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Starting Mondial: gas causes revs to lower, slow down light later on

Discussion in 'Technical Q&A' started by rascalif, Jun 7, 2004.

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  1. rascalif

    rascalif Karting

    Dec 20, 2003
    82
    Southern California
    #1 rascalif, Jun 7, 2004
    I've read all the threads on the slow down light and am going to look into the recommendations (coil, digiplex, ECU Cat, etc.), but there was one thing I experienced that I didn't see anywhere. Yesterday I started up my '86 Mondial 3.2 and noticed that the battery light was on and idle was a bit low. Normally I would lightly tap on the gas, the revs would go up and problem solved. However, this time when I tapped on the gas, the engine actually started to hesitate and the RPM went down. So I just waited about 15 seconds and the idle went up by itself, and everything was ok. However, after about 10 minutes of driving my Slow Down light went on and the power went down (I'm assuming one of the cylinder banks shut off). I was only doing about 50 on fourth gear. I just eased off on the gas and the Slow Down light went off and I was ok getting home.

    Sounds like an electrical problem, but if anyone else has seen this I'd appreciate any advice. Thanks!
     
  2. don_xvi

    don_xvi F1 Rookie

    Nov 1, 2003
    2,934
    Outside Detroit
    Full Name:
    Don the 16th
    #2 don_xvi, Jun 7, 2004
    Sounds more like a fuel delivery issue. Like too much. I guess your car would be injected with Motronic? Something is causing it to bog down pig rich, and when you're driving all that extra fuel is being burned in the catalyst. It'll ruin the cat quickly and melt it (furthering your performance problems) if you don't take care of it.
    I still haven't really figured out these injection systems, but your friendly Euro car mechanic will be quite familiar with it... But I'd suggest towing there lest you should be buying a new catalyst.
     
  3. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    #3 snj5, Jun 7, 2004
    86 Mondial - Bosch K-jetronic mechanical injection.
    Sounds like maybe low voltage causing low fuel pump performance causing low pressure at the injectors. Very lean - very hot - slow down.
    Replace the battery and ensure the charging circuit is ok - Sometimes a failing voltage regulator or altenator may cause this.

    If you lost power, then the slow down light came on a bit after, you lost a coil pack. Check ignition on both banks. If you were able to slow down and the light went out, you didn't lose a coil pack. See above.

    Let us know.
    Good luck
    Russ
     
  4. rascalif

    rascalif Karting

    Dec 20, 2003
    82
    Southern California
    #4 rascalif, Jun 7, 2004
    Thanks all. I'm sending the car to my mechanic tomorrow with this feedback and will post back what he finds out.
     
  5. rascalif

    rascalif Karting

    Dec 20, 2003
    82
    Southern California
    #5 rascalif, Jun 7, 2004
    This brings up another question. Is the loss of power a safety feature (ie, triggers automatic shutdown of a cylinder bank), or is the power loss symptomatic of another problem?
     
  6. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    #6 snj5, Jun 7, 2004
    Loss of power, especially a bank loss is not a safety feature with the single injection distributor and dual ignitions. Quite the opposite. If you have power loss, it's the problem, and could get worse.

    If your loss of power is due to a single bank ignition loss, the injection on the dead side continues to function, blowing unburned air and gas into the exhaust where it meets the hot stuff from the good ignition side. It all burns rather hot in the cat, setting off the slow down light, and if persists, a cat fire.

    You describe being able to slow down and the light going off. This is not the classical bank ignition failure. It's usually all or none. Will be very interested to learn what the peoblem is, as this is a bit different presentation than I've seen or heard of before.

    I will say it's amazing how many Mondial ills are cured by a new battery.

    Good luck, and we're all rooting for you!
    best
    rt
     
  7. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,689
    North shore, MA
    Full Name:
    THE Birdman
    #7 Birdman, Jun 7, 2004
    Rascalif,
    Seems to me you posted a question recently about your clock resetting when you started the car and the indications were that it was a bad battery or charge on the battery. Now here is another symptom that could be battery-related. I would replace that battery and have the alternator checked. A replacement battery is very cheap. Replacing the cats is very expensive.

    Birdman
     
  8. rascalif

    rascalif Karting

    Dec 20, 2003
    82
    Southern California
    #8 rascalif, Jun 9, 2004
    Well, installed a new Optima Red Top last night and reset the cat ECU. The car runs fine but I'll try to replicate the condition that caused the original problem by driving around for a while and seeing if the Slow Down light goes on. Also, the clock problem is still there so it looks like the battery wasn't the problem.

    I'm sending the car to the mechanic tomorrow and will post the findings here.
     
  9. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    #9 snj5, Jun 9, 2004
    I'm hoping the car will run just fine without the slow down light. It could have just been a poopy battery, but still need to check the charging circuit (alternator, voltage regulator, fuses).

    The clock is screwy anyway - could be a secondary bit of mischief. Mine got mad at me after I let the battery die and will not do anything now but a stopwatch function. Better now anyway since I have a clock in the radio:
    "... a man with a clock knows exactly what time it is; a man with two clocks is never sure..."

    By the way, with Bosch K-jetronic you do not need to 're-set' the cat ECU; that is a Motronic 'feature'.

    Good luck! Let us know!!
    best
    rt
     

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