The M103 CIS-E performance ECU module thread

[400Eric]

I recently cured a recurrent high idle problem on Benzer 1 by replacing his ECU with the only other one I had quick access to, the one from Benzer 2. But this left B2 without an ECU so, when I had the first opportunity, I nabbed another one for B1 so I could give B2's ECU back. We'll get to that "new" ECU in a second. I actually installed B2's ECU while I was playing with B1 at the dragstrip and found that B1's ECU was a bit quicker! I'm not going to post the numbers because they are skewered by other factors such as me taking weight out of the car and the D/A numbers steadily improving for the rest of the day. Suffice it to say that the fact that my quickest run of the day was with B1's ECU despite being in the worst D/A of the day and with the most weight of the day (I had no wheelspin all day so that is not a factor) is enough proof for me to conclude that B1's original ECU was the quicker of the two ECUs. B1's ECU number is 008 545 16 32 and B2's ECU number is 004 545 38 32. I would have thought that the older, earlier ECU would have had the edge but I'm sure there are other factors at play here. Heck, it could even be the fact that B2 is suffering from some other issues right now and as a result his ECU is adapted to a bunk set of parameters and there wasn't enough time for that ECU to adapt to B1's much better running engine before I ran the 1/4 mile with it. (I guess I should have run that ECU on the street for a week before I tried it at the track.) Still, this got me wanting to try more ECUs which brings us back to the "replacement" ECU. I deliberately picked up the earliest version of a M103 CIS-E ECU I could find reasoning (and hoping) that since the smog standards weren't as stringent in 86 as they were in 88 and 89 , maybe the older ECU might be a little more generous with the fuel when in the "Let's party" mode. So I ended up with an ECU bearing part number 002 545 97 32. I installed it Sunday. This thing rocks! Both part throttle and full throttle response is markedly improved! If I am unable to get a much needed throttle actuator for B3 in time for our next track day, I'll take B1 instead and quantify my findings. If I don't take B1 to the next track day, I'll take him to the one after that to provide the proof of my results.

I'm creating this thread because I want to get others thinking and experimenting and posting their own results. Please, we need to try to provide proof of some sort like dyno numbers or dragstrip timeslips. I just wanted to get the ball rolling so to speak since you all don't need to wait for me. This is too good to wait! Be aware though that there are plenty of other factors here at play when we switch these ECUs and I don't expect or promise that everyone will see a gain in throttle response and/or power. All I'm trying to do is get you all to experiment a little and post your results so we can get an idea of which ECU seems to be the best for the most applications. Then the ECU that performs the best can be the one you run and the other one(s) can become a spare(s). It's always good to have a spare or two!

Other CIS-E guys and gals are encouraged to participate too! (Early M104s, M102s, M116s, M117s, etc.)

Remember, on the M103s (and probably others) 90 and later CIS-Es are different in several ways from the 89 and earlier ones so I don't think switching ECUs between those and the 89 and earlier ones is a good idea. In fact, I think it's a bad idea and, at best, probably won't work and, at worst, might even fry something. Keep the 86-89s in one group and the 90 and later CIS-Es in the other group.
Regards, Eric