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. wmburns

    wmburns SN Certified Technician

    Joined:
    Aug 14, 2009
    Messages:
    3,170
    Likes Received:
    58
    Trophy Points:
    69
    Location:
    Houston Texas
    The VREF sensors are ECT, FRP, TPS, and DPFE.

    VREF signal return is PCM pin 91. Obviously a problem in the return wire could affect the reference voltage as well.

    You are correct. The older versions of the Ford Service DVD will not run on today's PC's. Java and IE differences. The later versions will run fine (I use them everyday to answer posts).
     
    #181
  2. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    So when I attempt to run pinout test DA13 this is what I get: dropping resistance on the VREF / SIGRTN lines as sensor connectors are plugged back in.

    Wutcha think guys?

    WATCH ME PLEASE!
     
    #182
  3. wmburns

    wmburns SN Certified Technician

    Joined:
    Aug 14, 2009
    Messages:
    3,170
    Likes Received:
    58
    Trophy Points:
    69
    Location:
    Houston Texas
    You are not doing test DA13 correctly. The resistance test should be between VREF(90) and the sensor return. For the ECT, that is PCM pin #38. For the FRPS it is PCM #63.

    When measuring between PCM pin 90 and 91, you are reading the resistance of all of the sensors. The drop in resistance is to be expected as each sensor is re-connected.

    You do understand that the pin point tests MUST be done in order. The tests are designed in such a way that each test depends upon the results of the preceeding steps.
     
    #183
  4. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    Alright.... so the engine wiring harness is disconnected inside the engine bay to/from the PCM.

    My 5700 ohm resistance is still present with the wiring harness disconnected from the engine.

    See video 2: HERE WATCH ME !!!!
     
    #184
  5. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    Burns, I started at the beginning of the test series and went step by step to the point I am now at.

    I just re-ran DA13 by using pin 90 BN/WH and pin 38 LG/RD and get infinite resistance. (after restoring all harness and connector fittings to their connected position)

    DA13 between 90 BN/WH and pin 63 RD/PK gets 22,800 ohms.
     
    #185
  6. wmburns

    wmburns SN Certified Technician

    Joined:
    Aug 14, 2009
    Messages:
    3,170
    Likes Received:
    58
    Trophy Points:
    69
    Location:
    Houston Texas
    If you are going to go "off resveration" and you expect someone to follow you, it sure would be nice if you left more bread crumbs along the way.

    For example, WHICH connector are you testing between the pins and why?

    I ask this because my wiring diagrams indicate that the ECT sensor goes through C104 and C294 ONLY. C104 is the large square main engine harness connector. C294 is the main PCM connector.

    I don't have a clue which connector the smaller one near the PCM is or which pins are being tested.

    Also, have you "zeroed" the mult-meter? Are the batteries fresh?

    These tests are complicated enough that each tests needs to be documented as:

    Tested between connector Cx1 pin #x2 to connector Cz1 pin #z2. The results were yyy Ohms.

    Any mistake here is likely to lead to the "wild goose chase" from hell.
     
    #186
  7. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    DA12
    Measure resistance of sensor signal circuit between PCM harness connector pin and applicable sensor harness connector. green/red @ PCM to ECT - 0.4 ohms

    Measure resistance of SIG RTN circuit between PCM harness connector pin and applicable sensor harness connector. GRAY/RED @ PCM to ECT - 0.5 ohms

    DA12 results - Are both readings less than 5.0 ohms? YES - Replace PCM.

    Durrr I've already replaced the PCM


    DA13
    Key off.
    Disconnect PCM.
    Measure resistance between ***applicable*** temperature sensor signal and VREF circuits at the PCM harness connector.

    Applicable:
    For ECT - pin 38 @ PCM green/red
    VREF - pin 90 @ PCM brown/white
    SIG RTN - pin 91 @ PCM gray/red


    results with all sensor connectors connected to their respective sensors:
    @ PCM pin 38 (ECT) & pin 90 (VREF) - infinite resistance
    @ PCM pin 91 (SIG RTN) & pin 90 (VREF) - .264 kOhms
    @ PCM pin 63 (FRPS) @ pin 90 (VREF) - 22.8 kOhms

    results with all (except fuel tank pressure sensor) disconnected
    @ PCM pin 38 & pin 90 - infinite resistance
    @ PCM pin 91 & pin 90 - 5.86 kohms
    @ PCM pin 63 & pin 90 - infinite resistance

    is resistance greater than 10,000 ohms? well, I'm not sure.

    DA20 - not applicable - sensor already replaced

    DA21 - is voltage between 4.0 - 6.0 volts? YES - perfect 5.0 volts GO TO DA22

    DA22 - Disconnect PCM.
    Measure resistance between sensor signal and SIG RTN circuits and then between sensor signal and PWR GND circuits at the PCM harness connector.

    @ PCM SIG RTN pin 91 & @ PCM ECT sensor signal pin 38 - infinte
    @ PCM SIG RTN pin 91 & @ PCM FRPS sensor signal 63 - infinte

    @ PCM PWR GND pins 3, 24, 76, and 103 (I don't know which pin is PWR GND but simply tested all black/white wires) and ECT signal pin 38. All infinite resistance.

    Is each resistance greater than 10,000 ohms? YES - Replace PCM.

    Durr, again, already done this. No effect.

