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Thread: Finally back to my duty cycle question, and now some misses during deceleration.

  1. #11


    Quote Originally Posted by GreenAdam66 View Post
    One more thing I forgot to ask above: anyone got any pointers on how to actually MEASURE fuel pressure during actual driving situations? I have a fuel pressure gauge that I can connect into the system, but I have no clue how I'm going to be able to see and read it during hard acceleration!
    If you have a Super Sniper you just hook up a fuel pressure sending unit to the Sniper and then datalog the fuel pressure. If you don't have a Super Sniper then you would need some other datalogging system to measure fuel pressure as you drive.

  2. #12


    Something like this. Ha, ha.

    Click image for larger version. 

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  3. #13
    Join Date
    Sep 2018
    Grand Rapids, MI


    Quote Originally Posted by gregs69rs View Post
    In the datalog, if you click on the AFR line then the box at the top will display the min, max and average for that data point. Your min AFR on the run was 9.6, max was 23.9 and average was 13.8. Definitely not normal at all. At steady cruise you would probably see +-0.5 maybe? On the WOT blasts it is common to have a lean spike, but not like your datalogs.

    In terms of tracking down RF noise, the two top culprits I think are inadequate engine grounds and not using clean power for the ECU 12 volt trigger wires. A close 3rd is magnetic pickup distributors. Do you have a ground cable from the negative post directly to the engine block? How is the pink 12V trigger wire getting power?
    Thanks, Greg. I'll go refresh my memory on what's grounded to where later today. Same with the +12V trigger wire power source. Too many car projects since I did that work.

    My distributor is the stock GM unit (due to the cable driven tachometer in my car), but I've converted it from points to a Pertronix magnetic trigger unit. A potential culprit? Not quite sure how to remove that potential source of interference other than going back to points.

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