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Thread: Possible problem with cam & crank signal.

  1. #1

    Default Possible problem with cam & crank signal.

    Having a problem with the car cutting on & off under hard loads most of the time. There has been several times the car will shut down in the middle of a pass and suddenly come back to life & run. Other times it will just blubber and loose power and then try to come back to life. Then shutdown again. It has been a frustrating few weeks to say the least. Run down on setup as follows:
    SBF with Holley HP
    Large Vortech Side Slinger blower with crank bracing
    Innovators West 4x balancer with magnets built-in
    Innovators West timing pointer and crank sensor mount
    Holley Hall-Effect crank sensor with a 58° Reference Angle
    Ran in sequential using the distributor as a magnetic cam sensor at 185°
    1 Pulse/Fire, Digital Falling
    Inductive Delay 270 usec
    Cam Sensor, Single Pulse, Magnetic Type
    Minimum Voltage 0.35V, Filtering 1
    Points Output, Dwell Time 2.0 msec

    I've read a lot of similar problems on this board, but nobody updates their findings and fixes. Car ran fine a year ago, only change has been the actual block & crank. I believe I've been experiencing cam & crank sensor stacking and have been trying to find a happy medium. Car will leave hard then fall out, and then other times it'll have trouble leaving withing 30 feet and 6000 RPM (not exact). I've even gone so far as to run the car without the cam sensor in Bank-To-Bank, and the car will rev well & clean. But will again shutdown within a 100 ft of the starting line. It will come in & go out several times through the run. I've enclosed pics of a System Log. The signal looks good while revving, but on idle it tends to be close to stacking. If I move the cam sensor the other way it will do the opposite, it'll be good at idle and close to stacking while revving hard. The distributor is locked out and welded. Like I said, we ran this car with the same setup for a few years turning 8000 RPM and no problems. The changes do not seem to be enough to cause this problem. Any help would be appreciated and I'll provide anymore info that is needed. I also have datalogs that show the occurrence.
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  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,725

    Default

    What's the crank sensor air gap? I prefer Hall-Effect crank & cam sensors.
    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, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 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/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

  3. #3

    Default

    Crank sensor air gap is .035". Holley Hall-Effect crank sensor and I'm using the magnetic pickup in the distributor as the cam sensor, at 185°. Crank Reference Angle based off of 50° BTDC. Adjusted to 58° to sync timing. Distributor dropped in at 26°, which is the most timing I run under hard load.

  4. #4
    Join Date
    Jul 2014
    Location
    Aptos, CA
    Posts
    99

    Default

    I ran into a similar issue with a MSD 2358 installed in a customer car. Car ran fine then would just quit. Wait, restart and run fine. This happened multiple times and finally quit while just idling in the shop. I started with some basic test procedures to insure the ECU was getting current, and fuel system was working properly at the time, so I knew what to look for. Turned the engine off, waited and restarted. Ran until it just quit and noticed all parameters were good, except, the LED on the distributor went out. This was on the MSD 2348 Hall-Effect cam sensor. I found that wiggling the wires would make/break the circuit. Started the engine again and wiggled and could make it run/quit by moving the wires. Replace the sensor and all is well again.

    I know this isn't the same setup you have, but maybe give you an idea on what to look for. Fixing is easy, finding is challenging.

  5. #5

    Default

    I agree that finding the problem is challenging. This thing has been driving me nuts. This setup ran fine on the last engine it was on in the car. I broke the block and built a new Dart based block engine. I used a new crank and an Innovators West style timing pointer with a built-in crank trigger mount. I'm using the same Innovators West damper with the built-in magnets that was on the other engine. Same MSD billet distributor setup as a cam sensor at 185° BTDC. We'll have the problem where it shuts down in sequential, and if I switch it to Bank-To-Bank, it'll stumble also. It seems the crank signal moves under load, to the point it's stacked with the cam signal at times, but if I put it in Bank-To-Bank it shouldn't matter about the cam signal and it'll still stumble. It'll leave hard, but get out about 1 or 200 feet and just stumble, but I've had a few passes where it seems to be OK. It's killing me, LOL.

  6. #6
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,725

    Default

    (Outlawstang88, please don't type your posts like you're texting. It takes me a long time to edit it. At least use Spell Check before posting.)
    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, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 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/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

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