Commander316

2014 f150 5.0

Mods:

Volant intake
Stainless Works 1 7/8 catted headers
Stainless Works exhaust
Ford 3.73 gears
Livernois tune


Before headers, truck ran fine with gears, intake, and tune.
Installed headers, DTC for P460 and P450 came up
Livernois retuned for headers, no more DTC.
Bout a week ago I was getting a hesitation, bucking, etc at around 3000-3500 RPM. Now it is getting worse, happening at even lower RPM. Checked DTC, getting P308 and P316.

Changed plugs with OE Ford Motorcraft (gapped .050)
Checked coil packs
Checked for clogged cats
Cleaned maf
Checked header bolts
Did a compression test (median is 158)
Had a buddy check the tune. Rear o2s are completely turned off, and he sees a little more timing than what he tunes for.
Livernois does not turn off knock sensor.


What the hell?

Commander316

#8 plug before change, 34k miles




Compression test



cats



misfire test showing #8 and a couple others missing



driver front 02



#8 spark plug after two days

UMJonny

Have you tried moving the coil packs around to see if the misfires follow them?

Fuel filter clean?

Fuel pressure good?

Commander316

yes, i swapped coil packs and problem remained. i have not checked fuel yet, however bad gas ruining an injector is a thought.

EFFEXFO

Switch to an old tune just to see if it persist. Also have you checked afr and fuel pressure readings?

Commander316

i tried the 87 and stock tune. 87 seems to be worse and stock is definitely worse.

i haven't checked fuel pressure

EFFEXFO

Rules out tuning then and points more to hard part. Sounds fuel related judging by its lower rpm or under load miss. You might be on the right track with a bad injector from the looks of that plug.

Feathermerchant

Is swapping injectors doable?

Docboz

Take it to Ford, have them do a neutral misfire relearn. I think the pcm needs to relearn itself with all the added parts you have.

mechanicboy

It's pretty easy, I even swapped injectors post-supercharger install which is much harder.

If the livernois tuner allows you to reset the KAM you should, see what that does. Changing tunes doesn't reset everything in the ECU, some is saved unless you to a KAM reset.

Your mean compression is the mean RPM, not static PSI. You should consider doing a physical compression test. Another test you can do, put a piece of paper on the end of the tailpipe, if it sucks back in at any point then you probably have a bad exhaust valve (usually from running too lean).

P.S. What software are you using for these tests?