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Mondial T bucking

Discussion in 'Mondial' started by GTSRacer, Aug 12, 2004.

  1. GTSRacer

    GTSRacer Rookie

    Aug 12, 2004
    32
    Hampton, VA
    Full Name:
    Olivier F. Raoust
    For some time now, my 89 Coupe has bucked (prancing horse disease? : ) and sputtered when warm. Also it's running very rich with black smoke when accelerating. I'm told that warm-up sensor(s) is/are bad, ie. ECU still thinks car is cold.
    Can anyone shed more light... as in, one or more sensors, location, etc..?
    Any help is greatly appreciated.
    Olivier Raoust
     
  2. Michael B

    Michael B F1 Rookie
    Silver Subscribed Owner

    Apr 28, 2004
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    Michael
    I think you may have a 02 sensor issue.

    Easy to test:

    Right at the oil filter you will see a pair of 2 pin connectors & a pair of rubber booted singe spade connectors. Those connectors (if you follow them) will route right down to the 02 sensors (one in each exhaust pipe). Unplug the single spade connector for each side (or go ahead & unplug all three wires). That will let the 02 sensors go neutral and may cure your rich condition. That test is easy to do, so try that 1st. If your car runs better, then test the 02's or just replace them. Keeping in mind that sometimes the 02's are okay, but the wiring to the 02's can be problematic.

    If the 02 disconnection does not make a change - you can move on to the coolant temp sensors.

    The temp sensors are located under the intake manifold. They are by no means easy to replace, but you can do it @ home if you must. You can just see them through the manifold. They have blue connectors on them.
     
  3. GTSRacer

    GTSRacer Rookie

    Aug 12, 2004
    32
    Hampton, VA
    Full Name:
    Olivier F. Raoust
    Well my car has no cats - bypass pipes, so the O2 sensors are disconnected. And have been since I purchased the car six years ago. I was told by a couple of different tech guys that it didn't affect the tuning...
    I located the temp sensors as described (you're right, a ***** to get to!) and after disconnecting, cleaning and reconnecting the bucking symptom seems to have disappeared. Don't know if it's completely cured the rich running (black smoke at times upon acceleration), but it's certainly a lot better and car definitely runs better when warm.
    Thanks for the tips, though. If you have any more thoughts, I'd love to hear them.
    Olivier
     
  4. Michael B

    Michael B F1 Rookie
    Silver Subscribed Owner

    Apr 28, 2004
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    Michael
    Okay, good news. Thanks for the return post.

    If its fixed, then great. Lets just hope it was a poor connection.

    The black smoke could be from a fuel pressure regulator. If the regulator leaks internally, it will send fuel into the intake & cause the smoke you describe (of course several other things could as well...).

    Again, easy to check. There is a small vacuum line at the further most corner (closest to the fire wall) at the top of the intakes (one line per side). These lines come from the fuel pressure regulators. They can pull off of the manifold easily - then you can check & see if the lines have any fuel in them. If you see fuel in either line - that can cause the condition you describe.

    Run the car for a bit to build fuel pressure, then shut the car off & pull each vacuum line off. If its wet inside of the line, then you need a new regulator (or two). Lots of ways to test them with gauges etc., but this simple step will at least get you closer to a diagnoses.

    As for the 02 sensors... If they go bad they sure can cause some strange running, but if your car likes them unplugged, then keep it up.

    Hey! How does that 3.4 of yours sound with the by-pass pipes?!
     
  5. GTSRacer

    GTSRacer Rookie

    Aug 12, 2004
    32
    Hampton, VA
    Full Name:
    Olivier F. Raoust
    Been away racing this past weekned at MidOhio so didn't have a chance to reply sooner. Thanks for the fuel pressure regulator lines. I'll try it and see.
    As for the sound w/o the cats, well let's just say it sounds like a proper Ferrari! Certainly has a lot more presence, but then again I'm used to my race car and IT is definitely loud! It's a World Challenge E36 BMW, btw.
     

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