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Thread: Cam Sync Issue

  1. #1

    Question Cam Sync Issue

    Good evening all. I could use some advice on a CAM sync issue. I was driving the Jeep on the highway last Saturday in 4th gear around 3000 RPM & 70 MPH. All of sudden, the engine shuts off. RPM falls to nothing. AFR goes lean to the moon. Then maybe 10 seconds later, the engine turns back on and all is well. I had no idea what happened and it was very alarming. It has never done this before. Now, this was the first time I held the RPM so high cruising. I would normally have shifted into 5th. Today, it did the same thing again. Engine randomly shut off for like 9 seconds when I cruising about 3000. I was prepared this time and had the datalogger on. I recorded 20 minutes of data hoping to catch this issue.

    Upon reviewing the datalog at home, here is what I have learned:
    - When the RPM dropped and AFR sky rocketed, the following diagnostic signals were doing.
    - Diag 3 stopped climbing and went flat.
    - Diag 6 incremented from 0 to 4.
    - Diag 4 incremented from 1 to 5.
    - After maybe 9 seconds, everything went back to normal.

    My understanding is that I momentarily lost my CAM signal.

    Ignition/Engine info:
    - 2003 Jeep 4.7 Stroker
    A) 60-2 trigger wheel on the harmonic dampener with a custom aluminum sensor mount. It is very solid.
    --- 0° Timing Offset
    --- 12 TDC Tooth Number
    --- 1.0 usec Inductive Delay
    --- Falling edge sensor
    B) OEM cam sensor. (Looks like a distributor with the top cut off.)
    --- Single Pulse, falling edge.
    C) LS2 coil packs on the valve cover.
    --- DIS coil on plug with 4.0 msec Dwell

    This engine and EFI combination has about 200 miles on it. Holley HP ECU controlling mostly Jeep OEM MPFI bits from a 2003 TJ. Wiring harness is completely custom.

  2. #2
    Join Date
    Dec 2009
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    Connecticut
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    Quote Originally Posted by Jeep4.7 View Post
    My understanding is that I momentarily lost my CAM signal.
    So replace the cam sync unit. I owned a 2004 Jeep Wrangler Rubicon (purchased new), and the cam sync units are notorious for wearing out and becoming loose internally (and a ticking noise).
    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/3000 RPM converter, 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

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    Will a CAM sync issue cause the engine to shut off? Is that the expected behavior?

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
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    Yes, if you lose the crank or cam sensor signal, the engine immediately stalls.
    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/3000 RPM converter, 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

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    New cam sensor will be here tomorrow. Hopefully that fixes the issue for me. I'll report back later in the week.

  6. #6

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    Well the new cam sensor did not solve the problem. It happened again last night on the way home from work. It occurred at lower RPM (~1900) this time around. If the cam sensor pulse is coming late, which way do I need to turn the cam sensor? I confuse myself constantly when I think about this.

  7. #7
    Join Date
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    Have you tried a System Log so you can look at your cam & crank sensors?

  8. #8
    Join Date
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    Yeah, you can actually see if you've advanced or retarded the cam signal after rotating it: https://forums.holley.com/showthread...s-amp-Datalogs (Datalog & System Log Information - Read "NOTES") Also, we don't know if your cam sync unit spins clockwise or counter-clockwise internally.
    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/3000 RPM converter, 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

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    Quote Originally Posted by 81 TransAm View Post
    Have you tried a System Log so you can look at your cam & crank sensors?
    The System Logs I grabbed did not show this error, which is frustrating. It took me half an hour to drive home last night and the cam sync error occurred one time. I do not believe I can trigger a System Log based on an error. That would be so nice if I could do that.

    Quote Originally Posted by Danny Cabral View Post
    Yeah, you can actually see if you've advanced or retarded the cam signal after rotating it: https://forums.holley.com/showthread...s-amp-Datalogs (Datalog & System Log Information - Read "NOTES") Also, we don't know if your cam sync unit spins clockwise or counter-clockwise internally.
    I'll read through this link and give it a go. I know I read it before when building the wiring harness. I feel like I've read everything like a million times and I still confuse myself all the time.

  10. #10
    Join Date
    Nov 2014
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    You can activate a System Log and then go for a drive.

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