Rough Idle

[The real Apache]

I've been having issues with this on the Alpina and can't seem to get to the bottom of it, I've swapped out the MAF, checked the inlet and exhaust manifolds for leaks, checked the lambda etc. On diagnostics an Indie found that the return from the MAF was at 2 or 4 volts (can't remember which) when it should have been under 1 volt, they managed to bring it in by partially blanking the MAF, this also improves the idle.
This is beginning to bug me, any ideas?

[The real Apache]

mmmn, idle control valve, that has cropped up before in discussions, how does one go about checking it?

[RT/M]

The real Apache said:

mmmn, idle control valve, that has cropped up before in discussions, how does one go about checking it?

I had the same problem with mine, tickover a bit erratic, i removed the idle control valve, cleaned it with a tooth brush and carb cleaner as much as i could, put back together, perfect now.
I found how to do it on google (advice from PHers)just google Bmw idle control valve, it should give you a run down of how to do it.Also check the hoses attatched make sure there are no splits/leaks.

[The real Apache]

RT/M said:

The real Apache said:

mmmn, idle control valve, that has cropped up before in discussions, how does one go about checking it?

I had the same problem with mine, tickover a bit erratic, i removed the idle control valve, cleaned it with a tooth brush and carb cleaner as much as i could, put back together, perfect now.
I found how to do it on google (advice from PHers)just google Bmw idle control valve, it should give you a run down of how to do it.Also check the hoses attatched make sure there are no splits/leaks.

yeah, i think I found that article, an american one. Unfortunately my engine being a bit of a hybrid seems totally different to the one illustrated

[Neil_Sc]

The real Apache said:

mmmn, idle control valve, that has cropped up before in discussions, how does one go about checking it?

You will have to take out the airbox, the MAF, the upper and lower intake boot down to the throttle body and Idle Control Valve.

It is a good chance to check the upper and lower intake boots for cracks too.

If I were you I would plan on replacing those items as the jubilee clips on the lower boot are a pain in the arse to remove and I ended up cutting the boots off when I replaced my crankcase vent valve a year back.

You can remove the throttle body and ICV and clean them with some throttle body cleaner, I'd advocate changing the gaskets on them at the same time.

Edited by Neil_Sc on Thursday 27th May 15:14

[The real Apache]

Well. I tried, I took out the intake assembly right up to the manifold and it was behind a plate underneath. I tried to take that off but gave up.....manifold off job for this one I think