Hi All!

New to the forum here so any input is appreciated and thank you in advance for any expierence or knowledge shared in helping. Please note: I know there are multiple threads regarding my issue, but wasn't sure how to post to that thread so I figured starting my own would be easier to follow and more beneficial to my specific truck.

Truck Specs:
2008 f250 super duty 5.4l (5.4... I know.. now lol)
78xxx miles
4x4
Automatic

Issue:
P0300 (random misfire detected)
P0307 (cylinder 7 misfire)

Let's start from the beginning...

I was getting the notorious 5.4l ticking sound. After doing research on this issue(this forum mainly... thank you for that) I found that it could be a few different issues including:

Cam Phasers
VCT solenoid(s)
Loud injectors
Valves
Exhaust leak
Loose spark plug
-the list could possibly go on, but these being top concerns or issues to look into.

I took it to my mechanic and wanted him to research the ticking problem. This was my primary concern due to it was getting worse over time. I didn't want to do more damage than what was possibly already done. I told him to go ahead and change the spark plugs while you're checking into what's going on. (I know those plugs can break and I didn't want to do that lol)

At any rate... the plugs got changed to motocraft brand (I know the trucks can be finicky with the parts you put back into them so I went with the motocrafts to avoid any complications.) After the plugs were changed, he told me that the ticking was caused from a blown exhaust manifold gasket (yay me... not internal parts or anything too serious. Sweet!)

I had to reschedule to get the gasket done, but knowing what it was now I wasn't too concerned about driving it. So I did. The new plugs are also in the truck at this time. I drove it the next day and right away.. I noticed a misfire. Thought maybe the plug was bad. I told my mechanic about it and he said... Sounds like a COP to me.

So I get a new COP. Okay.. easy fix. Installed it and still got a misfire. Told my mechanic and he said get another COP. So I'm thinking.. "Okay.. get a new part to fix a new part.. sounds logical.. lol" so I do what he thinks might be best. I replace the COP with another new one and it's still misfiring. The new cops are also motocraft brand as well.

Okay... next step.. he claims it may be a VCT solenoid issue. At this point I don't care.. I just want my truck fixed. So he replaces the driver side solenoid. Still misfiring..

So after doing some research on the scanner... we locate some issues that are the exact symptoms I'm having. Misfire.. at low rpm.. during cruise control.. and a sudden at idle.

This information states for this drivability issue.. to spray injector cleaner/carb cleaner into the engine and possibly clean it out. Makes sense. He did this as well as changed the fuel filter. Also did a pressure test on the injectors to make sure they were good. They were. After spraying and cleaning it out, it was taken for a test drive and it seemed okay... but not perfect. The next day.. the misfire came back.

He said that if the misfire returns, that I need to contact the dealership and see if there is a pcm update. The dealership said there probably is but can't tell me until the computer is hooked up to it. (Of course there is a charge when it's hooked up) again.. whatever.. I just want it fixed. The truck is scheduled to go in next Wednesday for that. If that doesn't fix it, my mechanic said cam phasers possibly bUT still not sure for sure..

Anyone else have some easier/DIY tips/known issues youve encountered.. anything to help narrow this down?

Any help is appreciated..

Thanks,
Austin

 

I'm not professional mechanic, but I am from a Ford family and have a love/hate relationship with all of my Superduty trucks.

P0307
When the P0307 diagnostic trouble code is stored by the Powertrain Control Module (PCM), it is an indication that a misfire has been detected in cylinder 7. More specifically, the PCM detects an increase or decrease in crankshaft revolutions per minute (RPM) that exceeds 2%.

So this sucks because we do not know if PCM is detecting increase or decrease, most likely decrease.


First test: pour in a bottle pr two of Techron and drive the truck to stir things up so you have super cleaning fuel, park it, start the motor and then unplug cop on cylinder #7, RPMs should drop for 10 to 20 seconds, then reconnect, RPMs might jump a touch but probably go unnoticed. Reason is that while unplugged the cylinder and valves are washed with unburned fuel and then you ignite it all, don't worry lots of clean air moving through there. Do this multiple times, for like 10 to 20 seconds each time. This is a cheap way of cleaning the valves. Then test drive for miss-fire.

Second test: Move the Spark plug and COP from #7 to any other cylinder, test drive for mis-fire and get the PCM code. If P0307 then there is potential for a wiring issue from the COP connection backwards. If different code then bad spark plug or cop on that cylinder which would probably be the cylinder you moved spark plug and cop to. Look at the connector for the cop on the wiring harness, you'll probably see small blades of metal that make the elctical connection - think of gently gently adjusting the angle of the blade so that you are ensured of good electrical connection.

 

Hey copper!

Thanks for a speedy reply...

So many things have been done and replaced or thought about that I forgot to mention this too...

Today actually, I did an oil change(just in case, who knows lol) and switched the plug/cop from #7 to #5. I do still have a misfire but I'm trying to be optimistic and hope that when I get a code to pop up that it shows p0305 lol.. fingers crossed.. at least I can start diagnosing the cause of the misfire moving.. plug or cop related. Maybe I'll be on my "3rd 'new' cop" lol.. time will tell at this point.

I am going to try the ideas of unplugging and replugging the cops in and out tomorrow. Specifically on cylinder 7 and now 5 since 5 is where I moved all of the parts from 7 to.

Thanks
Austin

 

You get it.