Another rough idle thread

Need technical Q/A then you're in the right place

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TPS
E30 Zone Team Member
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Joined: Fri Mar 06, 2009 11:00 pm
Location: Hampshire

Sun Nov 14, 2010 8:49 pm

My 318i(M40) cabby. hasn't been started for a week, went to start it yesterday, it just turned & turned & wouldn't start, tryed again today, eventually sputtered/misfired into life after a couple of attempts, the problem is it dies straightaway unless the you keep the revs. up, until the temp.gauge is out of the blue. It then idles fine. Blue sensor? Has anyone got any other ideas?

I've noticed occasionaly when driving the car in the past, it will suddenly start misfiring/losing power, for a few seconds, then pick up again,could this be related?

Any help will gratefully received..
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1991 325i Touring Alpine White II
1994 318i Touring Sterling Silver
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b4gga83
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Mon Nov 15, 2010 12:55 am

Don't mean to hijack the thread but my m20b25 is doing exactly the same thing, i have changed the sparks, checked the coil, dizzy, rotor arm as well all is fine there.

Could the problem be related to a faulty afm?
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aeberbach
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Mon Nov 15, 2010 3:08 am

Have you checked the throttle position switch outputs where they plug into the computer? Lots of guides say measure this, measure that... but if your 20+ years old wiring between component and Motronic has corroded, been hacked by an alarm/stereo installer or is otherwise damaged your within-spec readings could mean nothing.

I had an issue with my 325i cutting out a few times per hour, usually on the freeway in heavy traffic which was... inconvenient. The problem went away after I removed the Motronic unit, opened it up and reflowed every solder joint. That was 3-4 months ago and it's been solid as a rock since.
TPS
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Tue Nov 16, 2010 8:44 pm

Clean out the throttle housing with an old Toothbrush & Carb.Cleaner, that cures alot of ill's,but alas not my current problem!
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1991 325i Touring Alpine White II
1994 318i Touring Sterling Silver
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davidt
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Tue Nov 16, 2010 9:08 pm

Same issues with my 325 as soon a the weather gets cold and damp I pull the connector off the AFM and it starts fine definitely temperature issue and have changed the AFM and blue temperature sensor . but does not do it ever time. going to have a look tomorrow let you know if I have any joy
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5six7eight
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Sun Nov 28, 2010 4:08 pm

Did anyone make progress on this? My m20b25 will start OK but then rev lumpy before stalling. It needs constant revs to keep it running. Any ideas?
1989 E30 325i Touring
2006 E63 650i Sport Coupe
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