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Thread: High rpms in Park

  1. #1

    Default High rpms in Park

    Hi - everything about my EFI install seems to be working well except for the RPMs in Park running high. Cold itís at 1250 RPMs and Hot itís at 1500. Below are my settings - any ideas? This is on a 1977 Trans Am with the stock 400 L78 engine.

    Engine displacement 400
    Number of cylinders 8
    Camshaft street stock
    Fuel pump type : PWM no regulators
    Air pump equipped no
    Idle rpm target: 575
    Rev limit 4500

    A/F targets
    Idle:14
    Cruise:14.3
    Wot 12.8
    Nitrous off
    Boost 12

    Pump squirt 25%
    Power valve enrich 20

    Ignition timing
    Idle rpm: 675
    Total rpm 2500
    Idle advance 16
    Total advance 34
    Vacuum advance 10
    Vacuum type unported
    Nitrous retard off
    Boost retard 1
    Timing control locked at 15 degrees
    Last edited by dstrosbe; 06-09-2018 at 11:12 AM.

  2. #2
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
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    961

    Default

    IAC steps are at what?
    Sounds like the throttle blades are open too far.

    Gary
    Regards

    Gary

  3. #3

    Default

    Thanks Gary for responding. The IAC count is supposed to be between 5 and 15 on an auto, correct (in gear after being warmed up)? Is that what youíre referring to as IAC steps?

    When the throttle blades are setup properly should I be seeing exactly my target IDLE rpm? Even in gear itís closer to 800 than 575.

    Thanks again

  4. #4
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
    961

    Default

    Yes, that is correct. IAC steps are how much, when idling warmed up in gear?

    I would close the throttle blades a bit and recheck idle.

    Do you run an adjustable rotor?

    Gary
    Regards

    Gary

  5. #5

    Default

    Thanks Iíll check the IACs in the morning. Yes Iím running an adjustable rotor 84211 and a ready to run distributor 8563.

  6. #6

    Default

    The weather here is super hot today so Iím not likely to take the TA out. In general - when I do check the IACs - am I supposed to be seeing the target RPM when the IACs are between 5 and 15? I didnít see that in the instructions.

    Thank you

  7. #7

    Default

    Fixed the issue after closing up the throttle blades quite a bit. 700-750 in gear, 750-800 in Park.

    Do I need to reset the system after making the IAC adjustments?

  8. #8
    Join Date
    Jan 2010
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    Default

    Sounds ok, just drive it now.
    Regards

    Gary

  9. #9

    Default

    So the RPMs are under control now. However I started having trouble starting the car after fixing that issue.

    I went back and adjusted the IAC so itís at about 9-13 in drive warm now. Now it starts quickly.

    However when starting it cold, it stalls when quickly shifting into gear. After a few times starting it, it does eventually hold but Iíd like to see it hold on the first time.

    Currently target RPMs are at 700/800. To fix this issue should I raise up the targets? Anything else I should adjust?

    Thanks

  10. #10
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
    961

    Default

    A Moderator or Tech might offer some further advice.
    I've read somewhere the target rpm is 700 minimum.
    It is an electronic carburetor, as far as the engine is concerned.
    So many variables involved, any engine, which intake does it have, exhaust crossover yes or no, etc etc.
    This list is endless.
    Gary
    Regards

    Gary

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