Idle Issues

[hamann318is]

I've got a '91 318is that's been giving me interesting idle problems.

When I start the car after it has been sitting for a while, the idle is very rough sometimes causing the car to stall. It usually does this for a minute or so, and after the engine has warmed a bit, the idle is fine. Though, if I let the car idle for a minute or so, the Check Engine light will come on, but nothing idle-wise is wrong.

I replaced all the vacuum lines a few years ago, and they all look fine. I had the ICV out today, cleaned it up a bit, and that seemed to help only a small amount.

What else should I be looking for?

Thanks in advance!

[n2motorsports]

mine did the exact same thing on start up and it's a pretty common problem.

if you've already checked the vacuum and icv, i'd suggest pulling off the throttle body and cleaning it througly and change out the spark plugs.

[Vladi]

What code does the Check light say?

[hamann318is]

The check light is throwing a 1271 Ignition Coil #1. The plugs are somewhat new, but I've never replaced the wires. Perhaps that could be the culprit?

I'm not quite sure.

[Vladi]

Hm...the bad idle should have something to do with the ICV. A bad coil should show it's self while driving...
:confused: You've got two options: test with a known good icv and a known good set of coils.
If you don't have where to get them, first of all try and clean the ICV.

[dcbrufan]

Hmm you can try cleaning up the ICV again to see if it helps. If not, clean the throttle body and check for vaccum leak, esp. the line linking from the crank case to the throttle. Also check if the engine oil cap is properly secured.

If nothing helps, try checking your ignition coils and wires. I have experience rough idling due to a faulty ignition cable.

[Jami318is]

I have been dealing with the same thing for at least 6 months now. Mine has gotten to the point where it is running real rich and that has stolen my mileage and power....Nothing seems to fix the situation for long. the only code I get is Speedometer A Signal ! Not what I was looking for!

Now mine wont idle for nothing and then every now and again it will. Right after the check engine light flashed on and off the car idled around 22,000 which was no fun but after sitting for about 15 minutes it was fine until I went to start it the next day!

Uggggg this is driving me crazy! Nothing seems to be the answer.

[oldtimer]

My Idle was doing the same thing but not as bad from what I have read.  Mine started out with isolating idle between the 500 to 1k rpm  cleaned ICV and replaced the TPS.  the isolating idle still exist however after driving a certain distance then come to a stop light it will idle normal seat there until the light turns it would start to idle rough again betwee 500 and 1k and the "check engine" light will eluminate solid then nothing.  the vacuumm theory will produce something more constant than now and then.  anyone experience this type of isolating idle?