04 5.4 CAI lean conditions
I have a 04 f150 fx4 5.4 w/ Afe Cai kit, magnaflow high flow cats,borla xr1 and Gryphon w/ custom tunes for my mods, as the only performance mods. I have been dealing with a lean condition for awhile now. Only happens off idle as FT's are close to perfect at idle, but indicate a lean condition anything above idle. This is also accompanied with what sounds like spark knock, mostly audible at 2k rpms up to 2800rpms under a ~48%-60%+ load doesn't matter what gear or speed. Truck also has lack of power at highway speeds and will throw a lean dtc, but not consistently. I have checked everything possible, fuel pressure is within Ford specs, ~ @ 40psi indicated by rail pressure sensor, FPDM has been replaced as well. no vacuum leaks have been found, fuel trims at idle do not indicate one either. Spark plugs have been replaced with motorcrafts, no misfires present. I have replaced the timing chains, tensioners, guides, phasers and camshaft followers as well due to tensioners failing. Mass airflow has been changed as well,twice with new units and cleaned many times. I have began to think that its the cold air system causing this, but don't have access to a stock intake system to test with. and wouldnt the custom tunes that were written for these mods address that issue?? I just need some more input as I'm at my wit ends here.
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