325i poor idle condition

[325ise30]

OK so ive been experiencing a poor idle condition, witch is at its worst on cold startup, the engine surges, sometimes stalls and idles low at 500-600 rpm. This has been happening for almost the whole time ive had the car about 2 years.
So I have tested (and, or) replaced the following items.
Mass airflow meter
Tested every know electrical connection
New plug wires
Idle speed motor
Throttle position switch
Coolant temp
Checked fuel presser
Cleaned and tested injectors
Crank sensor
Swapped ECM’s and chip
Tested for vac leaks
Also over the summer I rebuilt the top end, just because I felt like it not to solve the problem. So an extra interesting detail is if I reset the ECM buy disconnecting the battery or the connector for about 20 minuets, the car starts cold idles exactly as it should for about 3-5 start cycles, than reverts back. There is an item ive recently been suspecting as the culprit but am not mentioning it so I can get unbiased answers. I know some of you have extensive experience with 1.1 motronic so any assistance would be appreciated. End of rant.

[325ise30]

Come on no replies, I thought some of you guys have Doctorial e30 degrees. And if it’s going to help I am thinking it’s the ignition pulse sensor on the #6 plug wire that’s at fault causing the injector pulse to become “out of sink”. Any opinions would be helpful as I don’t feel like spending money on something that won’t solve the problem, again. :)

[nando]

AFAIK the ignition pulse sensor on the plug wire is only for the tachometer reading, and the pulse sensor on the front of the crank is where the ECU gets the information for fuel and spark.

[sidewaysdave]

have you tried to clean the idle control valve? or is that what you are talking about when you say Idle speed motor?

[325ise30]

have you tried to clean the idle control valve? or is that what you are talking about when you say Idle speed motor?

Yup, even swaped it out for another one.

Nando, believe it or not you can disconnect the pulse sensor and the tach will remain working. Yeah and from what ive read its very similar to cam sensor as it is used for timing the injectors and the car will remain running without it (but in a limp mode state). Ive herd the subject discussed a few times but never in great detail.

Thanks for the replys so far, keep them coming.

[325ise30]

Bump