and take your time!!)

frontofbraintext.jpg (67K)

Here is the "brain" fully exposed!!
The chip is underneath the plastic H-clip.
Gently pry up on the H-clip to expose the chip.
Once exposed, gently pry up on the chip. Be careful to only pry up on the chip itself, not the circuitry that it is plugged into!!
Given that the new chip's "legs" may not be perfectly lined up, you may need to bend them slightly. If so, at a 90 degree angle to a hard surface, gently bend them in slightly.
Install the new chip, ensuring that it is pushed all the way down and that it is secure.
And then, don't forget (like I did!!) to re-install the H-clip over the new chip.

openboardtext.jpg (143K)

To put it all back together, reverse the order of these procedures.

After putting everything back together, start the car, and take it for a test drive!!
As everyone else who has installed one of these chips can also attest, be prepared to notice a difference immediately!!
The performance gain is subtle, but noticeable. It is well worth the small amount of money

Here are the procedures summarized by Michael Stephenson as posted on the Rennlist S2 mailing list as well as the Rennlist S2 forum.
Be sure to read the additional method below from Tom Boerger for separating the boards; it is much easier and highly recommended to avoid potential damage. 
  • Disconnect the battery.
  • Remove the DME from the car.
  • Remove the cover. This was a little tricky, it took a very small screwdriver to get the tabs pried up enough to use a big screwdriver. The motion is to get the screwdriver blade under the tab and then twist. The motion will raise the tab.
  • Separate the two boards at the rear. I placed my fingers between the boards either end and twisted. It takes a bit of force.
  • Remove the plastic clip that runs under the many silver tabs on the top of the top board. Note the way this plastic clip is installed for when you reinstall.
  • Place two very small screwdrivers, thumbtacks, unfolded paper clips, or whatever between the tabs at either end of the top row of wiring harness connectors.



    (Note: See Tom's procedure below for this next step instead.)

  • Raise the rear of the top board high and pull back. I did this with one hand while pulling in on the two screwdrivers with the other hand. I held the unit against my body for stability. Make sure that if you drop the unit it does not have far to fall. It took several tries and a bit of patience, the secret is to get the rear of the board as high as you can.

  • Once the boards are separated, remove the "H" holder over the chip. I inserted a small screwdriver blade into one end of the clip (there are two small slits on both ends of the "H" - four total) and turned the screwdriver so that it kicks out the bottom of the clip. Do this to both sides. There is an arrow pointing to one side so I did that side first, not real sure if it matters.
  • Look at the existing chip and note the little notch on one end of the chip. Do not forget this orientation. Other than this notch, I did not see a way to make sure the chip is installed in the proper orientation.
  • Carefully remove the existing chip by prying on both sides. I pried mine from one side only and I bent a few of the pins.
  • Install the new chip. Carefully align the pins with the holes. Once they are all started, press down firmly but gently on both ends several times.
  • Once the chip is fully seated, reassemble everything. Reassembly is the reverse of disassembly. I used a small plastic hammer to bend the tabs on the case back to semblance of thier original position.
This is the additional information from Tom about separating the top board at the connector end.

"I was able to get the top board flipped over after some more effort. The thing I was missing was the small "lip" at the front of the top board that hooks around the front of the attachment point. You were able to get around this by raising the back of the top board..... thus lowering the lip enough to clear.... the other way to do it is to use a third screwdriver.... two for the clips on the side of the front mounting point, and one at the top prying down to bend the "lip" so it will clear. Using the 3 screwdriver method, the board pulled straight out no problem". 

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