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Thread: Engine runs in coil mode, but not HEI mode.

  1. #1

    Default Engine runs in coil mode, but not HEI mode.

    Hi, I recently installed the Commander 950 with a large cap HEI 7 pin module. The truck will start, but stalls instantly after. I've selected HEI computer controlled distributor. So I tried it with a tach signal using same distributor, and selected the coil settings in the program, it fires and runs with this setting. I had the module tested and works fine, tested continuity on wiring for the 4 pin distributor plug, and it all rings out fine. Any ideas? Thanks!

  2. #2
    Join Date
    Dec 2009
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    That's strange. A genuine GM small cap HEI (computer controlled) ignition module always works well with the "GM HEI (or other 12V square wave)" selection mode. Maybe it's wired wrong or something else.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3

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    Well, I replaced the distributor with the GM small cap computer controlled, still doing the same thing? Am I missing something in the programing that's different between "Coil -" & "GM HEI (or other 12V square wave)" settings? Thanks!

  4. #4
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    Quote Originally Posted by Naphead View Post
    Am I missing something in the programing that's different between "Coil -" & "GM HEI (or other 12V square wave)" settings?
    Yes, they're entirely different ignition type settings. Read pages 25 & 75 of the Holley C950 manual:
    http://documents.holley.com/techlibrary_r10149-7.pdf (Holley Commander 950 Pro Manual)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  5. #5

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    Turns out the blue/white wire was pinned into the wrong location on the ECU. I placed it in the correct spot, and if fires up & runs! Thanks for responding!

  6. #6
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    17,638

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    You're welcome. Thanks for the update.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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