High rev mis fire

Discussion in 'PSI Superchargers Tech Questions' started by jerry hunt, Aug 19, 2009.

  1. jerry hunt

    jerry hunt New Member

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    We developed a mis in the pass couple of outings, Seems when the engine see 7000 rpm it starts to cut up . motor 526 kb hemi veney head 14/71 superman msd 44 mag 30 deg of timing. could it be a coil wire or coil going bad, ignition box etc... just looking if anyone else has had something similar happen and where to look thanks for your response Jerry Hunt
     
    #1
    jerry hunt, Aug 19, 2009
  2. Mike Canter

    Mike Canter Top Dragster
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    How long have the ignition wires been on the car? You are thinking in the right direction because 90% of those type problems are ignition wire related. If the wires are more than half a season old then they should be replaced if you race alot. The coil wire for sure because it works eight times more than a sparkplug wire. According the MSD the wires can check good with a meter but the insulation can break down and jump the spark to anywhere.
     
    #2
    Mike Canter, Aug 19, 2009
  3. jerry hunt

    jerry hunt New Member

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    thanks Mike , the wires have about 30-40 runs on them , coil wire about 12 cap and rotor all season. thanks again Jerry Hunt
     
    #3
    jerry hunt, Aug 19, 2009
  4. jim phillips

    jim phillips ta/fc

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    i had some wierd shit like that going on once it was the coil wire plenty of spares now
     
    #4
    jim phillips, Aug 19, 2009
  5. JT Heslink

    JT Heslink New Member

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    I had a coil wire start to go bad after about 20 runs last year. I am now tracking the runs and will change it frequently.
     
    #5
    JT Heslink, Aug 19, 2009
  6. caseyspradlin

    caseyspradlin Member

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    I had a grounding problem on msd ignition box that caused the same thing, a high rpm miss. make sure grounds are the proper wire guage and contacts are clean of paint.
     
    #6
    caseyspradlin, Aug 19, 2009
  7. big blue oval

    big blue oval Member

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    Im living proof!
     
    #7
    big blue oval, Aug 20, 2009
  8. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    coil wire

    you take the number of runs you have made on your coil wire and multiply it times 8, since it's firing every time. so 10 runs on your coil wire is like 80 runs on your plug wires.
     
    #8
    Will Hanna, Aug 20, 2009
  9. Top Drag

    Top Drag Wally Stelmach TD5560

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    Just a quick note to let you know the same thing happened to me at the dyno at Brad's in Calgary. We chased it for a number of pulls and fianally removed the crank trigger and ran only on the mag. Miss scatter fell to less than 1%. The trigger was brand new from MSD and just put on at the dyno. Hope this helps.
     
    #9
    Top Drag, Aug 24, 2009
  10. mbaker3

    mbaker3 New Member

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    Engine mis-fires

    We had the same thing going on.

    SBC, blown, injected alcohol. Idled ok at home and in the pits during warm up. Took it to the staging lane and did the burn out. Then, going down the track it was popping, cracking, etc., sounded like it was coming apart.

    We hunted fuel issues and loose ignition wires for two days. Happened to touch the battery cables and found they looked good but were not tight!:eek:

    Now it is running fine! I just didn't think to check them first
     
    #10
    mbaker3, Aug 24, 2009
  11. Mike Canter

    Mike Canter Top Dragster
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    You don't need a battery for a ProMag44 unless you run an 8973.
     
    #11
    Mike Canter, Aug 24, 2009

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