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Engine lugging/hesitation at low speed in 1st gear

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  • Engine lugging/hesitation at low speed in 1st gear

    I have about 800 miles on my car now with the PF4, engine is a Dart 427 w/mild cam, TKO600 trans. The PF4 seems to be working very well other than this one issue I am having. If I am in first gear trying to slowly creep at 5mph through a parking lot I get a bucking and lugging symptom from the engine, causing me to push in the clutch and almost feather the gas. Once I reach 10+ mph and raise up the RPMs it seems to get better. I feel like the engine is almost loading up at that low 5mph speed. If I am at a signal light and just start to take off I have no issues only when I am trying to keep my speed at 5mph in 1st gear.

    I have my idle set at 900 RPMs and IAC is about 14% at normal operating temp
    I would think with EFI I could put the car in 1st gear and let the clutch out and slowly drive it 5-10 mph without hesitation, bucking or lugging?

    Anyone have any recommendations?

  • #2
    Take cell video of the tablet -when it happens.
    Also watch TPS value s ---maybe has a delay while moving gas pedal ?

    Don't get too caught up in the numbers.
    Just give the Engine what it wants &
    Let the numbers be what they are.

    Jim McFarland....

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    • #3
      What throttle linkage do you have. If it's a solid rod, that's a big cause of your issue.

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      • #4
        Originally posted by 2700 Cast View Post
        Take cell video of the tablet -when it happens.
        Also watch TPS value s ---maybe has a delay while moving gas pedal ?
        I will see what I can do, is there anyway I get the tablet to record it while I am driving? The screen is near impossible to see in direct sunlight and I have a convertible car.

        How would I check the TPS value? When car is off press gas pedal and see if there is a delay on the tablet TPS?

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        • #5
          Originally posted by R573CAR View Post
          What throttle linkage do you have. If it's a solid rod, that's a big cause of your issue.
          Yes I do have a solid rod throttle linkage. How would this type of throttle linkage cause this to happen? Even if I release 1st gear and try to slowly creep at 5mph or less with no pedal the car will lug and not run great unless I feather the gas with the clutch.

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          • #6
            Originally posted by Fman48 View Post

            How would this type of throttle linkage cause this to happen?
            I think the big problem with solid rod linkages are that they don't deal well with engine movement relative to the body. A cable on the other hand is flexible and can have some movement between the body and the engine without causing throttle movement. If you search on here you will find many who have had problems with the rod linkage being a headache for them.

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            • #7
              Originally posted by Fman48 View Post

              Yes I do have a solid rod throttle linkage. How would this type of throttle linkage cause this to happen? Even if I release 1st gear and try to slowly creep at 5mph or less with no pedal the car will lug and not run great unless I feather the gas with the clutch.
              You should use the search feature of the forum.

              Changing a rod system to a cable system has "magically" fixed a lot of vehicles on this forum........10 of them off the top of my head.
              In my neighborhood, if you open your hood to check your oil, and the vehicle still runs after you close it.......Then your labeled the Neighborhood Mechanic.
              https://forums.edelbrock.com/filedat...?photoid=42773

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              • #8
                And also use a throttle return spring if you have'nt already.

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                • #9
                  If you want to test the theory, disconnect the linkage at the throttle body and idle around in a parking lot. Let us know.

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