crazy promag issues

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by overkill69, Jul 20, 2015.

  1. GottaGoFaster

    GottaGoFaster New Member

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    In looking closer at the data--I am pretty sure that there is one "major" sq wave followed by 7 "minor" sq waves. I'm guessing that means the grid is probably seeing interference from the coil output on the ign input? Most likely a huge issue . . .
     
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  2. cheyenne

    cheyenne Member

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    on the first full run graph I see gaps or spaces inbetween them. take a close look at the graph. Make sure that your crank trigger ground has a really good ground like back to the battery. Plus make sure the heads are grounded too.
     
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  3. Mike Canter

    Mike Canter Top Dragster

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    The screen shots look good. Did it mess up during that run?
     
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  4. GottaGoFaster

    GottaGoFaster New Member

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    Yes, during that run (and many previous runs) it didnt run clean or build RPM willingly. Basically feels and sounds fat, lazy, sluggish. It may very likely be running extremely rich (very little or no heat showing on plugs, egt's hanging out in mid 700's).

    On a normal "good" run, should I see only a single sq wave peak from each crank trigger input? What I see on my data is 8 sq wave peaks: (a tall one which i assume is crank trigger) and 7 short ones (which could be coil output interference). If you do the math, the tall peaks are timed perfectly to coincide with the timing of the magnet moving past the crank trigger.

    I'm ultimately trying to decide if i should get my fuel system re-flowed, or if i need to hunt elsewhere.
     
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  5. Mike Canter

    Mike Canter Top Dragster

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    I think it is all fuel and you are way rich. Since you have EGT’s then either make the pump loop ten richer or the main jet ten richer and see what the egts and plugs show at the end of the run and go from there
     
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  6. overkill69

    overkill69 Member

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    My issue that this thread was originally about turned out to be a power grid too close to the # 7 spark plug. I shielded the box with steel and cured it. I would shield the white wire to the mag also for sure. Any wire on the grid can be an antenna but most issues are trigger wires. The trigger signal displayed in/out are manipulated by the box and can be misleading. I just worked on a car that had clean signal in and out turning it with the starter but zero fire. Ended up loading a fresh file and it ran fine. It took us a full season to find our problem. Good luck.
     
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  7. GottaGoFaster

    GottaGoFaster New Member

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    Great to have input from the community on these incredibly difficult problems to positively diagnose.

    I will be re-routing the grid's white wire far away from all other conductors. I'll also change to a twisted pair conductor with foil shield which will run from the crank trigger all the way to within 6" of the grid. Maybe overkill--but easily done and cheap insurance.

    Thanks guys.
     
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