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  • Popping in the engine

    When I decelerate, occasionally I'll get what seems to be a backfire through the engine. I attached a couple of pictures from the tablet when I was driving the last few days. Does anything look out of the ordinary? Thank you.
    Attached Files

  • #2
    Short FT is adding fuel.

    What is your MAP #?
    Engine combo ?
    Vehicle ?

    Comment


    • #3
      Map is 5025v65
      Here's a link to the engine I'm using, https://blueprintengines.com/product...etor-bp4002ct1
      And it's in a '57 Chevy truck

      Thanks!!

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      • #4
        Go into fuel modifiers & add 20%.

        Make sure its not an exhaust leak causing the backfire.

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        • #5
          BP4002CT1-dyno-chart_1903x.jpg Just some observations, and a couple of questions.

          The power range of the motor looks like 3000 to 6100 RPM......If your using a automatic transmission. Is the stall speed around 2800 RPM?

          I believe they might have used a carburetor when the motor was Dynoed.....They got 10.5" of vacuum @ 950 RPM Idle speed. A EFI system will not only smooth out a ruff running motor, but it will keep it's Idle target RPM when put in gear. So the 950 RPM could most likely be lowered about 100 RPM.......In your screen shoots. It looks like you did just that.

          The 2 pictures you posted:
          The first one looks like the motor is idling, but not in gear.....Vacuum is -13.1, and IAC is 3%.
          The second one looks like the motor is idling, but transmission is in drive....Vacuum is -11.00, and IAC is 56%.

          As stated by 2700 Cast. Both screen shots are asking for a lot of extra fuel.....It's almost like you should try Calibration map #5030. But add the extra 20% first before trying another Calibration map.

          Also. I believe we talked about your timing before. I would revisit the "Spark Control" page. In the lower right hand side of the page, the "Short FT" is displayed. I would watch the Short FT as I would add/subtract "Idle Spark".
          I would also add some RPM's to the "Advance" setting....But it depends on how the truck takes off. I might even lower it in 50 RPM steeps.
          At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy

          Comment


          • #6
            Originally posted by BITE_ME View Post
            BP4002CT1-dyno-chart_1903x.jpg Just some observations, and a couple of questions.

            The power range of the motor looks like 3000 to 6100 RPM......If your using a automatic transmission. Is the stall speed around 2800 RPM?

            Yes, I'm using a 700r4. It's got an upgraded convertor from FTI.

            I believe they might have used a carburetor when the motor was Dynoed.....They got 10.5" of vacuum @ 950 RPM Idle speed. A EFI system will not only smooth out a ruff running motor, but it will keep it's Idle target RPM when put in gear. So the 950 RPM could most likely be lowered about 100 RPM.......In your screen shoots. It looks like you did just that.

            The 2 pictures you posted:
            The first one looks like the motor is idling, but not in gear.....Vacuum is -13.1, and IAC is 3%.
            The second one looks like the motor is idling, but transmission is in drive....Vacuum is -11.00, and IAC is 56%.

            I can't remember, but I believe both photos were taken while in neutral. I know for sure at least #2 was.

            As stated by 2700 Cast. Both screen shots are asking for a lot of extra fuel.....It's almost like you should try Calibration map #5030. But add the extra 20% first before trying another Calibration map.

            Ok, I will try that. I don't want to assume anything, so I will ask. I've only looked at that "page" once or twice. I believe there was a global setting or something like that. Do I want to ensure that is checked when I add/adjust the fuel? I want to add fuel all across the board correct, meaning idle, cruise, and full throttle? Each touch of the button adds 1, does this mean that equals 1%? I read the instructions and it also says to clear uncheck self learn. Do I want to do that as well?

            Also. I believe we talked about your timing before. I would revisit the "Spark Control" page. In the lower right hand side of the page, the "Short FT" is displayed. I would watch the Short FT as I would add/subtract "Idle Spark".

            It's obvious that I don't know a lot about tuning. So I appreciate all the help and advice. When you say I should revisit the spark control, what indicators would I use to adjust the spark one way or the other? I guess I'm asking why would I take away or add spark?

            I would also add some RPM's to the "Advance" setting....But it depends on how the truck takes off. I might even lower it in 50 RPM steeps.

            Thank you guys very much!!!!

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            • #7
              Oh, and I forgot to add, I don't believe it's an exhaust leak, but I will check on that.

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              • #8
                "Ok, I will try that. I don't want to assume anything, so I will ask. I've only looked at that "page" once or twice. I believe there was a global setting or something like that. Do I want to ensure that is checked when I add/adjust the fuel? I want to add fuel all across the board correct, meaning idle, cruise, and full throttle? Each touch of the button adds 1, does this mean that equals 1%? I read the instructions and it also says to clear uncheck self learn. Do I want to do that as well?"

                You only need to add fuel ( or remove fuel ) at what ever section is asking for more/less.....Global setting is when all 3 sections are acting the same.
                Yes. It always shows percentage.

                "It's obvious that I don't know a lot about tuning. So I appreciate all the help and advice. When you say I should revisit the spark control, what indicators would I use to adjust the spark one way or the other? I guess I'm asking why would I take away or add spark?"

                At idle with some camshafts ( low vacuum ones ) you get lean ( needs more fuel ) spikes at the O2 sensor. You can sometimes adjust, some of it out by adjusting the timing, fuel, and IAC/PCV valve.....Yes that's a lot of options. But on low vacuum motors, it just requires more tuning at idle speeds.

                Anyway.
                You can try taking some timing out. 2 degrees at a time. Like in the top picture. Timing/IAC/Long FT are all lower then the second picture.
                At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy

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