    So now I'm at DA90 because I have P0118. I don't have a scan tool that can read PID's... I have been borrowing the one from AutoZone
     
    #187
  8. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    So my ECT sometimes sends a signal to the engine KOEO but dies KOER.

    What the fudge?

    Check out the video HERE
     
    #188
  9. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    I replaced the EGR last night. No effect.
     
    #189
  10. hotcobra03

    hotcobra03 Active Member

    Joined:
    Nov 30, 1999
    Messages:
    1,000
    Likes Received:
    1
    Trophy Points:
    39
    Location:
    poteet,tx
    been following and wonder why you havent removed the engine harness from car and check it by un wrapping it...

    it appears you are going in circles..and your codes prove it...

    when you did the head work,did you just push wire harness and vaccum harness to the side and worked with a mess,,or did you pull them from car to make work easy?

    when i read over your testing something doesnt sound right,,than some of your questions make me feel your still confused about things on the engine..

    i had an issuse with my cobra,,the vaccum hose on the egr tube blew off causing a baby exhaust leak.

    knowing how easy stuff breaks i removed 40% off the stuff near the tube to be able to work without added damage..last winter i just lightly bumped the egr vaccum hose while wiping the blower and it snapped....

    with the new coils did the popping sound in speakers go away?
     
    #190
  11. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    Popping sound remains with new coils
     
    #191
  12. 1987stangman

    1987stangman Member

    Joined:
    Jul 13, 2006
    Messages:
    584
    Likes Received:
    10
    Trophy Points:
    19
    I agree with this. It has got the the point that you have gone over just about every thing on this car.

    Another thing I was thinking about was the intake. We all know it's plastic and one thing I did when I was trying to chase down my issue was pull it off and check it really good for any cracks in the runners that might be enough to cause a vac leak. I would either pull the old engine harness and break it down and inspect it or try and buy a stock replacement. At this point you don't have much to loose.
     
    #192
  13. trinity_gt

    trinity_gt Advanced Member

    Joined:
    Jan 31, 2003
    Messages:
    3,048
    Likes Received:
    68
    Trophy Points:
    69
    Location:
    Canada
    No offense evo but while I understand the frustration, this is pretty rude. It's not like the people offering suggestions actually owe you anything. It's your car in your garage: What do you expect us to do from 3000 miles away other than offer suggestions and advice?

    I suggested in post #3 that you probably have a wiring harness problem. I'm sorry you've only just recently -- two months later -- gotten around to actually doing detailed checks of the harness. It may well be that the harness will have to come out to be properly chec-- oh, wait, I'm offering "internet advice"... Never mind.

    Good luck. I suspect those that have been kind enough to take the time to offer suggestions and advice will walk away from this thread after being basically insulted like this.
     
    #193
  14. trinity_gt

    trinity_gt Advanced Member

    Joined:
    Jan 31, 2003
    Messages:
    3,048
    Likes Received:
    68
    Trophy Points:
    69
    Location:
    Canada
    Double post...
     
    #194
  15. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    I have retained a Ford senior master technician to make a house call tonight. I might have to tow the car to his home city for work.

    Thankfully, he's a client and works on the cheap.
     
    #195
  16. hotcobra03

    hotcobra03 Active Member

    Joined:
    Nov 30, 1999
    Messages:
    1,000
    Likes Received:
    1
    Trophy Points:
    39
    Location:
    poteet,tx
    WHAT DID HE SAY AFTER LOOKING AT IT ?
     
    #196
  17. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    That my autolite 764s were the wrong plugs, that I should be using AP764s or Motorcraft SP493s.

    Very little spark visible with new or old coils thru current plugs.

    Highly probable other head needs valve job.

    Electrical issues possibly from lack of grounding from bad plugs.
     
    #197
  18. hotcobra03

    hotcobra03 Active Member

    Joined:
    Nov 30, 1999
    Messages:
    1,000
    Likes Received:
    1
    Trophy Points:
    39
    Location:
    poteet,tx


    so he didnt check your engine harness for you....

    if it were me i would unhook harness in engine bay...unplug connector on coil and test the return circuit for continuity,,,than if it did check ok i would leave 1 probe at coil connector and probe all the other pins in that connector...i should only get a reading on 1 circuit...than repeat for all other circuits in the same manner...

    i thought i posted u 2 links way back...

    1 for chiltons library...in there you will find a pin layout of pcm with pin numbers/discription of the pin number and the voltage value of each pin ...

    Gale Cengage Product Failure

    2) was for how to track down a short

    Automotive Circuit Testing - Help With Check Engine Light Diagnosis
     
    #198
  19. evolucion311

    evolucion311 Member

    Joined:
    Mar 19, 2009
    Messages:
    238
    Likes Received:
    2
    Trophy Points:
    18
    I'm pulling the head for a valve job and replacing the plugs again.

    If doesn't work I am towing the car to him for electrical work.

    I'm done with this ****ing car.
     
    #199
  20. hotcobra03

    hotcobra03 Active Member

    Joined:
    Nov 30, 1999
    Messages:
    1,000
    Likes Received:
    1
    Trophy Points:
    39
    Location:
    poteet,tx
    well thats alot of work again...why dont you pull engine harness on driverside and throw it to the side as your going to do....than plug it back in and see if codes change....what do you have to lose?
     
    #200

Share This Page