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Thread: Bouncy idle, cold air, dash lights

  1. #1
    Join Date
    Oct 2005
    Location
    Richmond, VA
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    Default Bouncy idle, cold air, dash lights

    Well...I just took my '94 E34 525 in and got whallupped with a $1200 bill to do some general maintenance as well as replace the front brakes (and rotors), replace a front fog light assembly, and replace the control arm bushings. Just the nature of the beast I guess.

    Anyway, there were three things they didn't get to that I would like some input on.

    1) Bouncy idle - While the car is warming up and even moreso on a hot restart, the idle will bounce from 400RPM up to 700RPM. It sounds like I'm using my foot to rev the engine. Once the car is running at normal temperature, it does not do it. About a year or so ago the previous owner had to have all the air intake part replaced becuase something got cracked and cold air was getting in and it was basically un-driveable...Now, what's interesting as I'm thinking about this more is that this problem has been going on for a long time...If there was a lose clamp wouldn't the idle be jumpy all the time? I was thinking it might be an O2 sensor going bad, but I'm not getting any check engine lights...

    2) My rear air vents blows cold. In the winter time it blow super cold air, but when I'm running the AC I'm pretty sure it blows cold air then, too. Could there be a valve that is stuck and not letting any warm air get into the mix for the rear vent?

    3) The lights that light up the temperature and fan controls on the dash work 1% of the time at most. I think I've seen them on maybe 3 times since I've had the car. Typically I'll hit a little bump or something and then they'll pop on, but it's unusual. Hitting the controls does not turn them on. Any thoughts on what I'd need to do to fix it? I haven't taken the dash apart on this car so I'm not sure it's worth attempting.

    Thanks!!!
    Last edited by vaaccess; 10-28-2006 at 09:55 AM.

  2. #2
    Join Date
    Mar 2006
    Location
    Derbyshire, UK
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    Quote Originally Posted by vaaccess
    1) Bouncy idle - While the car is warming up and even moreso on a hot restart, the idle will bounce from 400RPM up to 700RPM. It sounds like I'm using my foot to rev the engine. Once the car is running at normal temperature, it does not do it.
    Mine does this for about five to ten seconds only after a cold start. I suspect a vacuum leak or gummy idle control valve, but haven't yet investigated further. The intakes on the M50 engines involve a festival of rubber pipes and seals that harden, crack, and leak over time.

    Quote Originally Posted by vaaccess
    2) My rear air vents blows cold. In the winter time it blow super cold air, but when I'm running the AC I'm pretty sure it blows cold air then, too. Could there be a valve that is stuck and not letting any warm air get into the mix for the rear vent?
    They're supposed to do that. They're fresh air vents. Warm air comes up from under the front seats. There's a picture in the owner's handbook that shows where cold, heated, and semi-heated air comes from.

    Quote Originally Posted by vaaccess
    3) The lights that light up the temperature and fan controls on the dash work 1% of the time at most. I think I've seen them on maybe 3 times since I've had the car. Typically I'll hit a little bump or something and then they'll pop on, but it's unusual. Hitting the controls does not turn them on. Any thoughts on what I'd need to do to fix it? I haven't taken the dash apart on this car so I'm not sure it's worth attempting.
    Thanks!!!
    Mine does that, too. I'm saving fixing it for a dull weekend. The control panel comes out fairly easily once the radio has been removed. The radio comes out with either odd screws that can be finagled loose with a Torx driver or suitably filed flat blade, or by sticking rods of appropriate diameter down four holes. Once the radio is out, the control panel can be freed by popping it out from the back on the left-hand side.

    1997 535i V8
    5spd, OBC, A/C, cruise, BMW phone, factory M-Tech wheel & suspension, 18" Alpinas

  3. #3
    Join Date
    Jan 2006
    Posts
    370

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    Possible cold start injector? Dirty ICV? could be the o2 sen. Possible loose or shorted connection on the lights?




