Which plug is misfiring. It says random misfire. Which plugs going to hell on me?? Truck has 130k on it

 

P300 would indeed be a random misfire----codes like P304 P305 etc would indicate a known cylinder misfire.

You may have a faulty wiring connection or perhaps the crank position sensor is causing this?

Might have to do some digging into the wiring to see if the problem exists there.

 

Hmm, what Is a CMP sensor? I was told that was a possible cause....but I have no idea what that is.

 

Not sure what the CMP sensor would be----I'm still of the thought this is a wiring problem relating to the crank position sensor though.

 

CMP: Crankshaft Monitoring something.....

 

It helps a lot if you actually identify specifically what you're working on.

A P300 means the PCM can't determine the misfiring cylinder accurately or there are multiple misfiring cylinders. Your best bet is to go in and look at the misfire count PIDs in mode 6, test 53 and see if you can get more data. Other faults such as a weak cam sensor or EGR system problems can also cause problems.

 

I have no idea what PID means nor do I know what test 53 is. Can you guys further explain it??

 

Got it to throw another code. Cylinder 4 misfire. Now what do I do. There are no other codes besides the two. What do I do now??

 

Start with fixing the #4 misfire.

 

How do I go bout fixing it? SHould I just replace the COP and the plug??

 

That works about 90% of the time.

 

what about the other 10%. What else could it be?

 

Same issue with a 99 F250SD V10. Getting P0300 and P0308. Changed the COP and plug on #8 and still getting the P0308. Found the double split PCV elbow hose in front of the TB and replaced it. Cleaned MAF and ran a tank of gas with Sea Foam. EGR was just replaced by dealer a couple of months ago. LTFT is good but STFT has a delta of 20% plus. Any other ideas?

 

Whole bunch of things.

PCM, wiring harness and connectors, injector, base engine mechanical concerns (intake leak, valves, rings, other faults, etc), to name most of them.

 

Yep the last 10% is really hard unless you get lucky and not to mention time consuming. I may swap the #8 fuel injector to see if the misfire moves. After that it will be off to the Ford dealer!