Hi,

I have a 2007 f150 fx4 5.4L 3v and have been trying to diagnose my misfiring issue on and off for almost a year now...so far in the past six months I have had three spark plug changes from champion to autolite and now motorcrafts that I just put in today! I've got brand new Accel Coils on there and still I am getting random misfiring in all cylinders at various times!! Could it possibly be faulty crankshaft and/or camshaft position sensors?? I hope it's something simple cuz Im ready to burn my truck to the ground right now...and I love my truck.

 

Accel coils have a high out of the box defect rate.

Same truck?

https://www.f150online.com/forums/20...pcm-issue.html

 

ok well I have a brand new motorcrafts coil I will try swapping around and testing each cylinder and using scan tool to see if they are the issue...if not what is my next step in diagnosing this? becuSe I can't see all 8 being bad even if they do have a bad track record...

 

It'll just be less headaches to replace all 8 motorcrafts. Accel are known to be crap, and if they aren't bad now you could be chasing the same random misfire in a year.. Best to just change all to motorcraft and be done.

 

yeah you're right I didn't know Accel had that bad of a rep, but if it isn't all 8 that are bad, what's next thing that I would move on to diagnosing? becuSe right now I have random misfiring in all cylinders and these coils are two months old

 

You need to have it scanned with a diagnostic scan tool a good one. Snap on or the dealer. Other wise your just throwing parts at it. worth the 100 dollar diagnostic charge.

 

I work at a shop and have scanned it with the snap on and ford IDS software that's how I know it's missing in all cylinders, still unable to figure out why...few things you should know that might relate to the cause, I've rolled this truck in the past, did some pretty good damage to it, spent $12,000 at a body shop rebuilding it...never had any engine inspections...possible issues from that?

 

Have been running accell coils for 5 years with no problems. must have gotten a good set.

 

well I just swapped my access out with my stock ford coils I kept and it didn't run any better so back to the drawing board....any suggestions anyone?? help me !!! this is torture driving around, also seems to be at its worst when shifting from four to four lock

 

Since you work at a shop, I would do a compression and leak down test. If nothing else, the tests can give you some peace of mind.
A faulty crank sensor can cause multiple cylinders to misfire, but I would suspect the wiring before the actual sensor.
Have you checked out the FPDM?
Have you determined if the misfires are fuel related, or ignition related?

 

@country-dan


I posted a reply concerning your mis-fire problem - "just posted it in the wrong damn thread" SEE: https://www.f150online.com/forums/20...ml#post5162688


Subject matter of that thread is the same but that makes it far less likely to help you much.


Anyhow, I hope you can benefit from my mis-fire experiences.

 

Just wanted to mention, that these engines are not known for bad compression even after 300k miles, Ford makes pretty durable long-lasting engine blocks, but all the sensors and hydraulic valve timing pieces are what really screw these 4.6l and 5.4l 3v over, I have done the the 2k timing replacement, new vct solenoids, new cam sensors, and new coils, I've also flushed block and changed oil 3times in a 500mile week, and everything seemed to be getting better, but now I'm getting the surging idle and stall with very rough idle and even chain rattling noise I goose the gas to 1500rpm and it mellows out, the only thing I haven't checked yet is the crank sensor which I'm gonna finally do tonight after work, if that don't fix my issue then I'll just order all new injectors and recheck for fouled plugs, my truck is 06 f150 5.4 3v 212000 miles did timing at 198000, CAT delete, cold air intake from spectre, top of the line autolite plugs, new cloyes timing kit, which all Ford's use nowadays, everything else is motorcraft oem, every time I take a step forward with this truck 500mile later something's brings me back, the money a spent on this truck would've fully restored my 76' f150 and the 76' is a beast compared to these fake Ford's we have to deal with today, been thinking about swapping in a 7.3l gaser they have now, the spec and dimensions look good for fit...