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Questions: Stuttering from a stop, spiking Afr's, anything obvious?

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  • Questions: Stuttering from a stop, spiking Afr's, anything obvious?

    My Dad and I recently installed the Pro Flo 4 on my K10 with a 5.3 Vortec (LM7) as a power plant.

    The Install went great with a couple minor hiccups but after about 50 or so miles of driving I have a few questions:

    Starting off from an Idle (Lets say at a red light) The engine seems to stutter a bit, and hesitate for around 1/2 of a second before agreeing with my pedal input and simply taking off
    Would this be a fueling issue or something like lets say a timing issue? I've been watching the AFR's but it seems to stay between 13.8-14.0 (Set at 14.3 for idle and 13.9 for cruise)

    Also, from time to time if I'm coasting along at around 10 mph and give it 10% or so of throttle, the rpm's bounce from idle(Target is 700) to around 1500 and the afr's go from full lean to around 13.0 in cadence with the idle fluctuating. To me this sounded like a fuel pressure issue but I thought I would get some opinions while i'm here.

    I've seen that people use the tablet screen recording app as a data logger with their gauge displays on the Edelbrock App, I'll trying doing this and getting the issue on video to get some more specific details to the experienced eyes on here.

    Any opinions would be appreciated

    JP.

  • #2
    Flat spot from a stop?
    Add 15% Pumpshot in the Acceleration Fuel screen.

    Post cell video for other stuff.

    Comment


    • #3
      Sorry for the late reply.
      I added 15% to the pump shot as you said and it helped but did not get rid of the flat spot, I tried turning it up to 25% and as low as 5% but there was no major difference.

      I managed to get a video of the digital gauges while the rpm's were searching, it does this in gear as well and only when I am between 2 and 5% throttle. Any ideas as to why this happens and how I could fix it? Thank you.

      If the link doesn't work let me know and I will figure out how to change the format(I'm not great with computers)

      Comment


      • #4
        Finally figured it out, here ya go

        Comment


        • #5
          What MAP # are you on ?

          Are you using Edelbrock inectors ? What color band ?

          Fuel PSI looks low....

          Comment


          • #6
            Some need pins #1, and #3 switched on the cam sensor..... basically if it runs like crud switch the wires around.

            The 2 problems people have with LS type motors are:

            1. Not grounding the coils to the heads, and grounding the heads to the firewall/Frame.

            2. GM used 3 different camshaft sensors. Some had switched wires ( some had the wires switched in a "extension harness" ). Switching pins #1 with #3 is the fix.
            At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy

            Comment


            • #7
              Originally posted by 2700 Cast View Post
              What MAP # are you on ?

              Are you using Edelbrock inectors ? What color band ?

              Fuel PSI looks low....
              On the 6012 map, 35 lb/hr injectors, and I have a vacuum reference line run from my Aeromotive regulator so that is why the pressure reads low at an idle.

              Comment


              • #8
                Originally posted by BITE_ME View Post
                Some need pins #1, and #3 switched on the cam sensor..... basically if it runs like crud switch the wires around.

                The 2 problems people have with LS type motors are:

                1. Not grounding the coils to the heads, and grounding the heads to the firewall/Frame.

                2. GM used 3 different camshaft sensors. Some had switched wires ( some had the wires switched in a "extension harness" ). Switching pins #1 with #3 is the fix.
                it runs great other than this issue, I have the coils grounded properly, the cam sensor i'm not sure, would there be any other symptoms if the cam sensor pins are switched around?

                Comment


                • #9
                  Some people get a "no start" condition.....other then that. It will run like crud, because it makes the camshaft signals backwards.
                  At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy

                  Comment


                  • #10
                    I have to agree with the low F/P. Bump it up to 45-46 with eng running and vac disconnected and plugged. See what happens.

                    Comment


                    • #11
                      Originally posted by R573CAR View Post
                      I have to agree with the low F/P. Bump it up to 45-46 with eng running and vac disconnected and plugged. See what happens.
                      I will try that tomorrow and let you know how it goes. Thank you

                      Comment

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