Ok guys this one has me stumped. Over the summer my 03 Aviator start throw codes for misfires (mostly random misfire). I have gone threw this issue with Ford COP I ordered 8 new Accel Coils. Issue was still present, codes P0300, P0316. The truck was low on power also, after weeks of data logging I discovered fuel pressure was low. I changed the fuel filter with no change. What I found strange is it wasn't throwing a code for low fuel pressure, hmmm. Fuel pressure was confirmed with a mechanical gauge.
My mechanic thought it was the fuel pump, but I had my doubts since the fuel pump duty cycle was low and the pressure was also low. So I started to think a misreporting fuel pressure sensor (on the rail) was the culprit. The morning that I was ready to get the sensor changed the truck started running normal again, I changed the sensor anyway. Now 3-4 months later it's starting to do it again, although not as bad.
Any ideas?
Lincoln Aviator Issue
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Ghost? Only Kidding.
Next time this happens do the tap test tap the ecm with your hand fairly hard but not so hard that you will break it and see if anything changes also look for a coroded terminal on the ecm
check compression. We see tons of burned exhaust valve guides on these as well as the 03-04 Cobras and Mach 1's and occasionally a Marauder that uses the same heads. Actually have the heads off an Aviator in our shop now with burned valve guides for rough running waiting approval.
Cardinal might be right about this one.
FORD:
2003-2004 Mustang, MustangLINCOLN:
1999-2004 Navigator
2002-2003 Blackwood
2003-2005 AviatorMERCURY:
2003-2004 Marauder
ISSUE:
Some 1999-2004 Navigator, 2002-2003 Blackwood, 2003-2005 Aviator, 2003-2004 Marauder and 2003-2004 Mustang vehicles built before 12/19/2004 equipped with 4.6L 4V/5.4 4V engine may exhibit a runs rough, lacks power, and engine misfire, prompted by a MIL light and DTC codes P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, and P0316.
ACTION:
Diagnose engine for engine misfire concern. If diagnostics determine an engine misfire which is characterized by leakage through exhaust valve(s), only replace the affected cylinder head(s).
SERVICE PROCEDURE
FOR VEHICLES WITH RUNS ROUGH/MISFIRE CONDITION:
Perform relative compression check on all cylinders. If abnormal, check cylinder leakage and actual compression for "low" cylinders refer to Workshop Manual (WSM), Section 303-00.
If leakage/compression check indicates a valve train concern, per valve train diagnostics in WSM, Section 303-00, replace cylinder head and cam assembly, pipe plugs and timing chain tensioner, per procedure outlined in WSM, Section 303-01.
If cylinder leakage and compression tests are inconclusive, perform misfire diagnostic, per TSB 05-22-8.
NOTE:DO NOT TRANSFER SPARK PLUGS. INSTALL NEW SPARK PLUGS IN REPLACEMENT CYLINDER HEAD AND CAM ASSEMBLY.
NOTE:THE ENGINE MISFIRE CONCERN IS TYPICALLY EXHIBITED ON THE LEFT HAND CYLINDER HEAD AND RARELY ON THE RIGHT HAND CYLINDER HEAD. UNLESS CONFIRMED, THE RIGHT HAND CYLINDER HEAD SHOULD NOT BE REPLACED AS AN "EXTRA MEASURE" SERVICE PRECAUTION.
NOTE:THE REPLACEMENT CYLINDER HEAD WILL NOT IMPROVE OR REDUCE ENGINE HORSEPOWER OR TORQUE ABOVE ADVERTISED LEVELS.
PART NUMBERPART NAMEYL7Z-6049-EACyl Head Assy LH (5.4L)2C5Z-6049-BABCyl Head Assy LH (4.6L)YL7Z-6049-FACyl Head Assy RH (5.4L)2C5Z-6049-CABCyl Head Assy RH (4.6L)
For what its worth we usually end up putting in a reman motor in these. Replacing the heads vs. a reman motor is a few hundred dollars price difference and you get a 3 year unlimited mile warranty on the engine instead of 12mo/12k mile with the heads alone.
bcardinal,
Compression and leak down was done a few months ago when problem 1st started and came back fine, then fuel pressure was a low but with no code regarding fuel pressure (only misfire). Then the problem went away for a few months and now returned again although not as bad as last time.
To me that eliminates anything mechanical since the problem went away on it's own. I was sure it was a fuel pressure sensor mis-reporting the pressure, but that was changed and now the problem is back.
What is wrong with these cylinder heads? Do the valve seats recede prematurely or something?
If you had a fuel pressure problem, especially enough to cause a missfire, it seems you would be getting other codes to go with those missfire codes, ie. lean or rich. What are your long/short trims when the problem occurs?
Unless you have a base mechanical concern,and often when you do, there will usually be a PID that will point you in the right direction.
Was a relative compression and powerbalance test run on it when the problem was evident?
It misfires mainly under high load or RPM. When it does it's hard to say because the misfires screw up the trims otherwise the trims look ok.
No other codes other than the P0300 and occasional P0316.
Only compression and leakdown tests. If it were a mechanical issue the problem it wouldn't go away on it's own and resurface 3-4 months later?
Originally Posted By: punisher
If you had a fuel pressure problem, especially enough to cause a missfire, it seems you would be getting other codes to go with those missfire codes, ie. lean or rich. What are your long/short trims when the problem occurs?
Unless you have a base mechanical concern,and often when you do, there will usually be a PID that will point you in the right direction.
