Are there any diagnostics I could do with long term and short term fuel trims? Long term for both banks are around 10% which from my basic understanding means its leaning rich. Don't know if this is by Ford design or if its an important reading that could mean other things.

 

+10% Long Term Fuel trim is not 'GOOD' - BUT not HORRIBLE. As with many, many, readings from the OBDII system, it is not by itself determinative and demands proper perspective - usually from additional OBDII readings or sources. Such is the case here. FIRST: The PCM maintains an 'array', similar to a 'rubics cube' for storing fuel trim values. I've read/heard different values for the total number of storage cells, but know that it is based at least on RPM and Engine Load. The number at idle will be different than it will at 1500 RPM - will be different at 2500 RPM. All that changes under various engine load conditions all the way up to 'dropping out of closed loop'. I will assume your statement "Long term for both banks are around 10%" is at idle. And you are correct, that leans toward rich (factory default injector pulse widths are being lengthened by ten percent, plus OR MINUS, Short Term Trim amount).


If mean average of Short Term trim is at or about ZERO, that merely indicates the PCM is successfully able to compensate for the condition requiring additional fuel to maintain its desired voltage reading from the upstream O2 Sensors. (If LTFT > 25% & STFT >10%, in closed loop, = Rich DTC). If STFT is positive, LTFT is going to GROW further until the PCM can satisfy itself at mean average of ZERO on STFT.


The condition could be the result of several 'different' things or conditions. For elevated trims at idle I would suggest possibly:
1: 'Unmetered' AIR entering combustion (A small Vacuum leak common to both banks)
2: Dirty - partially corroded injectors (not delivering accurate fuel amount for given injector pulse width).
3: upstream O2 sensors contaminated, aged resulting in degraded calibration and producing slightly incorrect reading for a given oxygen amount at the O2 sensor.
4: general or overall ware / degradation in engine efficiency / power (compression or aspiration timing chain/phasers).


For #1, live monitor STFT and use an unlit propane torch to blow propane all around intake, evap hoses, power brake booster, Oil filler cap --- everywhere. A leak will drive the STFT 'NUTS' immediately.
#2 is a difficult one. Basically limited to running injector cleaners or replace the damn things if considerable high mileage, ie: significantly over 100K.
#3 Replace the O2 sensors if > 100K. IMO, should be done preventatively anyway.
#4 (You're screwed) Lol


Good luck


PS. On the brighter note. More serious timing issues often times show up with unbalanced fuel trims between banks. Your video doesn't sound nearly as bad as mine did, at 212K mi. You could have a timing job in your future, but I do not think your trims have ANYTHING to do with that at this point. For that - remove the oil pressure switch and install (even if temporary) a mechanical oil pressure gauge and VERIFY what HOT IDLE OIL PRESSURE IS (AT FULL OPERATING TEMPERATURE, +30 minutes like @StephenG suggested)

 

Thank you for writing all of this. I will add them to the many things to keep on my radar to figure this situation out!

Sorry to go back to earlier posts, but do are there any videos/other threads that serve as instructionals to cleaning out the spark plug holes? Figured I could knock that out as well as I continue working on the truck.

 

@StephenG here is the idling and hot f150 that you ordered. Let me know what you think.

 

Just sayin !!! Looks like yellow ones to me . I wish I was there to catch all those oem ones you threw out .

 

Good video! Covered all aspects. Also the truck sounds great. I personally don't hear any phaser sound at all. The only sound I hear is the normal loud injectors. I don't see much of a rough idle in the video but I'm sure its easier to feel than see. That sounds and looks like a normal running 5.4 to me. I also agree I hope you didn't throw out the OEM coils as most or all of them were probably good. As for the rough idle I don't know..... maybe you're just overly concerned which isn't a bad thing LOL. I too listen to, and feel every little thing about my truck. It kind of annoys my wife, when I notice every little tick from my tires, and squeak from the doors, or knocks from the driveline.

 

I know I know I need to get rid of them! I'm just really trying to do this scientifically without throwing parts at it. If I can rule out everything else then that will be my first thing to get rid of.

 

That's always nice to hear! But I promise the rough idle is there. I used to ignore/tell myself it isn't there before all my passengers started to complain about it. It's not a huge shake but just enough to drive you nuts.