Rough Idle when cold and in drive
Thread Starter
Junior Member
Joined: Sep 2007
Posts: 56
Likes: 0
2002 C32 AMG
Rough Idle when cold and in drive
Yes.. another C32 with a rough idle issue.
Car was running fine then all of a sudden developed a very rough idle when cold. When the car is in neutral it is OK and you can feel it slightly in reverse.
After driving around for awhile (20-30 minutes), it usually goes away or is not nearly as noticeable. Would motor mounts get better after driving for awhile?
- Occurs when cold
- Really bad in drive (not bad in reverse, OK in neutral)
- Goes away after driving awhile
The air filters are clean. I replaced the plugs and even went as far as to replace all the coil packs and wires.
I connected an OBD scanner and there were no stored codes. I played with it a little and the only thing I noticed was that the timing appeared to be varying alot when it was idling in neutral. The car felt smooth but according to the scanner the timing was moving around about 6+ degrees. Not sure if this is normal as I never looked at it previously.
Is it worth paying someone with the Star diagnostics to scan things? I have read a ton of posts and they point all over. Any ideas?
Thanks!
Chuck
Car was running fine then all of a sudden developed a very rough idle when cold. When the car is in neutral it is OK and you can feel it slightly in reverse.
After driving around for awhile (20-30 minutes), it usually goes away or is not nearly as noticeable. Would motor mounts get better after driving for awhile?
- Occurs when cold
- Really bad in drive (not bad in reverse, OK in neutral)
- Goes away after driving awhile
The air filters are clean. I replaced the plugs and even went as far as to replace all the coil packs and wires.
I connected an OBD scanner and there were no stored codes. I played with it a little and the only thing I noticed was that the timing appeared to be varying alot when it was idling in neutral. The car felt smooth but according to the scanner the timing was moving around about 6+ degrees. Not sure if this is normal as I never looked at it previously.
Is it worth paying someone with the Star diagnostics to scan things? I have read a ton of posts and they point all over. Any ideas?
Thanks!
Chuck
Senior Member
Joined: May 2010
Posts: 380
Likes: 0
From: Seattle, Warshington
2005 C55, 2006 Ram 2500 MegaCab diesel, sold 2001 Dodge 2500 Cummins, sold 87 190e-16v, sold 97 e420
Yes.. another C32 with a rough idle issue.
Car was running fine then all of a sudden developed a very rough idle when cold. When the car is in neutral it is OK and you can feel it slightly in reverse.
After driving around for awhile (20-30 minutes), it usually goes away or is not nearly as noticeable. Would motor mounts get better after driving for awhile?
- Occurs when cold
- Really bad in drive (not bad in reverse, OK in neutral)
- Goes away after driving awhile
The air filters are clean. I replaced the plugs and even went as far as to replace all the coil packs and wires.
I connected an OBD scanner and there were no stored codes. I played with it a little and the only thing I noticed was that the timing appeared to be varying alot when it was idling in neutral. The car felt smooth but according to the scanner the timing was moving around about 6+ degrees. Not sure if this is normal as I never looked at it previously.
Is it worth paying someone with the Star diagnostics to scan things? I have read a ton of posts and they point all over. Any ideas?
Thanks!
Chuck
Car was running fine then all of a sudden developed a very rough idle when cold. When the car is in neutral it is OK and you can feel it slightly in reverse.
After driving around for awhile (20-30 minutes), it usually goes away or is not nearly as noticeable. Would motor mounts get better after driving for awhile?
- Occurs when cold
- Really bad in drive (not bad in reverse, OK in neutral)
- Goes away after driving awhile
The air filters are clean. I replaced the plugs and even went as far as to replace all the coil packs and wires.
I connected an OBD scanner and there were no stored codes. I played with it a little and the only thing I noticed was that the timing appeared to be varying alot when it was idling in neutral. The car felt smooth but according to the scanner the timing was moving around about 6+ degrees. Not sure if this is normal as I never looked at it previously.
Is it worth paying someone with the Star diagnostics to scan things? I have read a ton of posts and they point all over. Any ideas?
Thanks!
Chuck
Thread Starter
Junior Member
Joined: Sep 2007
Posts: 56
Likes: 0
2002 C32 AMG
Perhaps. I had an injector clog once and it triggered a CEL and the car basically went into a limp mode. FI cleaner worked in this case. With the injector clog it really hurt w/o throttle and not idle. Right off idle, in drive and everything smooths out.
I'm leaning toward motor mounts but I have no idea why it would smooth out after being driven around awhile.
I see some oil leaks on the valve covers so a vacuum leak is possible but again why only at idle in drive and not reverse? Are there any vacuum lines connecting to something that is only open at idle? EGR valve?
Chuck
I'm leaning toward motor mounts but I have no idea why it would smooth out after being driven around awhile.
I see some oil leaks on the valve covers so a vacuum leak is possible but again why only at idle in drive and not reverse? Are there any vacuum lines connecting to something that is only open at idle? EGR valve?
Chuck
Member
Joined: Sep 2008
Posts: 173
Likes: 0
From: Vegas
02 C32
I searched but couldn't find your DIY; have you posted it yet? I think I may have the same issue and would like to see the procedure for diagnosis and replacement. Is there any direct way to diagnose faulty motor/transmission mounts, or must it be inferred from the vibration felt while sitting in the car?
Thanx!
EDIT: Please disregard; I found your DIY by searching for threads posted by you. Oddly, the forum search feature didn't turn up your post...
Thanx!
EDIT: Please disregard; I found your DIY by searching for threads posted by you. Oddly, the forum search feature didn't turn up your post...
Last edited by MountainStone; Mar 29, 2012 at 02:13 PM.
