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M42 idle problem
Posted: Tue Jan 31, 2006 8:42 am
by Matt_M44is
Sorry to be a traitor guys but this is for my e36 m42
But an m42 never the less!! lol
Baasically start it up and it won't idle, 1500 - almost stall - 1500 almost stall etc.
I have to hold at over 1000rpm for 10+ seconds and slowly bring it down to make it idle and then it will idle all day long if un touched.
Same happens when driving if clutch pressed in too long, revs drop and then pic up when in gear.
It is smooth with driving and foot hard down.
Any suggestions??? Quick answer would be nice as someone viewing it tonight ... ahh
Thanks
Posted: Tue Jan 31, 2006 10:42 am
by stuartgallafant
could be a throttle position swith. if thats not working it wont 'click' and it wont tell the DME to make the engine idle.
or could even be an air leak? or an air flow meter?
Posted: Tue Jan 31, 2006 11:11 am
by Geeman
Could be the AFM, an air leak in either the rubber boot or a pipe somewhere, a faulty ICV (common problem) or a faulty TPS. Try looking for air leaks, cleaning the ICV and then try the other stuff.
Posted: Tue Jan 31, 2006 12:57 pm
by Matt_M44is
Are there any simple methods for finding faults in the above parts you have mentioned?
Posted: Tue Jan 31, 2006 1:46 pm
by Geeman
Just look for splits or cracks in the rubber piping. If you find any small leaks, tape it up and see if it makes a difference.
Brendan Purcell's site
see here will help you out with problem finding...
Giles
Posted: Tue Jan 31, 2006 1:55 pm
by Cava
His website also has a good section on fault finding on the ICV if the rubber piping looks ok on your car.
Posted: Tue Jan 31, 2006 2:55 pm
by Matt_M44is
Thanks guys will get onto that when i get home, i'll check for air leaks then have the ICV apart
Hopefully she will run then (fingers crossed!)
Posted: Tue Jan 31, 2006 4:59 pm
by jaistanley
If none of the above work try this:
Take out the cam position sensor and give a damn good clean.
If that doesn't sort it, take off the cam cover and make sure the timing is spot on. The square shaped portion of the cam should have each face at 90 degrees to the head exactly.
When doing my timing chain I reset this timing (it was WAY out) and all my idle problems were resolved. Before this I had the symptoms you desribe except it rarely stalled (unless I let the revs fall quickly when cold). It would hunt like mad, especially when cold and generally be a right pain in the rectum!
Hope this helps..
Jai Stanley