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Thread: Was running great, now stalling.

  1. #1

    Default Was running great, now stalling.

    Hey Folks. I just installed my Holley HP back in March. Car is a drag race 1995 Camaro. Stockish LT1 with Crank Trigger. The car has been running well and I was getting used to the tuning, etc. Then this past weekend the car wouldn't idle after three runs and was missing a bit in the burnout box. Looked over the ignition wires, Optispark, etc., and cannot seem to find any major issues.

    I'm suspect of the IAC & TPS, as they are original. But IAC shouldn't cause it to stumble in the burnout. I've attached a good run along with a datalog when it died and the Global File. Is there anything I can learn from the diagnostic channels? Appreciate the feedback.

  2. #2


    In general, I would advise getting rid of the Optispark. They are known to be unreliable.

  3. #3


    Yes, I'm aware of the issues with Optispark. Currently I've got a rebuilt unit on the car and I'm only using the Optispark to distribute the spark. Crank trigger is sending the timing signal. I've got no intention of getting rid of the Optispark.

  4. #4
    Join Date
    Nov 2014
    Ont. Canada


    Even in your good datalog it was breaking up at the end of each gear. A misfire will show as a lean spike because of all the unused O2. I would start looking for problems with your ignition system.

  5. #5


    The car has a G-Force 5 speed manual transmission. I stab the clutch and pull the next gear while keeping the pedal floored. I assumed the lean spikes at each gear change were related to the engine momentarily unloading. Also, the rev limiter is set to 7000 RPM. Would the rev limiter be kicking in before 7000 RPM and causing some lean spikes due to killing spark? Thanks for looking at the graphs, 81 TransAm.

  6. #6


    So I pulled the spark plugs yesterday and they are black. I've not spent much time tuning the fuel map for idle and I suspect it's way too rich. I'm going to read up on idle tuning and get that sorted. Hopefully that's the issue.

    UPDATE: Turns out the idle was way rich and fouling the plugs. I put on some 12" collector extensions and let the Holley HP correct the fuel map around idle. Engine is much happier.

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