Rough Idle on cold start

Every morning when I start my car, (first of all, it takes a bunch of turning over to get it to start up) it idles rather unevenly. Then, when I go to back out of the driveway, it's like the gas pedal is posessed - it takes more pedal travel to get the revs up to a level where I won't stall. This ONLY happens on cold starts - every other time it starts up on the first turnover and the engine is normal.

Is this normal behavior for a 98 M3?

Thanks.

Couple of things:

clean your ICV and TB.

Second, there is a software flash for your DME that the dealer should have. I would go to them and request it.

You might want to check your O2 sensor as well, has your gas mileage decreased? You probably are running incredibly rich in the mornings, so it could foul the sensor over the long-term...

Originally posted by jderry

Second, there is a software flash for your DME that the dealer should have. I would go to them and request it.

I had the same problem and I went and requested the latest version of the software and it fixed it.

It looks like you're running through the list of minor problems I've had. Do you want me to spoil the surprise and tell you what you can look forward to? There's only a couple more.

Originally posted by TD
I had the same problem and I went and requested the latest version of the software and it fixed it.

It looks like you're running through the list of minor problems I've had. Do you want me to spoil the surprise and tell you what you can look forward to? There's only a couple more.

That would be great, as I only have a few months of CPO warranty left.

Originally posted by zcasavant
That would be great, as I only have a few months of CPO warranty left.

I had to pay (1 hour labor) for the ECU reprogram. It wasn't covered by CPO.

Under warranty, I had the cam position sensor replaced, the ignition cylinder replaced, and the (under pedal) brake light sensor replaced.

It's also likely that your rear shock mounts are shot and your front control arm bushings are shot. But those are wear items and are not covered.

Originally posted by TD
I had to pay (1 hour labor) for the ECU reprogram. It wasn't covered by CPO.

Under warranty, I had the cam position sensor replaced, the ignition cylinder replaced, and the (under pedal) brake light sensor replaced.

It's also likely that your rear shock mounts are shot and your front control arm bushings are shot. But those are wear items and are not covered.

I was planning on doing the rear shock mounts when it went in for the clutch...but now I suppose that is in doubt as they were "unable to reproduce" the shifting problem yesterday morning. The stinking car was on its best behavior

Originally posted by zcasavant
I was planning on doing the rear shock mounts when it went in for the clutch...but now I suppose that is in doubt as they were "unable to reproduce" the shifting problem yesterday morning. The stinking car was on its best behavior

What amazes me is that they had me drive with a tech in the car so that I could reproduce it for them. However, damn it, my car was on it's best behavior too and I could not even replicate it for them but they still replaced the tranny under warranty.

I have a rough idle at cold starts, but I doubt it's the same thing. It goes away as soon as a fan shuts down - perhaps the exhaust/fresh air mix fan?

When do the control arm bushings usually go? This isn't on my list of things to watch for.

I did have the water pump replaced yesterday at about 40k - right on schedule. They installed a refurbished unit, so it's sure to be the ss impeller again. On the other hand, that part is now covered for life by the dealer and labor is covered for two years. I don't understand why when they replaced it under warranty, but who's complaining? My shocks, contrary to conventional wisdom, seem just fine at 40k (now watch them start leaking on the way home).

Unfortunately the warranty didn't cover the belts that had to be replaced.

You may also consider getting the shark injector for $350. It'll be another ~250 more, but you do get the typical SI benefits. BTW, the SI is supposed to fix this cold rough idle too.

Originally posted by TD
I had to pay (1 hour labor) for the ECU reprogram. It wasn't covered by CPO.