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. MAJOR UPDATE 12/27/11: The car is fixed. I pulled both cylinder heads off, machined them, and reinstalled. I changed the spark plugs from copper core Autolites to platinum core Motorcraft. I am still having an electrical issue with the ECT and a P0118 code but I think this is a wiring problem.

    Lessons learned:
    1.) Don't bother with troubleshooting EFI stuff without a scan tool.
    2.) If one bank of the engine has a problem, do the same treatment on the other bank of the engine, ex: replace sensors, machine heads, etc. It sucks buying gaskets twice.
    3.) Using YouTube can get you a long way in explaining your problem, especially if you aren't a "car guy."
    4.) Call several machine shops/dealers and start a price bidding war for services. A Ford dealer wanted $300 to reprogram my PCM. I laughed in his face and left. I got my PCM reprogrammed for $95 by hustling the dealers and bidding them down against each other. Little business is better than no business.
    5.) SYNTHETIC OIL IS WORTH EVERY PENNY. I ran Mobil 1 5w20 or 5w30 religiously since day one in the car and when I pulled the heads apart the cam lobes were so clean you could eat off of them.. Absolutely no visible wear at all, just mirror smooth surfaces..... at 154,000 miles and lots of city stop and go miles.
    6.) When the CEL flashes at you, you have a serious, serious problem. $100 for a tow to a reputable shop will save your ass. Don't push your engine when the PCM is sounding a three bell alarm. Immediately stop your vehicle and shut it off. In the case of losing oil pressure, you have a matter of seconds before your engine is toast.
    7.) When pulling heads off the engine, drain the heads and block by removing the drain plugs on each. Even though I thought my engine was fully drained of coolant, it was not. When the heads came off the coolant got into the oil pan and I used about 4 gallons of oil flushing the thing out to remove all the water. An ounce of prevention is worth a pound of cure.
    8.) Get a proper Ford DVD service manual.
    9.) WMBurns, 1987Stangman, trinity_gt, Rick91GT, and HotCobra03, are the man!

    CASH REWARD - CEL flashing, severe misfire, P0302 P0316, compression test results

    I will leave this unedited for posterity... my frustration was unfairly directed toward those that were trying to give me advice at the expense of their own time. Having StangNet as a resource makes a project like this actually possible! Thanks guys and my apologies.
    Edit: 10/17/11 - THE CAR IS STILL RUNNING LIKE CHIT. THRU THE NEXT 8 PAGES YOU WILL READ OF HOW INTERNET ADVICE DOESNT END UP DOING A DAMNED THING. Through pulling a cylinder head off and doing a valve job to trying endless hours of pinout tests with a Ford repair manual I am STILL unable to fix this god damned thing. I give up. I will update this thread when the car is actually fixed, but as of now consider this entire thread a complete waste of my time. I tried to create a record of this so that someone else could use it as a resource in the future. Turns out it was all a big circle jerk.

    EDIT: 9/13/11 - After valve job on passenger side head throwing original P0302 / P0316 code and verifying bad valve, put good head back on. Computer is throwing P0305 / P0316 now.

    Cliff Notes for the next 4 pages: bad misfire, tried all the usual stuff to remedy, ended up being a bad #2 cylinder exhaust valve.... to be confirmed as soon as I get the head pulled off tomorrow (Saturday)


    Gentlemen of StangNet: I have a problem that I request your help with. I have contributed to this forum by making a YouTube video on swapping an ABS module w/o removing the brake lines.

    I cruised the forums and searched trying to cure my ills before making this post and I will update the community throughout the ordeal and will actually update the final resolution... something I wish more people would do!

    My 2002 GT has 153,000 miles on it and I was driving down the road at freeway cruising speed when the car lost power, started shuddering and shaking when given throttle, and a few moments later the CEL light illuminated and later started flashing.

    I pulled the codes and got P0302 and P0316 which are Cylinder #2 misfire and Misfire detected first 1000 revolutions on start up.

    I should also mention that for two days before this point the vehicle was making a slight ticking noise that followed RPMs and sounded like an exhaust leak. It turned out to be the #2 cylinder spark plug was loose but there is no thread damage. PLEASE NOTE THIS POINT: The spark plug was grey with carbon as was the spark plug well from the compression blow by. All other cylinders' spark plugs were normal and tight.

