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308FI starts up,runs fine, then lugs

Discussion in 'Technical Q&A' started by pnorman, May 18, 2004.

  1. pnorman

    pnorman Rookie

    Dec 30, 2003
    47
    The day after I last drove my 308FI, it started having this problem. It starts up immediately, runs fine for a few seconds,then the idle drops and it starts lugging with erratic rpm's until I shut it off. Any ideas? Patrick
     
  2. 308GTS

    308GTS Formula 3

    Dec 27, 2001
    2,220
    TN
    2 things to start with.
    Air Aux Valve. It should have a high idle for the first few minutes at 1800-2200 rpm. I think your car also has a Cold Start Air Valve (not the blue harnessed injector). Check that too.

    Then if both check out test your fuel pressures, cold control, warm control, system pressure and while you are there rest pressure.
    As it could be in your warm up regulator.

    IME a rough and bogging idle is the WUR when the car was running well before.
     
  3. Owens84QV

    Owens84QV F1 Rookie

    Oct 2, 2001
    4,480
    Somewhere in NC
    Full Name:
    Greg
    I'd also check the electrical connections to your coils. My coils became really corroded which caused an incomplete burn on one of the banks.

    When things like this pop up, always check the plugs for color and condition...they can shed a lot of light on what's happening inside the motor.
     
  4. pnorman

    pnorman Rookie

    Dec 30, 2003
    47
    I have clean contacts at the coils...I turn off the engine immediately after it starts lugging. I then pull a plug on each bank and their wet with gasoline? What I don't understand is the the engine runs great for a few seconds(high idle,then drops)...Patrick
     
  5. Forza1

    Forza1 Formula Junior

    Mar 20, 2004
    484
    California
    Full Name:
    DC
    Well, if they're soaked with fuel, it sounds like either an ignition problem, or the ECU is commanding a lot of fuel for some reason(perhaps a sensor is giving it wacky readings). I'd replace the plugs, and check the coil/s and go from there.



    -DC
     
  6. Owens84QV

    Owens84QV F1 Rookie

    Oct 2, 2001
    4,480
    Somewhere in NC
    Full Name:
    Greg
    With my experience in the past, I completely agree with Forza1. This is an electrical issue. Something is not causing a complete burn (hot enough spark) at the plug. Go over ALL of the electrical connections from the distributor, ECU, coils, etc. You'll find it.

    If you let the car run too long in that condition, the unburnt fuel will collect in the muffler and will get super hot!
     
  7. Mike328

    Mike328 F1 Rookie
    Rossa Subscribed

    Oct 19, 2002
    2,655
    Boulder, CO
    Full Name:
    Mike
    ...or the unburned fuel will ignite in the already hot catalytic converter, which can (and will) catch on fire. (Tip: If your "SLOW DOWN" light ever comes on, pull over immediately and tow the car to a shop. Been there, done that.)


    --Mike
     
  8. pnorman

    pnorman Rookie

    Dec 30, 2003
    47
    I'm not driving the car until I solve the problem, just starting it up briefly for test purposes... The car is pre o2 sensor...Patrick
     

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