Rough cold starts and low-dipping idle problem

[streetwaves]

Hey guys. I've had my 318iS for several months now but for a couple I've had some annoying issues. The first is that when the car is cold and I first start it up, I usually get a rough start and it'll fall down below normal idle and feel like it's going to stall. Gets better if I give it gas for a moment, but it seems to be happening more often now and maybe a little bit rougher.

The other thing is sporadic, but often. When I put the clutch in and let the revs fall down to idle, a lot of the time it will dip too low and rumble a little bit and then come back up to normal idle level.

A little background: the car runs great. I recently had the car in the shop because the car stumbled and died one morning and the mechanic told me my timing chain jumped time but bent no valves. He checked the compression which was 175 across all four cylinders and the car doesn't seem to run any differently and the idle seems no rougher, but these problems are still in place. Any ideas? I've mentioned both to the mechanic several times but have never gotten them fixed. At first he said it was the fact that my throttle cable was going bad so he replaced that (it really was failing but it didn't fix the idling problems), then he adjusted the idle and stuff but it's gotten no better. When I mentioned the rough start he said it was probably just the fuel injectors and he put some Lubro Moly stuff in my tank but it doesn't seem to have helped.

Thanks!

[///M42 sport]

I had similar prob. found out by process of elimination. but check TPS sensor, spark plugs, wires, temp sensor, ignition coil, fuel filter, vacuum leak. I would go from easiest, least expensive to most. Or do it the smart way and check the voltage to your fuel/air delivery system.

Mine turned out to be one of the ignition coils went bad, but I didn't find out until halfway through my trail and error way of fixing thing.

[///M42 sport]

oh yeah, if you need a spare ICV I have one for sale. $25+ shipping. I ended replacing mine with a new unit. The old one works fine.

[streetwaves]

oh yeah, if you need a spare ICV I have one for sale. $25+ shipping. I ended replacing mine with a new unit. The old one works fine.

Thanks for the reply and the offer. I might take you up on that depending what I find out.

[streetwaves]

Hey guys, here's an update. I had it in to a shop that I used to bring my E34 to and they said they found a few leaking hoses connected to the ICV as well as one of the cylinders not getting enough spark when cold. So they replaced the hoses and the ignition wires/coils etc. and gave me the car back. For a couple days it seemed totally fixed other than when I'd start it up totally cold it would dip down below idle a little bit until I gave it some gas. But the extremely rough start problem was gone as well as the dipping idle when the car was warmed up.

But the car sat since yesterday and tonight I started it up for a quick ride and my rough start problem was back. That and yesterday when I drove it I noticed some of the same low-dipping idle when driving even when warm. Any ideas? I'll give it back to the shop to see if they'll fix it without charging me more since they assured me they found the problem.

[rafiki]

seems like a lot of m42's all of a sudden are doing this. haha, or a lot of people are posting about it. mine does the same. as stated above. its one of those issues

[streetwaves]

Well I dropped it back with them this morning and from the start they seemed to be preparing an excuse, saying it could be the lifters or carbon buildup and the only way to fix that would be to do a valve job. Sound like BS? Of course they didn't warn me of that before they acted sure it was the ignition problem. I obviously wouldn't do a valve job just to fix a rough start/weird idle. They'll keep it tonight and hopefully find something tomorrow.