    The car runs like a scalded dog, particularly under load and the idle is rough, the exhaust note is notably different. Sounds like an old dump truck, glarg glarg glarg.

    What I have done up to this point following common sense and an order of repair....

    1.) Replaced all plugs and plug boots.
    2.) Replaced #2 cylinder with a new coil on plug (COP)
    3.) Removed all fuel injectors, cleaned them, and replaced them. I swapped #2 injector with the #6 injector on the opposite side of the engine to see if an injector code would follow it. It did not. I'll get to that in a second...
    4.) Cleaned MAF
    5.) Replaced fuel filter.
    6.) Replaced serpentine belt.
    7.) Tested for DC voltage on fuel injector harnesses, all test at about 13-14 volts
    8.) Tested impedance (ohms) of all fuel injectors. All tested at 15.6 ohm.
    9.) Tested for voltage on plug wire pigtail connectors. All pulsed around on the multimeter and had power.
    10.) Replaced crankshaft position sensor (CKP)
    11.) Tested the alternator for AC voltage between the red post and housing with a .6 volt result.
    12.) Tested the alternator for DC output with a 13.3-13.6 volt result. Please note I have a new battery and that the car has had Steeda UDPs for 40,000 miles with zero issues.
    13.) Performed a compression test with the following results:

    Initial Test on Cylinders:
    1 - 105 5 - 115
    2 - 100 6 - 110
    3 - 105 7 - 105
    4 - 100 8 - 110

    Second test with a capful of oil in the cylinders:
    1 - 140 5 - 160
    2 - 135 6 - 150
    3 - 140 7 - 135
    4 - 135 8 - 160

    *** I used a small amount of oil on this test but did not exactly measure how much I was using. I deduce from this second test that the valves are NOT an issue which is a relief considering that a burned exhaust valve or bad seal was a big concern to me as being the cause of this problem. EDIT 8/28/11: IT WAS A BAD VALVE AFTER ALL, HAD TO DO A LEAK DOWN TEST TO CONFIRM

    The #2 cylinder spark plug was replaced with a new Autolite 764 which was also the previous model. The last plugs were in the car for about 50,000 miles. Torquing the plugs in did not remedy the problem. The plugs were checked after a drive and were still tight. No thread damage is apparent.

    After all of the above actions the car still runs pretty badly at idle, in traffic at low rpms and under load BUT after about 2,000 rpm the misfire and shaking subsides and the engine will roar to life with power though will still have a bit of a hiccup under load at higher RPMs. There is a distinct difference between idle/low rpm and high rpms here in terms of drivability and performance. The CEL light came back with the same codes, P0302 and P0316 even after a new coil, plug, boot, and swapping the injector.

    HELP! :shrug: I'm at my wits end here. The compression test results are a bit encouraging that I don't think I'll have to tear into my heads to repair a valve. The car's motor oil is clean and fresh. The car does not smoke at all. Oil consumption is about a quart over 3-5,000 miles... not bad for a 150k motor.
  2. A couple of things occur to me. The AC ripple seems high. I have no idea what the official limit is, but 0.6 volts is 5%. Seems high. Recommend having the alternator tested with an official tester.

    The un-oiled compression seems a little low. However, I don't think this is the source of the problem.

    What has been done to rule out a vacuum leak?

    Do you have a vaccum gauge? How's the manifold vacuum?

    What has been done to rule out excessive EGR flow? Inspect the vacuum lines to/from the DPFE sensor. If the EGR vacuum line is disconnected and plugged, does this improve the symptom?

    Does the motor make a rattling noise during start-up? How long does it last? Get yourself a mechanic's stethoscope. Listen around the timing chains for noise. Not a bad idea to cut the oil filter open and inspect for small bits of metal just to be sure.

    What has been done to rule out a blocked cat?

    Very good post. Well organized. Complete.
  3. I agree with wmburns: Great post. Your diagnostics have been very thorough and don't leave a lot on the table. A thought or two:

    If the misfire is persistent on #2 despite changing the plug and COP and the cylinder is mechanically sound and getting fuel then the problem lies upstream of these parts. I'd start by tracing the wiring harness back as far as you can. Look for pinch-points and areas where chafing has occurred and for areas where wiring has been damaged. The likely areas will be in the tightest, hardest-to-get-at vicinities so be patient.

