idle problems/trans program

[bad2buck]

Well I am back again I have a 92 Bmw 525I, M50 engine. just started happening and I am in total loss of the proplem. the car runs great for about the first 10 miles than all the sudden the rmp starts acting up going anywhere from 800-2000 rpm back and forth while stopped (sometimes it will die but starts right back up) than after about 10min of that the transprogram comes on. If I am driving down the road at driving speed 40-55 it does the same thing but you can feel it in the engine rpm but not really see the rpm go up just down. any ideas

[whiskychaser]

I dont think its in Bentleys but IIRC there is a signal from the idle control valve to the tranny EGS. So if the ICV is playing up you may get the transprog message too. I will bet you have a code in the engine ECU and the EGS. I'd address the engine one first

[genphreak]

Tranny fluid temp sensor, Connect to a modic to find out as it can read this and the ECU codes and sensor readings. Taking it to a friendly dealer for diagnosis is one way (my dealer knew what they were doing with e34s once, (probably not now) so I could take it to them for an hour of diagnosis (no fixing the problem ) and that used to work out whjen I was stumped. Most shops have a Modic or better, some know how to use them on an e34, but only a few. This diagnosis can be very helpful and I suspect u'll mess around a lot otherwise.

Since your trany may be bad, don't mess around. You should take it to a shop that really knows e34s before the tranny gives out and you have to tow it or do more than replace just the temp sensors inside it.

(This is my experience with the 5HP18EH tranny, not the GM one- I've NFI about that thing)

When just idle is a problem it is a vacuum leak - very common on M50. Once the engine warms it starts using the readings from the 02 sensor, which sees the exahust gases running lean for the amount of fuel going in. ECU gets confused as it is not programmed to understand- nor can it measure air leaks. It hunts around with fuel and perhaps advance, trying to get the engine to combust fuel more efficiently. It does not and the ECU remains confused so engine won't idle smoothly or drive very well.