Engine run-on after shut down?

Discussion in 'Troubleshooting & Diagnosis' started by engine, Oct 13, 2002.

  1. engine

    engine Veteran Member

    6,319
    0
    Feb 25, 2001
    The ghetto of Brooklyn
    This happened twice to me in the last 2 weeks. Before I shut the car off, I would give it a little gas to rev the engine slightly. When the RPM was at idle again, I'd shut it off. The engine would try and keep running for like a second, but stumbles and then shuts down. After that would happen, i'd start it again and shut down, it wouldn't happen. What does this mean? should I just not rev just before shut down? Otherwise evertyhing is running nice and smooth.

    [This message has been edited by engine (edited October 13, 2002).]
     
  2. rogue9_km

    rogue9_km New Member

    3
    0
    Aug 18, 2002
    wolfeboro, NH, USA
    well it sounds like your running a tad rich, or your throttle plates aren't closing enough at idle, so your diesling. Just a guess.
     
  3. engine

    engine Veteran Member

    6,319
    0
    Feb 25, 2001
    The ghetto of Brooklyn
    yeah, I am running a bit on the rich side, I'll try and close the fuel ratio adjustment about 1/8 turn or so and see what happens. I was thinking there was too much fuel getting to the engine at that time, and with the engine at operating temps, I'd get some combustion even though there is no spark.
     
  4. 80Camaroman

    80Camaroman Veteran Member

    2,675
    0
    Nov 16, 2001
    Beavercreek, Ohio, USA
    Sounds like the idle speed screw needs adjusted. Does your car have an electric solenoid at the side of the carb? Sometimes these will crap out and cause the same problem too. Hope this helps! [​IMG]

    Jim
    '80 Berlinetta
     
  5. engine

    engine Veteran Member

    6,319
    0
    Feb 25, 2001
    The ghetto of Brooklyn
    In Park and the engine at operating temp, my idle is about 1000rpm, give or take 50. In Drive it's about 800 or so. I'm using a dashpot under the throttle bracket on the carb to slow the closing of the throttle blades at very bottom of the closing because the engine would stall if I stomp on it and lift quickly while in Drive. Maybe I have to adjust the travel of the dashpot so that it's right at the threshold...I'll play with that too. Is there a better way of keeping the engine from stalling like that rather than using the dashpot?

    [This message has been edited by engine (edited October 13, 2002).]
     
  6. 73LTtype

    73LTtype New Member

    26
    0
    Jul 7, 2002
    St Louis,MO.,U.S.A.
    i dont know if you have figured this out yet but here is what i learned from a previous vehicle first off to determine if this is it when getting ready to turn off the car do not rev but leave it in gear and let it idle for a minute or two then turn off {still in drive} if this stops youur problem the cause is too hot of spark plug whats happening is your plug is getting so hot that it is glowing red and still trying to burn unspent fuel in your chamber if you are using r44s try to step up to r45s and so on also you could try regapping your current plugs with more gap hope this helps , ryan
     
  7. T_MAC_C

    T_MAC_C New Member

    1
    0
    Nov 13, 2002
    Fayetteville, NC
    are you running a MSD ignition? if you are you need a diod spliced into the regulator. this solved my problem. [​IMG]
     
  8. engine

    engine Veteran Member

    6,319
    0
    Feb 25, 2001
    The ghetto of Brooklyn
    I drove the car today. I wouldn't give it any gas just before I shut down, just let it idle a bit. Didn't seem to run-on. Maybe that's the ticket. Just shut the thing down. BTW, I'm running a stock type HEI ignition-no boxes. Accel distributor with Accel coil and wires. Delco R44ts plugs.
     
  9. 79er

    79er Member

    50
    0
    Nov 3, 2002
    LA, California
    Two things cause dieseling (after run), either the car is running too hot or the idle speed is set too high. The other guy had an interesting point with the plug temperature too high. I would run the stock heat range plug unless you have headers and if so then go to a one step colder plug and gap at .045 either way.
     
  10. engine

    engine Veteran Member

    6,319
    0
    Feb 25, 2001
    The ghetto of Brooklyn
    Can't do that. Stock plug for a 383, Sportsman heads, Holley dualplane and 3310 carb, XE268 cam? But my R44ts are gapped @ .045"
    Car is running at 180*. Idle in park is set to about 1000rpm, 750-800 in drive.


    [This message has been edited by engine (edited November 17, 2002).]
     

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