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E30 Bucking/Stalling at idle.

Discussion in 'E30 (1984-1993)' started by jlegleiter, May 14, 2009.

    jlegleiter guest

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    E30 Bucking/Stalling

    Ok, here is the scenario.

    1989 325i

    Main and Fuel Pump relays replaced in February.

    In March:
    Fuel Filter
    Ignition Coil
    Dist. Cap

    C101 connector was removed and the harnesses hardwired together in February. Seems like overkill I know, but had you seen the condition of the connector it would make sense.


    This all began on Saturday. I was driving (naturally) and came to a stop light when the car died suddenly. It had not exhibited this behavior so I was concerned. The car restarted with some hesitation and I went on my way. Next stoplight, the same situation after idling for a few seconds. Gradually as I nursed it to my destination, it became more an more frequent. Initially it would die after as much as 30 seconds at idle, but eventually would die immediately after depressing the clutch and reaching idle RPM.

    I was headed to a friend's. At the time this started I was nearer his house than mine, so it only made sense to go there, rather than attempting to turn around and head home.
    I was there for a few hours, waiting for traffic to die down before trying to nurse my way back home. The car started, but cranked slightly longer than usual. Since the problem had only presented itself at idle, I took the highway home rather than surface streets to avoid stoplights. The problem did not reappear that night. I did have to stop at three or four lights on the way home, but did so without incident.

    The next day, the car started, but again with hesitation. Made it to work without a re occurrence of the problem. On the way home however, while at cruising speed, the car will buck, and RPMs drop slightly, check engine light flashes, then power returns.

    This is now becoming more and more frequent, and I don't want to drive anymore than I have to.

    Here is the odd thing though, the only code than the computer spits out is 1263 - Evaporative Purge Valve. Now, from what I can tell, that particular fault should not produce these symptoms.

    I have swapped in a spare DME I keep around, just to rule that out, without change. I have even disconnected the purge valve altogether just to see if that would produce a change in symptoms. It did not.

    I have two thoughts at the moment.

    The first being that the fault code produced by the DME and the bucking/stalling symptoms are unrelated. Perhaps the valve was already faulty and the DME has stored that code, but is not producing another code for the incidents of stalling.

    The other is that somewhere in my harness there is a short, causing not only the stalling but also the to DME to read the fault incorrectly.

    CPS keeps coming to mind, though I am baffled by the 1263 code being thrown.

    • Member


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    Is the idle rough before cut off? Check for vacume leaks. Cracked hoses and connectors can cause the symptoms described. Clean your Idle air control valve while your at it. If you are convinced it is the ignition system check to condition of the spark plugs for oil or anything else that may indicate a valve cover gasket leak, etc. The random nature makes me think vacume leak though.

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