A little history of the truck first 2013 5.0, 115,000k miles. Truck got a new Dealer installed long block at 111,000 miles, and this is when the problem started. Truck gets the flashing engine light under hard (WOT) acceleration ONLY, pulled codes.. P0300 random multiple misfires. It has done the flashing light a couple times, but now its a solid CEL. I haven't had a chance to pull the codes since the light has come on solid.


My question is, would you guys have any idea where I could look before going to the dealer on why it only happens under WOT? Possibly spark plug gap? I thought about the coils, but seems they would do it under any load and not just hard acceleration. I have towed with the truck since the problem started, and never got any flashing lights under towing load (about 4k lb trailer load), pulled with no issues, no lights, ran perfect.


Any input or ideas are very welcome!

 

Spark plugs and coils would be the first place I'd look.

 

under warranty, take the truck back.

 

CAT clogged?

 

After I installed my boss intake manifold I was throwing that code and couldn't figure it out. Finally realized that I had knocked loose a sensor on the rear of passenger side head. Was barely able to reach it after searching and searching blindly for it and after I finally was able to plug it in tut cured my problem. I think it was cht sensor? Maybe? I know that doesn't sound like that problem and that code would necessarily be related but it fixed my problem.

 

I thought about the plugs, and coil packs, just wasn't sure what everyone thought about the conditions the error occurs. Didn't know if that would point more toward one direction than the other.


I'll have to see if I can find that sensor your talking about. When I first got the truck back from the motor install it ran amazing and was like a new truck, it has slowly gone back to feeling sluggish and boggy. Now this CEL pops up.

 

So, I cleared the codes to clear the CEL light, it happened again, this time I noticed that the light doesn't flash at all when I'm on the throttle, it doesn't start flashing till I let off the pedal. If I keep my foot down it no light, as soon as I let off... flashing CEL.
That make any sense to anyone? Maybe the CAT like CHICKS said? Its going to the dealership today, but they didn't instill much confidence in me when I talked to them, "well, random misfires are really hard to track down."