    If no wiring faults are found you might have a problem in the PCM itself. The ignition driver, for example, may have a bad solder joint or there may be cracks in traces, corrosion, bad components (e.g. tantalum capacitors can pop, the electrolyte in aluminum electrolytics can dry out or they can heat up and burst; this can be especially prevalent if the AC ripple in the system is high...) etc.

    I agree too that the pre-oil compression numbers look quite low. However, compression values are very dependent on things like cranking speed, whether the throttle was wide-open or not, engine temperature etc. The fact that all are reasonably close means that while there may be ring or cylinder wall wear, the engine appears to be in generally decent shape.
  4. I was exploring in my mind the idea that it could be fuel related because I was able to observe a spark from the coil and plug when cranking over the engine with the fuel disabled and the plug out of the engine (the only one connected).

    I tested the voltage at the fuel pump driver module connector (FPDM) and got a 12v reading at the connection harness after following the workshop repair procedure indicating that any value above 10.5 is unacceptable and indicates a bad FPDM that should be replaced.

    Is this a reasonable idea to explore?
  5. WmBurns, I have sprayed around piping and gasket borders with carb/throttle body cleaner in an attempt to make a vacuum leak apparent. I will not discount this idea and will perform the procedure again. Perhaps I missed something.
  6. Allow me to answer a question with a question.

    What is the fuel pressure? By you own post, it runs like a scalded dog. What's your theory on how the FPDM module causes the symptom?

    In my experience the FPDM either works or it doesn't. It makes more sense to be a fuel pressure sensor problem. For example, something wrong with the fuel pressure intake vacuum reference line.

    Consider if the FP reference line were disconnected/leaking then the Delta fuel pressure would go high at idle. The delta FP would drop as the intake vacuum decreased. This would create a rich condition at idle that would would decrease as RPM's goes up.

    That would offer an explaination why the idle is so poor where as it runs better at higher RPM's.

    So... this can be ruled in/out by measuring the fuel pressure. Check the intake vacuum reference line for leaks or raw gas. Another method is to compare the LTFT's at idle and load.

    IMO, the misfire on #2 doesn't fit the fuel pressure theory. However, what if there are two issues?

    IMO, don't focus on the FPDM until all other causes have been ruled out.
  7. Very good post from all involved. This is quite the mystery.

    If it were a vacuum leak, would the code not wander from cylinder to cylinder? Carbon build up on the EGR can cause a misfire too but I am still wondering why it persistently stays on cylinder #2 even after injector relocation and verification of spark.

    If the engine was running rich, there was no indication from the description of the spark plug description.
    If you disconnect the ignition to the #2 cylinder at idle does it get worse or stay the same?
    Do you have access to higher end tools? A digital storage oscilloscope would show you the firing voltages of each cylinder - I would like to see if peak firing voltage is consistent across the cylinders. Then throttle the engine and let it fall back while watching the pattern on the scope. All firing voltages should increase the same.

    Another thought, intake gasket leak on #2? Add the base of the intake to your vacuum leak inspection.

    If you make the air/fuel mixture lean by pulling off a vacuum hose you should see a change in the injector pulse width as the computer responds to the O2 sensor - if not, suspect computer problem.

    Do you have access to a data logger/tuner? These really are helpful tools.

    I am curious to see how this is resolved.
  8. It seems as though he has checked almost all issues including the Crank sensor. But would a bad camshaft position sensor have the same effect?

    I still remember having a bad alternator will cause severe electrical gremlins as the car's battery is strong enough to start the vehicle but does not have enough to adequately power the car as it is running in the lower RPMS when it is struggling to recharge the battery. Next cheap step would maybe borrow another battery from a friend or have the alternator tested on a true machine (if you only used a multi-meter or whatever.
  9. update: I took the alternator off and had it bench tested at two different auto parts stores. Both tests were good. I specifically asked about the diodes. The manager had marginally more intelligence than the counter monkey that looks like she was hired two weeks ago. Two machines indicate that the alternator is good.

