jwdaniels

Hey guys....Its been a while since I have posted on here. Little Information before I get into it. My Truck is a 2006 F150 FX4 5.4L with 147,000 Km on it. Have always done regular maintenance, oil changes every 5,000 Km with Castrol Edge 5W20 oil and Fram synthetic oil filter. Most recent work done was the plugs and coil boots about 15,000 Km ago, then I ran into an injector issue about 1,500 Km ago so i decided to replace all 8 injectors with oem motorcraft injectors, msd ignition coils, fuel filter, and motorcraft VCT solenoids.

After all that work was done the truck was running great. At some points while stopped at stop lights I had to actually look at the tach to make sure the the truck was still running because it was running so smooth. The best it has run since I bought it. Now within the last week and a half the truck has slowly developed another misfire and now it is a continuous misfire. Always on cylinder 6. Before all the work was done I had a misfire on #3 due to a bad injector.

Now that I have a constant misfire on #6 I have been trying to do some diagnosing that has been pretty frustrating. I have swapped coils with no change, I have changed plugs with no change, I have checked the injector signals with a snap-on vantage scope and they are all good, and i have also checked ignition coil signals with the vantage as well. This is where I came across something funny. All coils look to have a good signal waveform except for #6. The signal is there but it is all over the place. I tried measuring signal at the coil connector as well as right at the PCM connector. I have also tried swapping coils and looking at the signal again and still looks the same.

I guess my question would be could this potentially point towards a bad ignition coil driver in the PCM which would lead to replacing the PCM? Or is there something else that I should look at before jumping to that conclusion? Any help would be greatly appreciated.

techrep

iTrader: (1)

Have you checked compression yet ?

jwdaniels

I haven't checked that yet. I'm not sure I understand how compression would cause the ignition signal to go all over the place like that. If i have time today I will try and hook the vantage up again today and take some pictures of the waveforms and maybe try to do compression tests as well. Also one thing i did forget to leave out was that every now and again the engine seems to run somewhat fine but usually doesn't last too long.

techrep

iTrader: (1)

What are the exact DTC's that are showing up ?

nrivera04

Fram oil filters.... *cringe*

On to the misfire though... I was first going to suggest a bad plug but it appears you've attempted that. A compression test wont tell you why you're getting erratic signals, but could mechanically tell you the cylinder is fine. My ongoing misfire was due to a cam follower that locked up... I don't necessarily think that's your problem this point though.

Have you checked the condition of the connector? Like peeling back the loom and tracing it. Could be some corrosion or a bad ground causing your erratic signal.

ReaperHWK

I'd check that connector and wires really well.


I'd pull it off the COP, and pull the big PCM connector on the PCM side.


I would then make sure that they are not shorted, ohm them together make sure they are open circuit.


I then would do an end-end electrical test from the connector on the COP to the connector on the PCM; make sure it is a dead short.


I'd also look at the PCM side and make sure those connections are clean and tight; those harnesses are big and they ratchet on.

jwdaniels

Hey thanks for the info....as far as the testing you mentioned i have already done all of the above. checked the connectors at the coil and PCM and they look fine at both ends, disconnected and checked with my multi-meter and compared to i think 4 other coil wires as well and all check out the same. Also when i had the vantage all hooked up and truck running and signal up on the scope I tried moving the harness around to see if it would change the signal at all, but that turned out with the same signal waveform on the scope at all times.

jwdaniels

It was a P0306 #6 Misfire Code......i actually just looked back at my screen shots to December when I scanned my truck and I also got a P0607 Control Module Performance Code that I don't ever remember seeing.....Now Im kind of wondering if that could directly point it to a bad PCM?

techrep

iTrader: (1)

A P0607 could be caused by one or more of the following:

• Loose ground terminal on PCM/ECM
• Dead or defective (12V main) battery
• An open or short in the power or ground circuit
• Loose or corroded battery terminals
• Failed PCM/ECM

jwdaniels

That was back in December though. I haven't had that code come up at all since that one time. Also if it was a bad ground or power issue don't you think it would effect more than just one circuit?