rough idle

[newbeemeer]

I recently purchased a 1985 735i. My very first BMW, and I must say that I am very happy with my purchase. I may have paid a little more than the car was really worth, but since I could drive and see the car before buying ( as opposed to buying one on eBay ), I think that I made the right choice in the car that I now own. It came from FL and it is in VGC.

What I have noticed is that the idle is rough when the engine is at operating temp. When cold, the rpm's are even, but when the car is running after a while, it seems to be having trouble keeping a smooth idle speed, where it jumps up from 500 rpm a bit and it almost sounds like it is going to stall itself. Any ideas? Thanks in advance!

[libertylover]

First off, a Beemer is a BMW motorcycle; a Bimmer is a BMW car. (I didn't know this either until I owned a BMW-1993 740iL.) So, consider your wrist slapped!

There's a lot of things that can cause a rough idle including some of the sensors like the Oxygen Sensors. Start with the basics though, plugs, plug wires, distributor cap, fuel filters. You might need to adjust your valves on that big six. I know they need it regularly. Here's a link of how to do it (and lots of other stuff):
http://www.nmia.com/~dgnrg/page_2.htm

It might be worth the money to have it hooked up to an electronic diagnostic machine. When they give you their report you may be able to do some or all of the work yourself.

Fortunately, there's a lot of internet help for these cars on forums like this one. Another good one is at www.roadfly.org.

[newbeemeer]

Hey libertylover!

Thanks for your reply. I poked around in and around the engine, looking for loose Vac lines, and found one, which was under the air intake manifold to be cracked and barely on the barb fitting, and another which was plugged off for some reason (desperate mechano?). Anyway, idle much smoother now, and start-ups seem to be a lot better. Have you seen this item on ebay? It is a 5 CD set to troubleshoot and repair BMW's. Check it out! Thanks NBer.

Originally Posted by libertylover

First off, a Beemer is a BMW motorcycle; a Bimmer is a BMW car. (I didn't know this either until I owned a BMW-1993 740iL.) So, consider your wrist slapped!

There's a lot of things that can cause a rough idle including some of the sensors like the Oxygen Sensors. Start with the basics though, plugs, plug wires, distributor cap, fuel filters. You might need to adjust your valves on that big six. I know they need it regularly. Here's a link of how to do it (and lots of other stuff):
http://www.nmia.com/~dgnrg/page_2.htm

It might be worth the money to have it hooked up to an electronic diagnostic machine. When they give you their report you may be able to do some or all of the work yourself.

Fortunately, there's a lot of internet help for these cars on forums like this one. Another good one is at www.roadfly.org.