CEL flashing, bad idle, severe misfire, P0302 P0316, compression test results

Discussion in 'SN95 4.6L Mustang Tech' started by evolucion311, Aug 19, 2011.


  1. evolucion311

    evolucion311 Member

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    As requested here is a pic of the front of the crank pulley.

    UPDATE: I installed a new trigger wheel and it is marginally tighter than the old wheel. Maybe it'll help. Maybe I'm just out of $30.

    Pic:

    [​IMG]
  2. hotcobra03

    hotcobra03 Active Member

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    well it sure appears pulley wasnt seated ,,,i was looking for something .20 size silicone is my guess on why it didnt seat fully...was hoping wmburns put hes .02 in...
  3. evolucion311

    evolucion311 Member

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    HotCobra, on what do you base that conclusion that the pulley was not seated properly?
  4. hotcobra03

    hotcobra03 Active Member

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    too much silicone...its all over trigger wheel and back of pulley...


    .20 is is the thickness of a matchbook...when you pressed it on silicone was between pulley and trigger wheel..as time passed silicone was washed away from oil allowing play of trigger wheel..odds of crank pulley moving because pressed fit on crank i cant see that moving ...
  5. hotcobra03

    hotcobra03 Active Member

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    example,,when you install front cover you put silicone dabs in 6 spots..you have 4mins to install cover..if more than 4 mins silicone will harden and cover wont seal,or may leak down the road...
  6. hotcobra03

    hotcobra03 Active Member

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    you might want to put pulley on without front cover and see how tight trigger wheel is
  7. Lugnuts

    Lugnuts Member

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    Make sure that you only use the silicone on the key way - just a dab to prevent leak. Silicone all over the crank snout can limit the balancer's ability to do it's job - that is why the "crank pulley is a two part unit with an elastomer in between is to dampen harmonics and a good solid connection is required to do this.

    I am still not 100% sold on this as the solution though. Do you own or have access to a crank turning tool/nut? I would be curious to see which tooth is for #2 and if the play or potential wobble of the timing wheel were greater in that specific direction. Maybe the timing wheel was cocked on the snout and that tooth fell outside of a solid pickup signal IDK.

    I too think installing the balancer with the timing cover off would be a good idea so you can determine if it is seating all the way.

    If you are worried about gaskets and are fairly certain that you have found the solution - put it back together with the old gaskets and run it to check. Sure you may leak a little but you can pull it back down once you know for sure you have solved it and put the new gaskets on.

    I know this is frustrating but hang in there - it takes longer when trouble shooting remotely but cost is far less.
  8. hotcobra03

    hotcobra03 Active Member

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  9. wmburns

    wmburns SN Certified Technician

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    Based on everything learned so far, to me the best theory so far is the crank damper not fully seated.

    • There is evidence of the trigger wheel contacting the inside of the timing cover.
    • The original pictures of the trigger wheel show anodized coating on the teeth. This is bright and shinny on the later vids.
    • The DTC P0316 supports an unstable CKP sensor.
    • The CKP sensor is new. Replacement did not improve symptom.
    • The trigger wheel is obviously loose on the crank key way. Obvious signs of metal fatigue on the trigger wheel key way.
    • It's well known that an incorrectly torqued crank damper bolt can cause an unstable CKP signal.
    • Reuse of a TTY bolt. Likely resulted in not enough clamping load needed to fully seat the damper.

    IMO, it's very reasonable that a combination of trigger wheel wear, and movement/misalignment of the trigger wheel and CKP sensor could lead to an unstable CKP signal. So I agree that the right course of action is the new trigger wheel and an new crank damper bolt with a correct re-torque.

    I'm personally have a hard time believing that the silcone is responsible for the problems. However, I do recommend to use more silcone on the OUTSIDE between the washer, damper, and crank. Excess silcone will not hurt anything here.

    It goes without saying that any issues with the timing set need to be address now. If there isn't any evidence of excessive wear on the shoes, then replacement isn't needed.

    Part of me still thinks there are other issues going on. But why waste time on conjecture? Put it back together and find out.
  10. evolucion311

    evolucion311 Member

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    I just put the crank pulley on the crankshaft and seated it all the way. The timing wheel was quite snug against the crank and pulley and showed no movement.

    Now I'm off to install the timing cover tonight.
  11. hotcobra03

    hotcobra03 Active Member

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  12. Rick 91GT

    Rick 91GT SN Certified Technician Site Sponsor

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    I am a engine builder and you really should replace the bolt, after a few uses it is stretched a little to far. I recommend the ARP.

    I would try to keep as much silicone off the back of the pulley as possible. Although I do not think that was causing you major issues. Also make sure the key sticks up far enough to get proper engagement in the pillows and gears.
  13. Rick 91GT

    Rick 91GT SN Certified Technician Site Sponsor

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    I have a bolt in stock, or could have one shipped to you if needed. Let me know if I can help...
  14. evolucion311

    evolucion311 Member

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    Thanks for all the support guys, I picked up a new crank bolt from Ford. I used the old crank bolt to start the crank pulley on the shaft and then finished the deed with the new crank, torquing to 67 ft/lbs, backing off one full turn, torquing to 35 ft/lbs, and then another 90* turn. The crank pulley is quite snug to the timing cover and is an equal distance spaced to the cover as is the steering pump pulley.

    I lost, somehow, one of my valve cover grommet plugs and will have to pick up another one from Ford tomorrow before I can start the engine and see if my repairs were successful.

    I will update the thread promptly when I have news, fair or foul, to report.
  15. wmburns

    wmburns SN Certified Technician

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    Consider getting a valve cover gasket set from your local autoparts store. The Felpro set includes all gaskets and a FULL set of grommet plugs. IMO, this is a better deal because this gives NEW valve cover gaskets.

    Besides, Ford is likely to charge as much for one grommet as FelPro charges for the whole set.
  16. evolucion311

    evolucion311 Member

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    Burns, thanks for the reply. I got a FelPro gasket set from AutoZone that included all of the 22 rubber grommets needed. My problem was I lost one of the "male" metal studs that go through the grommets and seat into the valve cover and the valve cover gasket allowing the bolts and studs to seat properly.

    I got one from Ford for $9 today, only needed one. The Ford part includes both the rubber and the metal. I only needed one metal. 6C518 is the part number for posterity.
  17. evolucion311

    evolucion311 Member

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    Well gentlemen, nobody wins the prize.

    The car is put back together and runs just as chitty.

    Next idea?
  18. trinity_gt

    trinity_gt Advanced Member

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    I'm drawn back to the fact that you've got a specific cylinder misfiring and what appear to be abnormally low compression numbers.

    When you did the compression test did you (a) remove all plugs and (b) crank the engine with the throttle pedal at WOT for several full cycles? Was the engine warm or stone cold?

    Can you re-do the compression test to verify the initial results? 100psi sounds really low...
  19. evolucion311

    evolucion311 Member

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    The compression test was done on a warm engine with the throttle plate closed, not open fully.

    I am encouraged by the test results in that they were all fairly uniform, even though low, which may be expected on a motor with 150k miles

    Yes, all plugs were removed during the compression test.
  20. evolucion311

    evolucion311 Member

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    I ran the test twice with no oil and twice with oil in the cylinders.

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