Was a relative compression and powerbalance test run on it when the problem was evident?
Originally Posted By: punisher
Was a relative compression and powerbalance test run on it when the problem was evident?
This may have been done by my mechanic, I don't recall at the moment. Assuming these tests didn't point to a cylinder problem combined with the low fuel pressure, what do you think. Could a fuel pump provide intermittent pressure?
Things done so far: All 8 coils and plugs replaced, crank sensor, and fuel rail pressure sensor.
We changed the crank sensor since the p0316 could have been a possible cause and seemed most likely.
If possible have these done when the problem is evident. They can be done without opening the hood on a Ford vehicle.
Originally Posted By: bdcardinal
Originally Posted By: punisher
Was a relative compression and powerbalance test run on it when the problem was evident?
Do you know what the fuel pressure was when it was tested?
I was trying to get over in my first post that a low fuel pressure problem will cause other codes, specifically lean codes. Granted a missfire causes lean codes to (someone on here will argue this with me I bet) but you can ck your CAT temps with an IR thermometer to catch that. Missfires= really hot cat(s). Lean running will lead to lower cat temps.
Something to keep in mind- when dealing with codes and PIDS, you are getting data that the PCM sees, not necessarily what is actually happening. Just because you see low fuel pressure on a monitor, doesn't mean you have low fuel pressure, it has to be manually confirmed with a gauge. Wiring issues are another concern. I have had wiring concerns on Navigators/Contour/Mystiques, oh heck, every Ford vehicle out there, give me headaches. I have had non grounded shielding on cam sensor wires cause erronious CPS readings as well. Essentially, keep an open mind. You might even have some sort of intermittent injector harness concern.
Anyways, with a P0300 you are concerned with a problem that effects ALL cylinders. Which is why I question replacing coils. With a P0300, if I was concerned with ignition, I would be looking at what commonalities there were, harness, connectors etc that when it fails, causes missfires all around. I would want to monitor fuel pressure (to the point of driving around with a fuel pressure gauge taped to the base of the windshield) to catch a concern. Been there.
CKP concerns. A longshot, but FoMoCo did have problems at one time with the CKP connectors on modular engines. I would regularly dissassemble the connector and solder the wires to the female leads.
Very good info. Fuel pressure was varying when tested, sometime low 40's other times about 50. Drive-ability was worse when the pressure was lower. IIRC the pressure should be 50-55 psi. I know return-less fuel systems are more sensitive to pressure than others.
I totally agree about pids and codes being deceiving, I've dealt with this may times before as I have been wrenching on my own cars for well over 20 years.
The reason coils were replaced is I had an issue (misfires) 5 years ago with Ford COP and while under warranty it kept going back to the dealer. This time while this issue was going on I occasionally was getting a P0305 or P306 so I opted to eliminate the coils and replaced the plugs (Motorcraft) while I was at it.
I would suspect the fuel pump but last time the issue went away on it's own for a few months and now it's back again and the fuel pressure sensor was replaced. Could a pump produce good pressure one day and low another? I've never seen that. I swapped out the fuel pump relay from another circuit with no change. Pump was confirmed to be receiving 12 volts.
Originally Posted By: punisher
I was trying to get over in my first post that a low fuel pressure problem will cause other codes, specifically lean codes. Granted a missfire causes lean codes to (someone on here will argue this with me I bet) but you can ck your CAT temps with an IR thermometer to catch that. Missfires= really hot cat(s). Lean running will lead to lower cat temps.
Something to keep in mind- when dealing with codes and PIDS, you are getting data that the PCM sees, not necessarily what is actually happening. Just because you see low fuel pressure on a monitor, doesn't mean you have low fuel pressure, it has to be manually confirmed with a gauge. Wiring issues are another concern. I have had wiring concerns on Navigators/Contour/Mystiques, oh heck, every Ford vehicle out there, give me headaches. I have had non grounded shielding on cam sensor wires cause erronious CPS readings as well. Essentially, keep an open mind. You might even have some sort of intermittent injector harness concern.
Anyways, with a P0300 you are concerned with a problem that effects ALL cylinders. Which is why I question replacing coils. With a P0300, if I was concerned with ignition, I would be looking at what commonalities there were, harness, connectors etc that when it fails, causes missfires all around. I would want to monitor fuel pressure (to the point of driving around with a fuel pressure gauge taped to the base of the windshield) to catch a concern. Been there.
CKP concerns. A longshot, but FoMoCo did have problems at one time with the CKP connectors on modular engines. I would regularly dissassemble the connector and solder the wires to the female leads.
Quote:
sometime low 40's other times about 50. Drive-ability was worse when the pressure was lower
The Aviator fuel system is return-less, to my knowledge the fuel pressure is commanded by the fuel pressure sensor on the rail (it does have a vacuum line) which changes the pump voltage/duty cycle.
It sounds like it could be a bad pressure regulator. Does yours have a vacuum hose going to it on the fuel rail?
Originally Posted By: Trav
Quote:
sometime low 40's other times about 50. Drive-ability was worse when the pressure was lower
Have you checked the pressure with the vacuum line off?
I remember you said you changed that part but it wouldn't be the first time a new part was a dud.
No saying thats the case here but its happened to me a few times, the original was bad and replaced but the problem continued only to find out the new part is defective also.
The new part should be viewed with suspicion. It's new.
Diagnosis is the key, it seems reasonable but I know little about that platform's tricks.
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