Rough Idle

J8MACDON

MEMBER
1986 BMW 325
6 CYL
2WD
MANUAL
262,000 MILES

I have a 1986 6cyl BMW 325e and am having trouble with the idle. When you start it the engine sounds fine but the idle is pulsing up and down then it cuts out after a minute or two. If I get it on the road or hold it at 1500 rpm it sounds great, with no sputters or anything. The exhaust is burning a little soot when it is idling by itself (maybe due to not burning the fuel at a constant rate?) But is not blowing blue or anything when running at 1500 or more. It feels like either its not getting its gas or a clogged catylitic converter or muffler. I bought the car second hand so I have no idea of its exhaust/maintenance history but the exhaust has been running a little bit louder than it should since I got it a year ago.
Any suggestions to rule out what it isnt would be great, and there is a full tank of gas in it so its not a broken gauge. Could dirt in the lines cause this?

Thanks,
Justin

1 Reply

DOCHAGERTY

MECHANIC
9,601 POSTS

The idle issue is typical of the ETA motors that have a compromised idle control module/valve. It can be quite expensive to remedy the problem. How would you like to proceed? The new ICV/ICU are several hundred each new and if purchased as used parts, can be no better than what you have now. 13411707395 is the part number for the L-shaped valve and I cant find the number to pull up for the ICU right at this time. Realoem. Com sells the ICV for $328 and the ICU is about the same for retail cost, I will try to post the part number for the ICU later today.