GT350 - low ECT, poor power, misfire codes

Discussion in 'Drivetrain, Exhaust and Electrical' started by YellowJacketBoss302, Apr 29, 2018.

  1. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    So, at the last track event (barber, Chin, April 7,8) some bad things happened.

    1. ECT was low. Even on the track ECT was below normal operating temp for portions of many laps. Off the the track check engine light and low temperature codes appears. Ford replaced the thermostat - this is the third replacement. They say it was jammed up in the wide open position. So far they have no theory as to why this keeps happening.
    2. During portions of many laps (sometimes coinciding with low temp) the car felt like it went into a kind of limp mode. Later in each lap it would be back to normal.
    3. Car threw a number of P0xxx codes (general and several specific misfire codes)
    Dealer has changed coil packs, performed neutral profile relearn, removed intake, etc) and everything looks good. During test drives the car starts missing at over about 4,500 RPM.

    Right now they are mystified. Y'all have any ideas of what can be going on here???

    Thanks.
     
  2. spartan

    spartan TMO Race

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    I just replaced my Crankshaft positioning sensor after trying several things that checked out. Have they replaced the CPS?

    No more misfire codes.


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  3. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    I don't know. Will check with the shop foreman Tuesday.
    Thanks.
     
  4. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    Quick update. Word from ford is that some heads have some residual sand from the casting that gets into the thermostats and cause them to stick open. Odd, but that is as good an explanation as I've heard.


    They still cannot diagnose the misfires. @spartan they have NOT changed the crank sensor. They want to do only what ford tells them to do. Did your dealer change your sensor? Is there someone at your dealership that my shop foreman or the ford field engineer could talk too?

    Thanks.
     
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  5. spartan

    spartan TMO Race

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    I did all the work myself with help from a forum member. I’m sure they will figure it out. They have all the computers to diagnose the problem.




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  6. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    Thanks. They are working hard. Dealership is in touch with field engineers and hot line.
     
  7. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    Latest update...… They recently changed the crank position sensor and the "tone ring" and the cats. They did the neutral profile relearn. Misfires continue. Shop foreman says the scan tool sees misfires begin at the mid RPM range and after a certain number (100 maybe) the computer pulls fuel from the "misfiring" cylinders and power drops off. He feels no misfires. So the computer thinks there are misfires, but there are not. Sounds a lot like the neutral profile relearn, but they DID do that.
    Any insight from y'all would be appreciated.
     
  8. TMSBOSS

    TMSBOSS TMO Addict

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    I had the same issues. Replaced the clutch and CJ ring. Had to do the relearn twice. After the first time I had limp mode. Not sure this will help with your problem, helped with mine.
     
  9. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    Thanks. I'll pass that along. Relearn is quick and easy. He should be willing to try it again.
     
  10. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    Thanks to all who have made suggestions.

    Another update.
    They now replaced the clutch and flywheel and, of course, did another neutral profile relearn. Drove the car today with the shop foreman monitoring his equipment.
    Driving normally, no problem.
    Hard acceleration, no problem.
    Foot off throttle, car decelerates, no problem.
    Add back a little throttle -- a bunch of misfires detected then computer shuts off fuel to misfiring cylinders.
    Drive normally a while, car is back to normal.
    WHAT THE BLOODY HELL!!!!
    At least this pattern is repeatable -- somewhat. Sometimes only one cylinder "misfires". Then the next time several "misfire" and the one before looks good.

    I would appreciate any suggestions.

    To summarize:
    Neutral profile relearn done many times (up to 6,000 RPM at suggestion of field engineer)
    New crank position sensor.
    New Cats
    New tone ring
    New clutch
    New flywheel
    New spark coils
    New plugs
    Intake has been removed to check runner controls (OK)
     
  11. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    Hmmmmmm. Wiring harness maybe????? It has been unplugged and plugged several times.
     
  12. VoodooBoss

    VoodooBoss Rick Moderator

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    Still having problems?
     
  13. 8250RPM

    8250RPM TMO Addict

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    What are the codes you’re getting?
    Have they done a compression test?
    Have they done an injector balance test?
    Have they checked the injector spray pattern?
    Have they checked the fuel pressure?
    Any modifications done to the car?
    What fuel are you using?


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  14. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    They are getting several misfire codes. Cannot feel any misfires, so I don't think it is actually misfiring. They have done some injector tests but I'm not sure which ones. Always use 93 octane. Very few modifications -- autoblip, caliper studs, pads, wheels, tires, opened up grill at the intake location. Nothing that should affect false misfire detection. Only electrical modification is autoblip.
     
  15. JeffV8

    JeffV8 TMO Race

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    I got misfire code #2+#8 cyl after new flywheel and clutch. Brought back to Ford and they did crank relearn and faults never came back.
     
  16. 302BOB

    302BOB TMO Addict

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    All this new technology with code alerts and alarms scares me. Why does a car have to relearn something when there's nothing wrong?..Old dogs and new tricks...you know the rest...progress is progress...........I guess.......
     
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  17. JeffV8

    JeffV8 TMO Race

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    I think the Exedy Hyper. clutch flywheel is lighter. That could cause the problem
     
  18. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    Clutch and flywheel are stock -- new, but stock. They are stumped by this. Latest plan is to put in a new engine. They are trying really hard.
     
  19. YellowJacketBoss302

    YellowJacketBoss302 TMO Race

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    They have done the relearn many times. I was in the car the last time.
     
  20. VoodooBoss

    VoodooBoss Rick Moderator

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    New engine? Wow that seems extreme. Good luck.
     

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