RomRaider

Here's another 2k rpm cold start issue. You blip the throttle, and the idle goes back to normal. Hoping to get some guidance on what's causing it. I have SAI and post cat o2 removed. I have disabled Catalyst heating tables, and disabled the catalyst overheating protection fuel enrichment table. Seems like others have ran into this issue without much luck in fixing it as well. I took logs of it working and when the cold start issue occurs. Based on the logs, the IACV is doing something weird. In the bad log, you can see the IACV doing something odd, then it works correctly once I blip the throttle. This is MS41.2.

Let me know if you need anymore info.

Thanks!

I'm also having this problem with MS41.2 and MS41.3. It's not consistent, not sure is it's mechanical or setting related.

I also had this problem after my first remap to turn off the EWS and advance the ignition timing by 1 degree.
I thought I had s*** everything up.
But with my car, the problem of accelerating after starting only occurred after using the car normally and leaving it stop for about 4 hours.
After racking my brains disassembling and assembling sensors, changing CH, COP, idle speed and warmup parameters, I decided to download the original map and compare it with what was in my car, to my surprise the knock and ignition timing maps were all changed with totally crazy and absurd parameters.
I don't even know how the car was running.
I believe a previous owner had problems with the knock sensor or the idle valve and tried to bypass the sensors.
After loading the original map and making my changes, the car is perfect.
No more crazy accelerations.
Sorry for my English.

I have had this problem before on my M52 swapped E36 318, in 2 different flavors!

1. Immediately after the swap, the car would frequently idle quite high, regardless of engine temp. Sometimes it would start perfect, other times it would climb up to 4k rpm and stay there. Sometimes the idle jumped around from 1000 to 3000 and back. It was all over the place.
- The problem was a bad TPS sensor. When my foot was off the throttle, the TPS reading would bounce anywhere from 0% (too low, off throttle is 9% for me) to 100%. TPS sensors in these cars are known weak points, so take a look at the readings (or buy a new one to test it). I bought a cheapo one from Amazon and I've been very happy with it.

2. More recently, my car has started to have a brief period of high idle on cold starts only (2k-3k for 1 second, then settle to 1500RPM).
- I was using the throttle cable from the 4 cyl, which is a little longer than the 6 cyl cable. This meant that I had to snake my throttle cable in a couple of unfavorable angles before reaching the throttle body. I believe that after the car had been parked for some time, the cable would "settle" into a position which cracked the throttle body open slightly, causing the high idle. I was able to fix this by stomping on the throttle 5-10 times before starting the car to get the throttle cable unstuck and close the throttle body. I diagnosed this problem again by looking at the TPS readings on a bad cold start, and a good warm start. On cold starts, my TPS started out around 13%-18%, and only would return to appropriate off throttle values (9% for me) after a brief drive where I actuate the throttle a few times. The permanent solution was to just swap the throttle cable for a 6 cyl one, and adjust the pre-tension so that when I'm off throttle, the throttle body slams shut.

Moral of the story is check those TPS sensors! They like to cause driveability issues.

Oh, and also check your ICV and hoses for vaccuum leaks, the usual suspects for idle problems. Good luck! Keep us updated if you figure it out.

Just another story about fixing a high idle that might help. Im running a m52b28 with a ms41 in a e30 with a m50 intake, m50 throttle body/tps, and s50 cams.

My idle was all over the place and was constantly fluctuating and would sometimes stall, my fix was to adjust the IACV ECT table at 60 and 90 down to 20% and then the target speed to 850 and it completely solved it. Seems like the PID was getting all wound way up trying to reach the target idle because of the camshaft swap

There's a idle air control table IACV-ECT. When overrpm occurs its because that table value is too high and engine goes to rpm where idle regulation doesn't work. Put lower values to ect temperatures where over rpms occur.

I had similar problem, but on ms41: The cold start ALWAYS was between 2000-2500 rpms instead of 1000-13-4-500. After researching I've found that the ECU was from car with automatic transmission and it needs to be re-flashed by specific way, because the module was not accessible with the ms4x flasher.
What I learned is that there is a part of the memory in the ECU which is only accessible with EDIABAS/ISTA/WinKFP/sx (I'm not 100% sure which one) and you need specific "daten" files to use. In case someone needs them I can send to him.
It's not straight forward about your problem, but I think someone can have a similar to mine problem.

There are different IACV-ECT tables for compensating auto gearbox drag on drive. If ECM configured to auto trans is used on manual car it won't have gear neutral signal and will use those higher IACV values which cause cold start rpm to rise over idle regulation control. But that particular problem can be tuned away by lowering values on that table.