Hey guys, kinda stumped on this one... My personal truck thankfully.. This issue has persisted since I bought the truck a couple of years ago - basically it's a turd compared to any other 3V 5.4 I've ever driven. I've gone through a whole lot, but the only thing that sticks out are high long term fuel trim and high calculated load.
The back story - a clean truck that I bought off a customer who didn't want to pay to fix it's issues. Had a pile of miles (204k) but was in good shape other than needing some TLC and the usual 3V timing work. So I used all OE parts, a new HV/HP oil pump and went up a grade to 5w30. Also had Trav service the injectors and replaced the fuel filter. Right from the start, it was always a pooch and sounded labored under light acceleration. Timing was correct. Never really looked much into it as the engine always had a noise (turns out it had a spun main AND a spun rod bearing, but hey, it lasted almost 10k miles lol)... I rebuilt a different 3V with all the same, but new goodies that I used on the first. The only difference is that I installed a set of Gibson SS headers. Hoping that the problem had corrected itself with the new engine I took to the road only to find out it hadn't. This time I wanted to investigate - everything I can find looks normal. I have a set of reference values that Ford published for this truck/engine and all that I have looked at are normal accept for the calculated load. They list values at idle, 30 and 55 mph (15-17%, 16-25% and 30-50%) Mine are 20% at idle and 80%+ moving! Trims at idle are close, but rise instantly once I'm underway. Interestingly STFT is basically right, but LTFT will be at least 15% to as much as 30% under load - seems to be more connected to RPM than load as I towed a van back from out of town a while ago and watched trims closely. Even at highway speeds with a trailer and van in tow, trims were 15-20%. But I can see 30 by flooring it down the road while unloaded.
Things that I have done/checked
Rebuilt short block, heads checked
New OE Ford timing chains/guides/tensioners/phasers - and yes, the timing is correct
New O2 sensors with the engine
Verified good MAF
New OE plugs/coil boots
Fuel filter
Another set of freshly cleaned injectors from Trav (thinking maybe the others were gunked up because of seeing constant addition of fuel to the trims)
Checked fuel pressure on the scan tool AND manually via an adapter/gauge - pressure was maintained at spec even under load while trims climbed
Checked exhaust for restriction with backpressure gauge - none
No codes
Probably more things that I have forgotten about
If I can figure out the cause of the artificially high load, I'm sure trims will come down to normal
Any thoughts? Anyone come across this before?
The back story - a clean truck that I bought off a customer who didn't want to pay to fix it's issues. Had a pile of miles (204k) but was in good shape other than needing some TLC and the usual 3V timing work. So I used all OE parts, a new HV/HP oil pump and went up a grade to 5w30. Also had Trav service the injectors and replaced the fuel filter. Right from the start, it was always a pooch and sounded labored under light acceleration. Timing was correct. Never really looked much into it as the engine always had a noise (turns out it had a spun main AND a spun rod bearing, but hey, it lasted almost 10k miles lol)... I rebuilt a different 3V with all the same, but new goodies that I used on the first. The only difference is that I installed a set of Gibson SS headers. Hoping that the problem had corrected itself with the new engine I took to the road only to find out it hadn't. This time I wanted to investigate - everything I can find looks normal. I have a set of reference values that Ford published for this truck/engine and all that I have looked at are normal accept for the calculated load. They list values at idle, 30 and 55 mph (15-17%, 16-25% and 30-50%) Mine are 20% at idle and 80%+ moving! Trims at idle are close, but rise instantly once I'm underway. Interestingly STFT is basically right, but LTFT will be at least 15% to as much as 30% under load - seems to be more connected to RPM than load as I towed a van back from out of town a while ago and watched trims closely. Even at highway speeds with a trailer and van in tow, trims were 15-20%. But I can see 30 by flooring it down the road while unloaded.
Things that I have done/checked
Rebuilt short block, heads checked
New OE Ford timing chains/guides/tensioners/phasers - and yes, the timing is correct
New O2 sensors with the engine
Verified good MAF
New OE plugs/coil boots
Fuel filter
Another set of freshly cleaned injectors from Trav (thinking maybe the others were gunked up because of seeing constant addition of fuel to the trims)
Checked fuel pressure on the scan tool AND manually via an adapter/gauge - pressure was maintained at spec even under load while trims climbed
Checked exhaust for restriction with backpressure gauge - none
No codes
Probably more things that I have forgotten about
If I can figure out the cause of the artificially high load, I'm sure trims will come down to normal
Any thoughts? Anyone come across this before?