    I just called the junkyard and they have a PCM for $100. I'm debating whether to give that a try. Will I have PATS issues if I swap them out using the correct Ford part numbers?

    I retested for a vacuum leak with more carb cleaner without success.
  10. @ Lugnuts:

    Disconnecting the #2 cylinder fuel injector and/or spark plug COP connections has no effect on the running of the engine. The cylinder seems to be dead. I have verified that the cylinder is getting spark. It may not be getting fuel, leading me to believe the PCM could be bad as previous posters have suggested.
  11. Have you confirmed a firing pulse with a "noid" style tester?

    If no firing pulse, the problem could be in the device, in the wiring, or in the PCM.

    The device is usually ruled out by swaping to another cylinder.

    An option for bad fuel injectors is a cleaning/flow test service such as injectorrx.com.

    The wiring is usually ruled out by "ringing out" the signal return wire with an Ohm meter. For the SOHC motor, the fuel injector return wire is WH to PCM pin #101. Test for ground fault as well.

    The PCM is usually declared bad after everything else has been ruled out. Couldn't hurt to inspect the PCM PC board. Sometimes there's is obvious damage (burned parts).
  12. Update: Looks like we can rule out AC ripple from the alternator. I purchased a new alternator, installed it, and the problem was there again. The parts counter guy was cool and will let me return the alternator tonight (even though installed for all of 30 seconds).

    Another update relating to EGR: I removed the EGR valve and plugged the hole into the intake plenum. I then started the car. It still ran like ****.

    WMBurns, I do not have a solenoid tester to confirm a pulse. I assume you mean to test the signal coming from the PCM to the #2 injector over the pigtail plug? Is a noid tester required... could I measure the pulse on my multimeter?

    Thank you for your help gentlemen.
  13. Update: I removed the PCM examined the circuit board. I was unable to see any obvious signs of damage.
  14. Update: I tested the impedance (resistance) between the pigtail for fuel injector #2 (white wire) and pin 101 (white wire) at the PCM harness. I got a reading of 0.0 and then 0.2 ohms.

    I then tested injector #4 pigtail (brown w/ light blue stripe) and pin 100 at the harness (brown w/ light blue) and got the same zero to 0.2 ohm result.

    Does this indicate that the wiring is in good shape?
  15. For the EGR test remove the vacuum line to the EGR valve. Not the EGR line itself!

    A "noid" tester is really just a fancy test light. They can be rented from the local parts store. Harbor Freight also sells an affordable set.

    Amazon.com: Wilmar W85103 Ford Tbi F/Inj Test(Noid)Light: Automotive

    The wiring test should include a test from the wire to ground. This is a ground fault test. The Ohm value should be high indicating an open circuit.

    On your video, it seems to me that you are very close to lugging the motor. Anytime a motor is run under 1500 RPM's you can't just pour the power to it. In a low RPM high load configuration, add power slowly. This preserves the motor's vacuum.

    It's also possible that the motor's low compression is playing a part in this Greek tragedy.

    What is the fuel pressure? A tester can rented. I still have doubts this is a fuel pressure issue because it only affects one cylinder.

    FWIIW, an ODB2 scanner is likely to make short work of this. Or at the very least, save a bunch of time.

    Consider an injector cleaning and flow test service such as injectorrx.com. I have had great results with their service. Once cleaned, they are as good as new and cheaper than new.
  16. I removed the EGR vacuum line from the top of the "UFO" with no result.

    I have gone through two cans of throttle body cleaner trying to find a vacuum leak. I have not been successful.

    I disconnected the MAF and made the following video.... disconnecting the MAF made the car stutter for a second and then it went into open loop mode and still ran the same degree of ****ty.

    BUT.... it is making a noise from the front of the passenger side cylinder. Check out this video.... any ideas? Bad - YouTube
  17. So here's a video of a readout of what a scan tool measured for the fuel trims, fuel pressure, etc....

  18. Are you positive that all spark plugs have been correctly torqued?

    To me, I hear the timing chains rattle. Get yourself a mechanic's stethoscope and probe around the front timing chains.

    Consider taking the valve covers off. Inspect the timing chain tension adjusters. This will also offer a good chance to inspect the cams and roller followers.
  19. That intermittent stuttering noise I identify in the video turned out to be the IAC cycling.