    Quote Originally Posted by vaaccess
    Well...I just took my '94 E34 525 in and got whallupped with a $1200 bill to do some general maintenance as well as replace the front brakes (and rotors), replace a front fog light assembly, and replace the control arm bushings. Just the nature of the beast I guess.

    Anyway, there were three things they didn't get to that I would like some input on.

    1) Bouncy idle - While the car is warming up and even moreso on a hot restart, the idle will bounce from 400RPM up to 700RPM. It sounds like I'm using my foot to rev the engine. Once the car is running at normal temperature, it does not do it. About a year or so ago the previous owner had to have all the air intake part replaced becuase something got cracked and cold air was getting in and it was basically un-driveable...Now, what's interesting as I'm thinking about this more is that this problem has been going on for a long time...If there was a lose clamp wouldn't the idle be jumpy all the time? I was thinking it might be an O2 sensor going bad, but I'm not getting any check engine lights...

    2) My rear air vents blows cold. In the winter time it blow super cold air, but when I'm running the AC I'm pretty sure it blows cold air then, too. Could there be a valve that is stuck and not letting any warm air get into the mix for the rear vent?

    3) The lights that light up the temperature and fan controls on the dash work 1% of the time at most. I think I've seen them on maybe 3 times since I've had the car. Typically I'll hit a little bump or something and then they'll pop on, but it's unusual. Hitting the controls does not turn them on. Any thoughts on what I'd need to do to fix it? I haven't taken the dash apart on this car so I'm not sure it's worth attempting.

    Thanks!!!

  4. #4
    Join Date
    Mar 2006
    Location
    Derbyshire, UK
    Posts
    872

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    Quote Originally Posted by Felixdacat
    Possible cold start injector?
    There isn't one on the M50. Cold start enrichening is done by lengthening the injector pulse.

    1997 535i V8
    5spd, OBC, A/C, cruise, BMW phone, factory M-Tech wheel & suspension, 18" Alpinas

  5. #5
    Join Date
    Oct 2005
    Location
    Richmond, VA
    Posts
    11

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    Ugh.

    Yesterday when I picked it up it was rainy so I had the wipers on and the windows up and the radio on, etc.

    Today is much nicer and had my windows down...And, what the hell do I hear? A metallic rubbing noise coming from the right front, I believe. Definitely changes with speed and doesn't stop when I depress the brakes. They clearly ****ed something up. Not only that, but twice now when I started the car and started to back up a whining noise that was pretty loud started coming from the front of the car.

    So, I'm obviously taking it back in Monday with a vengenance. Now, my question is, should I avoid driving it today and should I make them tow it in?

  6. #6
    Join Date
    Jan 2006
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    370

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    Good to know. Thanks for the info. That helps me get to know this car also.

  7. #7
    Join Date
    Oct 2005
    Location
    Richmond, VA
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    Quote Originally Posted by DaveVoorhis
    Mine does this for about five to ten seconds only after a cold start. I suspect a vacuum leak or gummy idle control valve, but haven't yet investigated further. The intakes on the M50 engines involve a festival of rubber pipes and seals that harden, crack, and leak over time.
    So, should I care? I mean, is there any negative impact of this "problem" in the long run? It really hasn't gotten any worse in the last year so I'm wondering if I should even bother to spend money on having it diagnosed and fixed...

    [QUOTE=DaveVoorhis]They're supposed to do that. They're fresh air vents. Warm air comes up from under the front seats. There's a picture in the owner's handbook that shows where cold, heated, and semi-heated air comes from.QUOTE]

    Whoa. Awesome. Glad to know that. Guess I should have RTMF.

    Quote Originally Posted by DaveVoorhis
    Mine does that, too. I'm saving fixing it for a dull weekend. The control panel comes out fairly easily once the radio has been removed. The radio comes out with either odd screws that can be finagled loose with a Torx driver or suitably filed flat blade, or by sticking rods of appropriate diameter down four holes. Once the radio is out, the control panel can be freed by popping it out from the back on the left-hand side.
    Hmmm...Maybe I'll take care of it if I ever replace the radio then or have some time to kill...

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