Rough cold idle - BMW Forum

knole68 · 02-19-2012, 08:04 PM

I just got a 1984 e30 318i and I am trying to hunt down a problem with cold starting. When the temp is around 30 and below it idles very rough and does not accelerate very well. I do not have the problem when the outside temp is up so I was wondering what may be some things to check that may help. Any help would be great thanks.

Lord Vader · 02-19-2012, 08:59 PM

Check all your vacuum lines and hose connections. A cracked vacuum line is usually a cause of a rough idle.

Have you cleaned your MAF or ICV ever?

knole68 · 02-19-2012, 10:23 PM

Both MAF and ICV are newly replaced, will work on the vacuum lines and see if that works thanks.

Lord Vader · 02-19-2012, 11:34 PM

When you check the lines, make sure you feel them and bend them. A crack may not be visible until you move it and bend it.

Jack Dabsy · 02-20-2012, 02:00 PM

knole68 · 02-21-2012, 04:36 PM

Can't find vacuum leak anywhere. This morning it took turn for the worse, would not stay running after it came down from fast idle. This is driving me crazy, I tried to keep it running to warm up but no luck. After a bit I finally ran the battery down, I had to drive my truck to work. When I got home it started right up and is running fine.

Lord Vader · 02-21-2012, 06:31 PM

Is it running fine consitently now? Did it fix itself so to speak?

knole68 · 02-21-2012, 09:21 PM

It seems to run fine when the outside temp is up above 40f. I did find a vacuum line that was plugged with a screw, it was from the vac advance on the distributer. I reconnected it and will try again in the morning. It is supposed to be about 31f so we will see if it makes a difference. i will keep updating the progress (if any) but am open to any suggestions. My wife asked about using a engine block heater but not sure that will matter much.

Lord Vader · 02-22-2012, 09:11 AM

These cars didn't come with block heaters. I've never needed one. Mine has always started in the cold. Starts better in the cold then my GMC.

Keep us posted on what happens. If you haven't already it might be a good idea to check out the link below:
http://www.bimmerwerkz.com/forum/3-s...ice-67616.html

The Bentley Manual is the most detailed service manual for the E30. It may have diagrams or instructions to help with the vacuum lines

knole68 · 02-22-2012, 04:46 PM

I got the Bently manual with the car, and it has helped a bit so far just got to keep going through the steps. The big deal is it only happens in the cold mornings.

rivroshaun951 · 02-23-2012, 06:13 PM

I am not a professional. This is just my opinion. I could be wrong.

Have you checked your coolant temp sensor? This can affect your air fuel ratio. Since you say the condition gets better with temperature change I would look at that as well.

knole68 · 02-25-2012, 09:39 AM

The cold temp sensor is also new, I am still working it but I think the problem is more related to moisture and cold rather then just cold temp.

knole68 · 03-01-2012, 05:00 PM

The problem is definately related to moisture. I drove it the other day and it was 50+ and raining and it had a miss the whole way to and from work (40 miles round trip). Not sure whart is causing this as the distributer is dry. It almost seems like it has to do with the air intake or possible the vacuum problem I mentioned before. I know this it was 21 this morning and dry, it fired right up and ran great all the way to work so I am ruling out the cold side of the problem. I will keep posting as I find things out, please keep giving advice I am very thankfull for it.