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My '81 528 was tuned up about 8 months ago and runs great, but just the other morning when starting the car cold it would not idle on its own. So I had to manually stay on the throttle for a few minutes until it would warm up a bit and idle on its own. Since then the 'choke' function continues to be missing in action though the car is running well.

Most of my fiddling with cars has been with carburetors so I am at a bit of a loss where to look to fix this. Any and all input would be appreciated.

Thanks,

Crit

My guess would be the Aux air valve mounted on top of the valve cover is stuck either open or closed. They can also be adjusted somewhat too. It provides the function of a fast idle cam on a carb, it lets extra air into the system when it's cold, closing when it warms up. There is an electrical connector on it, but it will function just from engine heat even without it, just somewhat slower. The coolant temp sensor (the one with a plug for the FI, not the one with a single push on terminal for the gauge) is also a possibility.

Hey Crit, I am working on exactly this problem too. I still don't have it licked (I think I messed up a wiring repair), but one thing you should also check after the AAV and the CTS is the quality of the ground connection at the rear of the intake. There's a ring connection from the wiring harness to the engine ground at that point that is essential to the correct operation of the ECU and in particular the warm up phase.

On my '79 it looks like this (point A):

and the configuration is just a smidge different on '80 and later models.

On this subject I am a follower of the gospel of Lenny D. See his posts here and here for more details. Also, I found this PDF on the L-Jetronic system very helpful in comprehending just what the hey is going on in there, and what the AAV and CTS do.

Gentlemen,

Thanks for the pointers. I'll start investigating.

Crit