Cold Start + Check Engine Light

[iananderson02]

Hello all,

Have read similar threads but haven't found my answer. Car is a 97 sport, M44. Problem is:

POOR cold starts, very low rough idle. I am able to rev the car and keep the engine going but sometimes it will die anyway. After about 30 seconds the idle is perfect and the car runs great. When the idle is low and rough the CEL will come on (and stay on), pulled the codes: All related to misfiring (random unknown cyl and cyl #4). I cleared the codes and can drive all day long with no issues and no CEL. As soon as the car sits long enough to get cold again the same problem will resurface. Same CEL codes and all.

I have cleaned the ICV, it was dirty, almost completely seized. This smoothed out the idle at all temps (somewhat) but did not fix the problem. The Crankcase vent valve is new and so is the hose from the valve cover to the CVV. The airboot has a few surface cracks, the cracks do not go trough to the inside (I inspected the inside and sprayed carb cleaner on the cracks, has no affect on the idle). I sealed the surface cracks with silicone anyway, just for a temporary aid. I also see a few cracks on the vacuum lines that go to the fuel injectors, also minor but I will be replacing these and the air boot as soon as the dealer gets them in stock for me. I don't feel confident this will fix the problem. Plugs are new, not platinum's, gas tank is 1/2 full (i will drain this down and refill in hopes that this may be caused by bad gas).

I know i've pretty much covered my basic's, What else should i check. Any wild ideas. I'm hoping t get this on the front end before I get stranded. Thanks in advance....

-ian

[HuGo]

Try new plug wires. That might be a problem for the misfiring.

[iananderson02]

If the plug wires were bad wouldn't the car misfire at all temps? The "misfire" is ONLY while VERY cold (its been about 10F when i start the car in the morning the last few days). It goes away completely after about 20-30 seconds of running...

[teetime4one]

my car does the same thing...it hates cold starts.
i'm still trying to kill it tho...so i figure this is a good start.

[AquaCali]

Check the plug wires, cooler temps = condensed moisture as the engine warms up the moisture evaporates no more shorting out of the wires.

[marko]

I think it is the crank position sensor... I had the same problem - changed the CPS, & its all good now.

[iananderson02]

Good suggestion but crank or cam position sensor will almost always throw a check engine light with the relevant code.

The strange thing about this is that the car runs really really well after a VERY short time, about 10-30 seconds. Not long enough to really get any substantial heat into anything. disconnected from the engine (such as plug wires) I don't think it is caused by condensation unless its inside the fuel lines that is...

I'm starting to think its a leaky fuel injector. Perhaps the cold is not the cause, it may just be a long period of non-running (which would allow the car to cool off), leaving time for the leaky fuel injector to drip until the pressure bleeds off. Spark plug gets wet with gas, car becomes flooded in one cyl and thus the rough running. As soon as the plug dries and cleans itself from the internal cyl temp it runs well again. I know that many e36 owners have experienced this after 10 years and 100k+ miles.

[led_zeppelin84]

don't have exactly the same one, but I wanna post here to keep from opeing up a whole new can o'worms...basically when I start my car, the car idles real low, hasn't started dying during wam up....yet....but if I don't give it at least a seven minute warm up, it sputters while I drive. like, when I hit the accelerator it aint getting the gas...also, when I stop at a light the idle drops to almost dead...like its choking to stay alive....but if I give it the 7 minutes, the engine stays on, the idle stays up above 1000 rpm...any thought? oh and for some reason, when I run my a/c the engine struggles and does a deep humming and drops an idle when I'm stopped somewhere. not the whole time, intermittently, I don't know bout cars though, so I REALLY need help

[tiFreak]

check the rubber boot for your intake, they can crack

[led_zeppelin84]

Originally Posted by tiFreak

check the rubber boot for your intake, they can crack

if that was for me tifreak, preciate it, ill definitely check that out!

[applefan]

Hello raising this thread from the dead
What finally fixed rough idle at cold start ? Was it cracked rubber boot?