2010 F150 5.4 3V Triton engine Misfires when Cold
Starts fine and regular idle for 20 seconds, then hard misfire on cylinder 4
and 8 until engine warms up, then runs like a champ.
Local Ford Dealer said Piston Rings, I don't buy it. Replaced plugs and coil
packs, injectors and sprayed Carb Cleaner around intake manifold to check
for leaks, no change. My Mechanic said Fuel Pressure was in the 40's range
at startup.
Haven't checked compression on suspect cylinders yet. Is there a sensor
that would change fuel intake from startup to running conditions. It idles very
rough for 9 minutes when it's warm out, about 11 minutes when cold. Once
it's warmed up it runs perfect, no hesitation, no burps or anything. Will
continue to run fine between startups as long as it doesn't cool off to much.
