Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: RPM Signal

  1. #1

    Default RPM Signal

    I just had my car street tuned by a professional shop and it ran awesome. On the way home I stopped for a bit to eat, got back on the road and started having misfires. It got worse the longer I drove it. Found a bad plug wire due to poor header clearance. Threw a spare one on and it improved, but didn't clear up totally when driving and longer I drove it the worst it got. Oh yeah brand new shorty plugs day of tune. My question is this, I only show a crank signal of 125 RPM when trying to start the car. When I installed the unit I got over 400 RPM at crank easy. It also has an erratic RPM on the handheld, but the gauge is more steady. Anyone have any idea where I should start on troubleshooting? I have a 6 Plus MSD box, MSD coil & large cap Chevy distributor.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    24,204

    Default

    Quote Originally Posted by Foxmlee View Post
    On the way home I stopped for a bit to eat, got back on the road and started having misfires. It got worse the longer I drove it. Found a bad plug wire due to poor header clearance. Threw a spare one on and it improved, but didn't clear up totally when driving and longer I drove it the worst it got.
    You should've also cleared the corrupted Learn Table.

    My question is this, I only show a crank signal of 125 RPM when trying to start the car. When I installed the unit I got over 400 RPM at crank easy. It also has an erratic RPM on the handheld, but the gauge is more steady. Anyone have any idea where I should start on troubleshooting? I have a 6 Plus MSD box, MSD coil & large cap Chevy distributor.
    Ensure it's a genuine GM HEI ignition module.

    Defective ignition modules - common problem with MSD 8366 distributors.
    Replace the ignition module with a genuine GM ignition module.
    (This same rationale applies to Ford TFI distributors too.)
    ‒ Ignition module for MSD 8366 Pro-Billet Distributors:
    GM 19179578
    ACDelco D1943A
    http://www.rockauto.com/dbphp/x,cata...CO_D1943A.html
    http://www.msextra.com/doc/ms1extra/...EI_modules.jpg
    ‒ I'd also verify the GM HEI module polarity is wired correctly:
    https://forums.holley.com/showthread...ity#post120395
    http://www.megamanual.com/ms2/GM_7pinHEI.htm
    ‒ Apply heat sink (thermal conductive) paste on the bottom of the module before installing it.
    Often times, dielectric grease is wrongly used and will lead to an overheated (failed) module.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, BBK 80mm TB, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  3. #3

    Default

    On the Learn Table, I didn't hit Transfer Learning To Base, but didn't Clear it before killing the car either. I replaced the ignition module with an ACDelco brand a couple weeks ago, but I did use dielectric grease. Where do I find heat sink paste? I also cleaned up all the grounds on the car and the MSD 6 Plus ground is connected to the negative battery terminal.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    24,204

    Default

    Quote Originally Posted by Foxmlee View Post
    On the Learn Table, I didn't hit Transfer Learning To Base, but didn't Clear it before killing the car either.
    Never Transfer Learning To Base if the Learn Table is corrupted with erroneous values.

    I replaced the ignition module with an ACDelco brand a couple weeks ago, but I did use dielectric grease. Where do I find heat sink paste?
    Auto parts store.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, BBK 80mm TB, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  5. #5

    Default

    Okay, I have done all I can think to do. I replaced the HEI distributor and the car start & ran. Got it up to temp and tried to set timing, but was still acting like it wasn't firing properly. Today I can get spark at coil, but not at plug wire. Rewired it to bypass MSD 6 Plus ignition box and got the same result. Coil fires, but no spark at plug wire. All sensors are reading properly. RPM signal while cranking still only 150 to 175. Anyone have a next step for me?

  6. #6
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    24,204

    Default

    Quote Originally Posted by Foxmlee View Post
    Got it up to temp and tried to set timing, but was still acting like it wasn't firing properly.
    Is the ignition timing synchronized with the ECU or not? This requires a timing light.
    http://forums.holley.com/showthread....ents-Read-This (Initial Checks & Adjustments - Read Step #4)

    Today I can get spark at coil, but not at plug wire. Rewired it to bypass MSD 6 Plus ignition box and got the same result. Coil fires, but no spark at plug wire.
    It seems you have an ignition system problem.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, BBK 80mm TB, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  7. #7

    Default

    I agree with the ignition issues, but I have replaced every component of the ignition system with exception of the coil. I haven't been able to get the car to start to set the timing. When it started yesterday I was by myself, so I never got to sync the timing. This morning a friend came to help set timing, but could never get a good light flash and then it quit all together. What would cause spark not to come out of a new distributor? It acts the same with using a MSD box or not.

  8. #8
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    24,204

    Default

    Quote Originally Posted by Foxmlee View Post
    I replaced the HEI distributor and the car start & ran. Got it up to temp and tried to set timing, but was still acting like it wasn't firing properly.
    Quote Originally Posted by Foxmlee View Post
    What would cause spark not to come out of a new distributor? It acts the same with using a MSD box or not.
    Defective HEI ignition module? See 2nd half of post #2 above.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, BBK 80mm TB, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  9. #9

    Default

    Not that a new part can't be bad, but this is the second GM module I've tried. If it was the module, would the coil fire?

  10. #10
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    24,204

    Default

    Quote Originally Posted by Foxmlee View Post
    Not that a new part can't be bad, but this is the second GM module I've tried.
    Ensure a genuine GM HEI ignition module.

    If it was the module, would the coil fire?
    No, the coil won't fire with a defective ignition module (especially when the module heats up).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, BBK 80mm TB, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
About us
Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR® Sprint® Cup team and nearly every NHRA® Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Headers, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.
Join us