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  • Accelerator pump shot issue

    Hey I'm having a problem with throttle response with my ProFlo 4 system on my 331 SBF. When first touching the throttle it often hesitates and sometimes lean pops, and this happens when taking off just off idle and also when shifting up (manual transmission).
    I've been adjusting up the pump shot and have it up to 65% increase but this problem still persists and doesn't really seem better than when it was at 0%. When watching the tablet, the AFR often goes over 15 or even 16 during these situations. To me, it seems like the pump shot adjustment isn't making a difference and it feels similar to a carburetor with a bad accelerator pump.

    specs:
    Map 5016_v65
    35lb injectors 58psi fuel regulator

    Also, if I make adjustments on the tablet while the engine is running, do they take effect instantly or on the next startup? Does pump shot take time to learn when increasing or does it instantly increase after an adjustment?

  • #2
    For the first part:

    What's the condition of the TPS. Does it go to ZERO every time you let off the gas?
    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

    Comment


    • #3
      For the second part:

      Could be related to my first post.

      Or......this is going to sound strange. But I have to say it.

      Acceleration Pump ; Only works when you accelerate quickly....... basically mash the pedal down quickly.




      For the last part:

      It's instantly adjusted.........only on the Options that have the "Finish" button does it not go into effect, till you press Finish.
      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

      Comment


      • #4
        Originally posted by BITE_ME View Post
        For the first part:

        What's the condition of the TPS. Does it go to ZERO every time you let off the gas?
        Actually I have noticed the TPS reading 1% occasionally at idle but didn't think much of it and haven't paid attention to it in other situations. So this could be an issue?

        Comment


        • #5
          Originally posted by BITE_ME View Post
          For the second part:

          Could be related to my first post.

          Or......this is going to sound strange. But I have to say it.

          Acceleration Pump ; Only works when you accelerate quickly....... basically mash the pedal down quickly.




          For the last part:

          It's instantly adjusted.........only on the Options that have the "Finish" button does it not go into effect, till you press Finish.
          For the accelerator pump part, what if I shift quickly at 5000+ rpm and push around half throttle in the next gear, would pump shot activate? Under these conditions it will hesitate for half a second or so before taking off nicely.

          (Edit)
          To add to this, I haven't floored it since I increased pump shot to 65% but when it was at 30% it still popped first then launched hard.

          Thank you, it's good to know I can play with it while it's running
          Last edited by BenRMX; 06-09-2021, 12:23 AM.

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          • #6
            Something seems wrong to me because it's pointless for the AFR to go leaner than 14.7 but it does this very often even though my target in all 3 conditions is richer and it's in a situation where the O2 learn is almost always off due to quick/recent throttle change so I thought adjusting pump shot was my only choice. Is there anything else I should look into? Is it possible there's something wrong with the throttle position sensor? To me it seems like pump shot has a delay because right after stumbling for a bit it goes great (if it doesn't pop first) no matter how much throttle I push and no matter what rpm it's at

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            • #7
              have you read the sticky notes above ? have you read the e-tuner manual 3 to 5 times ?

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              • #8
                Originally posted by fleet man View Post
                have you read the sticky notes above ? have you read the e-tuner manual 3 to 5 times ?
                Yes, it takes about 3 or more readings for everything to make sense, then the picture becomes clearer.

                There is a lot of good data in there, also clicking on the " ? " on top right ,gives much valued material.
                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....

                Comment


                • #9
                  Originally posted by BenRMX View Post
                  Something seems wrong to me because it's pointless for the AFR to go leaner than 14.7 but it does this very often even though my target in all 3 conditions is richer and it's in a situation where the O2 learn is almost always off due to quick/recent throttle change so I thought adjusting pump shot was my only choice. Is there anything else I should look into? Is it possible there's something wrong with the throttle position sensor? To me it seems like pump shot has a delay because right after stumbling for a bit it goes great (if it doesn't pop first) no matter how much throttle I push and no matter what rpm it's at
                  As stated above, check to see if the TPS reading goes to 0 at idle. If not you will need a new one and is most likely the problem. (Ask me how I know)

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                  • #10
                    Originally posted by jm73340 View Post

                    As stated above, check to see if the TPS reading goes to 0 at idle. If not you will need a new one and is most likely the problem. (Ask me how I know)
                    It often goes to 1 at idle, but I thought this was okay due to the manual stating that the idle condition is 2% or less throttle and under 1400 rpm. However, the problem I'm having feels like it would be a TPS issue, I'm curious what you went through that led you to this conclusion

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                    • #11
                      Originally posted by BenRMX View Post

                      It often goes to 1 at idle, but I thought this was okay due to the manual stating that the idle condition is 2% or less throttle and under 1400 rpm. However, the problem I'm having feels like it would be a TPS issue, I'm curious what you went through that led you to this conclusion
                      I went through a similar issue to what you describe. When taking off from a stop there was a lean condition and surging for 5-10 seconds until it would level out at the specified AFR. No pump shot adjustments would help. TPS was not returning to zero. Replaced TPS problem gone and new one returns to zero each time throttle is closed.

                      Comment


                      • #12
                        Originally posted by jm73340 View Post

                        I went through a similar issue to what you describe. When taking off from a stop there was a lean condition and surging for 5-10 seconds until it would level out at the specified AFR. No pump shot adjustments would help. TPS was not returning to zero. Replaced TPS problem gone and new one returns to zero each time throttle is closed.
                        Yeah that's pretty much what happens with mine but 5-10 seconds sounds almost undrivable! At worst mine will do it for about 1.5 seconds. Did your TPS stay at 1% or was it even higher?
                        Either way it sounds like the same issue, did Edelbrock cover this as part of the warranty for you?

                        I don't know if this is related but I've also noticed the IAC constantly varies what it's at while I'm not at idle. For example, I've seen it as low as 3% while cruising or sometimes 33%, etc. When idling the IAC seems to function just fine but maybe this has to do with the TPS as well?

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                        • #13
                          All sensors work as a team. If one is malfunctioning, then the system wll not function optimally.

                          IAC is not a sensor, and only works on the Idle RPM range.
                          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

                          Comment


                          • #14
                            Originally posted by BITE_ME View Post
                            All sensors work as a team. If one is malfunctioning, then the system wll not function optimally.

                            IAC is not a sensor, and only works on the Idle RPM range.
                            Yeah I know the IAC is not a sensor, more of a valve. But is it supposed to close completely (0%) when the throttle is open or is there a value it should read on the tablet when I'm in situations other than idle?

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                            • #15
                              It's never fully closed when the motor is running....it's at its widest when the motor is cold.
                              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

                              Comment

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