'89 E34 535i 5-Speed Idle/Starting Problem

[gcraiga]

I have an '89 535i Manual transmission that has a problem starting and idling once it has been driven and warmed up. More specifically, I will have no problems starting it cold and drivng to work in the morning, but if I use it again within a few hours the problem comes up.

Specifically, it will take longer to start and sometimes won't start until the second try. Once running, it will drive fine, but will almost stall when idling at stoplights within the first 10 minutes or so of starting. Occaisionally it will completely stall when this happens as well.

This problem had been pretty rare, but progressively got worse over the last six months or so until I started throwing money at it. So far I have replaced the following based on what I've read in these forums and my mechanic's advice:

- Idle Control Valve (cleaned and then replaced)
- Oxygen Sensor
- Crank Sensor (mine was original)
- Electronic throttle switches (replaced to solve other problem)

None of these replacements solved the idle problem, but it seemed to be reduced until a few weeks ago when I couldn't even get the car to stay running after a bad start. At that point, the fault sensor showed that it was the MAF and my mechanic convinced me to replace that expensive part as well as the ignition coils.

It ran better for a few days, but it still shows the problem, albeit less often. I did the stomp test and code 1215 came up again for the MAF. I disconnected the battery and the codes were cleared, but I checked it again tonight and the 1215 code came up again.

Any suggestions for where to look next? Could something be happening when the car is taking longer to start that is effecting the idle?

Thanks in advance.

[bill g]

If it is still throwing a code for faulty air flow sensor (AFM) after replacing it with a known good one then I would be checking the wiring and plug etc to it (or have you done that?). When the ECU throws that code it is really saying there is a fault with the airflow meter OR its connections.
Check for loose, dirty or poor connections, broken wires, or wires shorting against each other.

Bill G

[CarloE34]

Try clean the connection on A and check the air flow on B

[califblue]

check the coil. I'll bet its fried ( happend to me)...look at the distributor cap and rotor