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

Discussion in 'SN95 4.6L Mustang Tech' started by evolucion311, Aug 18, 2011.

  1. So get this.... the popping over the radio disappears COMPLETELY when the #5 COP plug is pulled off the COP.

    Edit: The yellow ACCEL COP was on #5. When i removed it and put it on cylinder 1 the noise went away. It seems that the Accel yellow cop is noisy.

    Unplugging the capacitor next to #5 with the yellow Accell on it caused the popping to get louder, plugging it back in made it quieter but was still there. Disconnecting COP #5 pigtail made it disappear altogether.

    Unplugging and swapping the capacitors did not have any effect on the engine misfire.
  2. Dude, that is some really bizarre ****. That almost sounds like a HV discharge in the cabin. This sound is coming from the speakers?
  3. sounds to me like you have a open ground in the cop system and its back feeding the radio or the plug wire has a hole in it and it is arch out on the inside of the plug hole down by the plug wire
  4. Trinity, 98kris, please see above post. It only happens when the yellow accel coil is on cylinder 5. I have gotten the sound to stop.

    It is not diacharging inside the cabin... It is so loud because I turned the speakers up full blast. The tick is barely heard over the speakers otherwise.
  5. Anyone want to place bets on it being a bad computer or bad ignition coils?
  6. I ask that because the cruise control no longer works and this morning the car threw a P0118 - coolant temp sensor input

    AND the temp gauge didn't work at all until about 5 minutes into the drive.

    Additionally, the cruise control doesn't work.

    Any bets?
  7. Temperature gauge reading low could be air in the cross over. You can start troubleshooting this by disconnecting the ECT electrical connector. Measure the key on voltage between the LG/RD and GY/RD wires. Should be 5 volts.

    Reconnect the electrical connector and measure the voltage across the ECT. Post.

    Post what the ODB2 sensor says the engine temperature is.

    I hadn't realized these are aftermarket coils until very recently. My vote is the coils. If one or more coils are leaking/arcing/bad grounds, moving to another cylinder is not going to fix the problem.

    P0118 - Engine Coolant Temperature (ECT) Circuit High Input

    Open circuit in harness
    Sensor signal short to power
    Damaged PCM
    Improper harness connection
    Damaged sensor
  8. That or you've got unresolved wiring harness issues.
  9. The only aftermarket coil on the car is the one I picked up to use in troubleshooting. all others are original
  10. Well gents the beast is at the stealership getting a brain transplant. I was able to find an exact match MDE2 / MD2E computer online for $50.

    Let's hope it works!
  11. Absolutely unbelievable. New reprogrammed PCM and it runs just as bad.

    Next? DPFE sensor, coils, or egr valve?
  12. The ECT sensor also doesn't work for the first few minutes of driving. Not low temp, but buried needle all the way to the left not working.
  13. remember for the 99-04 MY Mustang, the dash temperature gauge is actually a signal from the PCM. There are certain "failures" that the PCM responds by commanding the dash temperature gauge to display "hot".

    To diagnose this will need to know what the PCM "thinks" the engine's temperature is. Since you have an ODB2 scanner, this should be easy.

    Also handy to know what the voltage across the ECT sensor is. Disconnect the sensor electrical connector and measure the voltage across the open ECT connector. This is to check for correct VREF voltage. Should be around 5 volts.

    Note, there are several sensors that use VREF voltage and depend upon PCM pin #91 signal return reference (GY/RD). Some of the sensors are MAF, O2, FTP, DPFE, FRP, TPS, ECT, and CMP (cam).

    This brings up an interesting point regarding the chronically high fuel pressure as reported by the PCM. Has the fuel pressure as reported by the PCM ever been cross checked with an external guage?

    Too bad the dealer didn't put your car on the spark analizer while it was at the dealer. This could have answered the question about a noisey COP causing electrical interference.
  14. New COPs are on order and in the mail.

    No, I haven't tested the fuel pressure with an external gauge.

    Edit to add: I didn't let the dealer do anything other than unplug the old computer and plug in the new one and program it.

    I don't trust them and I absolutely will not ever take my car to a dealer for service. The POS service writer looked at the car like a cash machine. Starting telling me how the rear brake pads needed replacing "so we'll go ahead and get that done for you, you can pick it up after lunch."

    Uh, no, mothereffer, you won't.
  15. New COPs didn't help. Ugh.

  16. OBD II Code List

    Are you still getting the random misfire codes? I know this is a on going ever changing issue for you, but the link seems to incorporate several possible issues causing the misfire and other misfire codes. They seem to include the Crank sensor and EGR issues. I haven't been completely following you to see what you have and haven't replaced.

    Good Luck man!
  17. I am getting P0300 (random), P0305, P0307, and P0316 (within first 1000 revolutions).

    My ECT signal is intermittent but doesn't seem to change with doing the wiggle test on the harness at the sensor. I have tried doing ford shop manual pinout tests but am unsure if I am doing them correctly.

    I'm not sure how to diagnose a short to power or a short to ground.

    My computer won't even display the ford wiring diagrams showing where VREF, etc., are routed throughout my car.

    For the sake of brevity I may start another thread dedicated solely to those pinouts.

    So far the only things I haven't replaced have been the EGR valve, the FRPS, the DPFE sensor, and the other black plastic sensor on the other side of the DPFE bracket. I haven't replaced the CMP, either.

    Installing a new ECT sensor did not correct the problem.
  18. Im no expert but I thought maybe I could chime in my thoughts. Not to sure if it'll be any help or not. Been following your thread for a while and been doing some research cuz I had similar issues before the motor was rebuilt in my 96 GT. I dont remember seeing if you checked any of these items so I thought maybe I would suggest them. Figured with how much time you've spent already that it wouldnt hurt to check. From what I have read and asked 3 of my buddies that all do automotive repairs I wonder if your CKP sensor is bad causing the p316. Also i was thinking maybe your EGR valve is bad causeing the misfire? My stang had a misfire way back when on #5 and tried everything finally replaced the EGR and it went away for bout a year(then my whole motor pretty much blew). Also you could check the EVAP emmisions system might have a faulty sensor? Like I said I'm no expert or anything but wanted to try suggesting something different. Maybe it'll help. Good luck. I'd like to see what it is when you finally track it down. I'll keep checking in on this thread.
  19. Diagnois a short to ground by removing the PCM and measuring the resistance between the wire in question and ground. Should be high. If not, this indicates a possible short to ground.

    Diagnois a short to power by reading the resistance beteween the wiring in question and battery positive (key off).

    It's important doing resistance tests there be no stray voltage on the line.

    As for other tests see the following posts this thread:

    Post 173 this thread

    Did the ECT problem start when the new PCM was installed?

    The EGR was mentioned as a possible source. However, excessive EGR flow should present across all cylinders.
  20. The ECT issue started before the PCM was replaced. The ECT shows no signal at engine start up. After a few minutes the ECT will start sending a signal. I have measured 4.6 - 5.0 volts on the ECT harness.

    The CKP has been replaced.

    Replacing the ECT and PCM have not corrected any issues.

    Could someone please provide a wiring diagram of everywhere VREF goes? My understanding is that this wire is responsible for almost all of the engine sensors. If I have a wiring issue and signal is leaking or grounding out, then it seems reasonable that the bad info that is being returned to the engine could be resulting in my misfire while nothing is mechanically wrong with the engine.

    I am asking for the wiring diagram because my Windows 7 copy on my Macbook encounters "script errors" when I try to load the diagrams from my ford repair manual DVD. I think the DVD program was designed to run on an old version of Internet Explorer.