m20 running rough - BMW Forum

Yakker · 03-05-2007, 07:34 PM

So i just did a headgasket/head replacement, i changed all the gasket and anything that should be replaced with the whole thing. Including throttle body gasket, and all of the stock hose clamps to adjustable clamps on the vacuum system. I went to start it back up today and it was hard starting, finally started after giving it some throttle than it would die imediatly. It won't idle at all without having to hold on to the throttle and constatly moving it back in fouth. Tomorrow i'll be going back and searching something unhooked or whatever, but i'm pretty sure i got everything... Just wondering if there was something commonly missed or if anyone had any clues.

da_bull · 03-05-2007, 08:01 PM

A vacuum would definitely make it idle rough. I would start there with all the hoses and clamps. Clamps for tightness and vacuum lines for cracks etc. But I guess if you did a head gasket replacement you already know that

Yakker · 03-05-2007, 08:21 PM

yeah thats what i was suspecting, it won't idle at all without giving it some throttle, actually quite a bit.... I also had to replace my vacuum purge valve with one from a junk yard cause the dealer wanted like 80 bucks for one. Rediculous for a simple vacuum check valve that you can get for a few bucks for a domestic vehicle, but oh well.

99_528iBlack · 03-15-2007, 03:11 PM

I was having the same problem, and then I couldn't even get the care to start it would kick over and die. I changed the Mass Airflow Sensor and it was a New Car!! It is on the expensive side, I paid 275.00, I have a friend at BMW. There is also a Link "http://www.louv.tv/cars/m5/MAF/" that shows you how to clean it. Hope this helps

Yakker · 03-23-2007, 11:36 AM

Well I haven't really had time to look at things till recently, i've changed all the hose clamps to new adjustable type clamps. But i've started to suspect the idle control valve. It will actually idle with the valve unplugged. I took the valve off and sprayed some carb cleaner in it, shook it around, and emptied it. Tried running it again with no luck, but it actually seemed like it was trying to idle for a second the couple times it died. Any thoughts?

fastshivy · 03-23-2007, 02:15 PM

I am guessing you have an E12? Why did you replace the head gasket? Did it run better before or after you changed it? Is the cam timing set right? What about the valve clearances? What level of experience do you have? Sorry for all the questions, but there can be numerous things to go wrong if not assembled correctly. It would help when you post to state the year and model and as much info as possible.