2013 F150 5.0L

So I was towing a heavy camper (at the very limits of the truck; ran the numbers several times, 100lbs under towing capability) and I kept getting P300 codes. Usually this was happening on steep grades in mountains, but I believe it did happen once or twice during some not too crazy sections of the 2000+ mile trek. There was never any super noticeable loss of power or "rough running", although its possible there may have been a sight miss idling at times in past (very mild tremor, was never too concerned)

I have since replaced all COP, Spark Plugs, and have been running lots of injector cleaner. I also have gotten a SCT tuner with custom tunes from 5 star due to the 4.56 gears I had put in to help with grades.

Any other suggestions or thoughts to what this could be?

Never had this happen under normal driving conditions and it happened on different tanks of fuel (several fill ups)

 

Do you know what the fuel trims are doing under a heavy load? Knowing which cylinders are misfiring would also help narrow this down. Cheap OBD tools can tell you these things.

 

Did you put the tune on just before this trip? It could be related to the tune itself if that's the case. Might be worth it to put the factory tune back in and try it again to see if there is a change.

 

I got the tune and tuner here recently following the addition of the 4.56 gears. I was running the stock tune at the time all this was happening.

As far as fuel trims I have no idea what they were at the time, I should be able to keep an eye on them with the live wire, but I’m not sure what values to expect/what would be considered abnormal.

As far as what cylinders where misfiring I mainly just kept getting P300 multiple random cylinder misfire, don’t recall it giving me specifics every time. I kept clearing the code so I would know if it was happening again. I know it gave me cylinder 6 misfire at least once

 

I got some freeze frame data from my last P0300 code.

Was happening at WOT (possibly as low as 75% throttle x1) in 3rd gear at approx 5000-6000 RPM. Was getting it to happen after cruising at 70mph and then flooring it to WOT.

Also happen once while attempting to see how the shift into 4th was feeling and accidentally dropped it to third (75% throttle approx, this was the most recent instance of code I believe, (not sure which instance this freeze frame is )

I got this code 3x with no loss of power/limiter ever kicking in. Currently running 5* 87 eco tune


What y’all think about these cat temps?






Fuel trims yaaa or nay?

I calculated AFR as 12.31 off this EQ_rat… is this correct on E10 Gasoline?

 

Fuel trims look good, at least in the ff. Is there any spark knock when this happening? Does that scan tool have mode 6?

 

No mode 6 on this scanner, was wondering if any of the free loaners at the auto parts stores might have mode 6?

when I got home and pulled the codes again I was also showing misfire on cylinder 1, 3, 4, and 8. The last one is kinda throwing me off as it’s the only one on the opposite bank.

was thinking it could possibly be a restricted cat? But idk

my live wire was showing knock sensor readings of about 1-2.5 ( possibly as high as 3 for a brief second) while running WOT. When just running normal I frequently get readings down to -8 on the knock. Occasionally I’ll get a 5.99 at low speeds/rpm with very light throttle that quickly disappears (I believe this to be false reading) never herd any concerning noises with it and it happens with different octane fuels from different places

These codes where while running 89 octane and in the past while towing I got them while running 93 octane, but I didn’t have the live wire then

Currently running the 87 eco tune from 5* when I got these last codes to fire. I was really pushing it in attempt to mimic jayco pulls, doesn’t happen at all when daily driving.

was running stock tune when codes fired in the past while towing

 

Unless the restriction is equal on both banks, usually fuel trims will go lean on the least restricted bank, so I doubt that's it. I'm not sure of the behavior of the pcm when switching tunes, but it's possible you may need to have the misfire profile relearned. I can do that with my snap on scanner, but not sure about your sct.