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Thread: Cam signal not showing.

  1. #1
    Join Date
    Aug 2016
    Location
    Oklahoma
    Posts
    17

    Default Cam signal not showing.

    Just got my MPFI together and started. The end goal is sequential injection and I cannot seem to get the cam signal to show.
    Here are my stats:
    440 Chrysler - ProFlow intake, Holley 90mm TB, 36 lb injectors.
    60-2 wheel - Hall-Effect pickup 12V - B12.
    Cam sensor fitted from Jeep 4.0L - 12V -B12.
    LS2 coils

    For the first startup I set:
    Ignition 60-2
    Cam No Sensor
    Output Waste-Spark

    I did my pre-checks and straighten out wiring mistakes, set timing and Inductive Delay, warmed up engine, got to the Learn Table around idle and got it to idle decent. I then set output to from Waste-Spark to DIS, started engine and idled like before. I did a System Log and I have a smooth cam trace and a cam A/D signal.
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    Next I changed cam to 1 Pulse/Fire, tried to start the engine, no spark. I did another System Log and I have no smooth cam trace, but the cam A/D shows a signal.
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    To be inline with the ls W/D tried moving cam/crank sensor to ignition power, 5 volt sensor power, with no signal. Bench tested the cam sensor and it looks OK. I bought a new sensor and bench tested it, same signal as the old one, but replaced it, no signal. Between any change I can set the cam to no cam sensor and fires up and System Log shows a smooth cam trace. Any suggestions?
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  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,711

    Default

    I don't know what's wrong. If your cam sync unit isn't transmitting a signal, troubleshoot the cam sensor, wiring, reference voltage & ground, reluctor, alignment, air gap (LINK), radial run-out problems (LINK), etc.
    3-wire Hall-Effect sensor: http://www.wellsve.com/sft503/Counterpoint3_1.pdf (Understanding/Troubleshooting Hall-Effect Sensors - "Troubleshooting", Page 2)
    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
    Join Date
    Aug 2016
    Location
    Oklahoma
    Posts
    17

    Default

    I've read that article before, but rereading he mentioned monitoring the grounds while cranking. I've done the power & signal, but not the ground. Depending on the honey do's tonight, I'll check.

  4. #4
    Join Date
    Aug 2016
    Location
    Oklahoma
    Posts
    17

    Default

    I checked my wiring and voltage at the sensor at key on, cranking and idling. It was all within .5V of ECU. I Ohms tested the wires to the ECU to the cam sensor. All three were less than .1. Then I went back to bench testing. I put the old sensor on the drive and powered it with a drill. Hooked up the oscilloscope and it showed a good square wave signal. Hooked up the oscilloscope to the new sensor on the car it showed a good square wave signal. Took a looked at the System Log again and it to has the same square wave signal as shown on the Cam A/D. I compared these two signals for a long time and then I realize that I have been looking at the square wave form and not the amplitude. The high voltage was .587 volts and the low was .098 volts. It still shows a nice square wave, but not enough for the ECU to use one 1 pulse. I find it strange that in no cam setting the System Log on cam showed a trace. I can assume that since some GM cam sensors use 5V power that the ECU would need say min of 3V swing for a usable trace on 1 pulse setting? Long story to say my next step is ordering a third new cam sensor.

  5. #5
    Join Date
    Aug 2016
    Location
    Oklahoma
    Posts
    17

    Default

    After 4 sensors (2 standard products and 2 Mopar) with no good signal - bench test or on the car, I took a closer look at Fastman and other setups for RB Chryslers and they show a late '90s Ford 3.0L cam sensor. I'm using the Jeep cam sensor body, but the sensors "looked" close, so I ordered one. Bench tested and showed a signal like I expected connections are different than the Jeep sensor, but it fit in the same housing and the window operated correctly.

    So I installed on the engine, with no cam input, rewired for the Ford unit. The system log showed .3V at low and 10.1V on high,
    then changed to 1 pulse cam. And the system log showed a good signal and trace unlike before. Turned injectors on and cranked for a while and it fired up!

    My lessons are:
    4 new sensors do no not mean they are good sensors.
    and a '99 Ford 3.0L cam sensor will bolt into a '99 Jeep 4.0L cam sensor housing.

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