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Stumble at 1950 rpms......

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  • Stumble at 1950 rpms......

    ​​​​​I have a pro flow 2 efi system #ede35210 on my 302 Ford. It works great.....except... between 1875-1950 rpms , no matter what gear, it acts like a transition of sorts, it stumbles....
    i have tried to tune it out, but no luck, I'm not seeing any thing on the hand held, no fluctuating numbers... I'm not real sharp on computer stuff, any input changes dontd seem to make a difference...
    It did it before,I went to a t5 manual, but the standard trans has made it much more pronounced....
    I could live with it...but the rpm range is right at 62-66 mph...
    It just seems to me to be programmed into the computer to do this....any ideas??? Thanks....dav Da
    Last edited by cline39; 07-15-2018, 10:57 AM. Reason: Spell check

  • #2
    First I'll say that to me, your description alone isn't enough to pin point a specific problem. My background is in engineering where problems are typically approached by either examining data or trying to recreate the problem in a controlled environment so we can analyze it. That said, if this were my car and I had this problem I'd do one of two things. First, let's acknowledge that the problem is likely to be either a fueling or ignition problem. I'm leaning toward fueling but honestly it's 50/50 to be either. Assuming it's just a fueling problem, I'd seriously think about putting a wideband O2 sensor on the car so you can monitor the air fuel ratio. Luckily the performance automotive market is saturated with wb O2 gauges and controllers that are fairly inexpensive so it's really just a matter of picking one you like. I personally prefer AEM but there are many others. If you have a laptop (or friend/relative that has one), AEM makes a wb O2 gauge that actually data logs so you can let it monitor and log AFR while you drive around without having to think about it.

    So that's my first suggestion - add on a wb O2 gauge to at least monitor AFR. The other things I'd consider doing is renting 1 hour of dyno time. Put your car on a dyno and run it at the speed/rpm where the problem occurs. Most dynos will have tail pipe sniffers so you'll be able to monitor AFR while you run the car. Is it lean? Is it rich or are AFRs actually on target? The other thing you can do is very carefully check the ignition timing with a timing light while running in the stumble zone. Make sure that the timing matches what is reported on the handheld and also make sure it isn't doing anything unexpected like bouncing around or drifting or anything else. While running you can also check each exhaust primary with a temp gun to see if a certain cylinder is running at a wildly different temp than the others.

    Long story short, if you really want to sort this out, the best approach would be to do some troubleshooting. Then you'll hopefully pin point the actual problem so you can then address it. Hope this helps.


    • #3
      The Pro-Flo 2 is one of the most "tweakable" systems Edelbrock made for the "street". It's best to read the install manual. Specifically on the IAC settings, and fuel acceleration settings.
      At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy


      • #4
        Be nice if it were just a lean condition occurring at that set point. Maybe you can try a global fuel increase and see if it disappears? All other set points should run fine just on the rich side which is safe.

        As Nate mentioned, the narrow band that is installed is not that helpful. If you look up the AFR curve for a narrow band it is very steep and a transition from lean to rich by means of observing the calibration module LEDs can be misleading. I have been battling tuning issues and recently installed an AEM wide band controller to get actual AFR readings.


        • #5
          Thanks so far for input.... I'm new to this.... I read on page 29 in manual that I can put in closed loop, can I make adjustments with wife driving?? I was not sure about if possible while my mind if possible in the trouble area richen or lean as driving...note amounts, and then when sitting still with motor off I can store those values???


          • #6
            I am considering getting a wideband O2 sensor kit...stand alone weld in O2 and guage.....thinking I could know my exact ratio while driving.....make sense???


            • #7
              When the Pro-Flo 2 came out. A wide band kit was recommended, as a add on. But it was not required.

              You remove the Pro-Flo 2's O2 sensor. Install the sensor from the wide band kit.
              Then connect the output wire from the wide band gauge/controller, to the Pro-Flo 2's sensor input.

              It's been done many times. A "sticky" is posted above.
              At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy


              • #8
                you can make adjustments with the handheld on the fly
                but it is a very coarse map
                if you note each manifold pressure and rpm and then use biteditor when you get home it will work nicely