rough idol when started cold
 

Ok now a post for my M3 ha ha, 97 M3 and its got a rough start in the morning when its stone cold.

it hasnt thrown a check engine light yet ( knock on wood ) and im not going to let it before tomorrow because i need to get it inspected, but what could be the problem here????

what i do now is start it and give it 1500 rpm s for about 45 sec and that warms her up just fine,, after that no problmes.

i would say a choke mechanism of some sort isnt working but im kinda shooting in the dark here

let me know what you guys think:)

It is common but the severity varies a lot by car though. Mine does the same thing.

You could try cleaning the ICV.

ok ill try that -- what should i clean it with and i guess thats a good thing if it s a comon problem -- not like its a huge deal,, just kinda a pain in the rear sometimes

I would start with carburetor cleaner.

My 98 328i is doing that same thing. I cleaned idle control valve and it seemed to help but it keeps doing it.

Then it threw a code. I am at a loss on these codes. Does anyone know what this could mean?


http://forums.pelicanparts.com/uploa...1243523837.jpg

I would make sure the ICV is dry and the connections are solid.

Then reset the code and see if it comes back.

Thanks Jeron, I have a new ICV and when I find a new grommet it will be installed. I had cleaned the old one and can hear it buzz so I know it is not stuck, but it is out of range on it's resistance.

I pulled the #3 plug, I was just going to look until I dropped it in the dirt, so I had to clean it. It ran differently after that.



http://forums.pelicanparts.com/uploa...1243558074.jpg
http://forums.pelicanparts.com/uploa...1243558108.jpg

The deposits on those electrodes look like an unusual color.

Judging from the shape of that top electrode and the recess on the center electrode, that plug looks like it has quite a few miles on it. I would have put in with fresh plugs when I saw that one. Look carefully at the rubber boots when replacing the plugs. I have put fresh rubber on both my '97s. The plugs, however, probably have nothing to do with the rough cold idle.

Those deposits look like sulfur, and it is on the outside of the wire down near the plug hole.


I'm going to change the plugs and the wires too.


This Idle situation started out being present at cold start up and then gradually became constant during idle all the time.

I have just put on a new ICV and it is now very steady.

But on the second start up it was back to erratic idle. Then it sat out in a rain storm and after that a
constant skipping. This problem must have something to do with the water.

I think I did not get the old ICV all the way back in when I cleaned it and that may have caused the constant rough idle and the misfiring, just a guess though.

It turned out to be a bad coil on #3.

Your description with the wet weather and sporadic problem is commonly how a bad coil presents itself.

That is different than the "stone cold start" rough idle which is so common.