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M50 Manifold Cold Start Prob On M3

Discussion in 'E36 (1992-1999)' started by E36M3MIKE, May 21, 2008.

    E36M3MIKE guest

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    ok i posted up bimmerforums but i havent yet gotten a good answer.. when i start my car in the morning or after my car has been sitting for about 6 hrs my car starts up really rough and bogs out if i try to accelerate. i havent GOTTEN A CEL so this is driving me nuts... is this common?:confused:
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    mjweimer

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    Interesting problem.

    Have you done a fuel pressure test? Have you pulled the spark plugs to see if the car is running rich or lean?

    I am assuming that once the car warms up a bit it will run normally?

    Matt

    E36M3MIKE guest

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    yes when the car warms up the car runs perfect. the car has been doing it since i installed the m50 manifold, so i went to active and has them reprogram my comp but still no fix. and yes the car is running a little rich but just perfect. to my knowledge what do you think? spark plugs are new
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    mjweimer

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    My first thought is vacuum leak. I say this because as the car warms up the O2 sensor may be compensating for the extra air by adding fuel. I am surprised this would not set a code but who knows.

    Have you double checked every connection on the new manifold? Hose from MAF to throttle? Brake booster hose tight? Throttle body adapter plate installed properly? Manifold properly seated to the head? You get the idea.

    This is the kind of funny problem that is hard to diagnose without the car in front of you.

    Matt

    E36M3MIKE guest

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    you know what i am going to go buy some starter fluid and test out for leaks... you might just be right :D
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    EuroWerkz1

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    Mike,

    Another educated guess...

    It sounds fuel related to me and like the fuel system is leaking down as the car is at rest. That could mean many things including a weak fuel pump / in tank regulator and in fact I have just seen this problem recently. Hard to diagnose especially since it has not set a MIL but I would like to see the numbers on a cold start and I'll bet you would see some evidence of low fuel volume but maybe not pressure. I'd take it to a shop that can read and record live data as I think it would be money well spent.

    Enjoy

    E36M3MIKE guest

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    SO you are saying it my fuel pump and fuel regulator? should i just change both? my buddy has a scanner at work i will put it on there this week

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