fulg01

Hey guys, I have a 2005 F150, 5.4, 149k miles. It runs great except under hard acceleration, such as interstate onramp, towing at WOT from dead stop, etc. It will start hesitating and bucking from about 3000 RPM on, and if I drive it that way long enough the check engine light will flash; one time it actually shut down 4 of the 8 cylinders and wouldn't even stay running. The next morning it cranked right up and ran perfectly, no CEL. My mechanic and the Ford dealership have both worked on it with varying opinions, all of which have been wrong.

Here's what's been done:
All 8 coils replaced with multiple brands, currently brand new Motorcrafts
All 8 plugs replaced with Motorcrafts
Fuel filter, multiple times
Fuel pump
Fuel pump driver module
Fuel rail pressure sensor
Cleaned MAF, multiple times
All 4 catalytic converters (unrelated to this issue)
Multiple rounds of fuel system treatment

The only thing that's been suggested that I haven't actually done yet is replacing the PCM. What the heck else is there to check?? To clarify: no codes or pending codes, it runs perfect, idles smooth, and pulls hard until the gas pedal hits about 3/4 and then it goes crazy.

HELP!! Thanks in advance.

DarrinT04

my guess is a bad/clogged fuel filter. it is possible that when the engine is running at high rpm's and under hard acceleration that their is not enough fuel at the injectors to keep up the rpm's

Screwed05

I had a similar problem when towing or hard driving. My problem would start if the rpms stayed between 2500-3000 to long. Long story short I changed the water pump, and no issues since. The temp rise is not enough to notice on the dash gauge. I was able to see the temp rise on my programmer. It's also a good time to do the hoses and thermostat.

fulg01

Fuel filter has been replaced multiple times, the most recent one has about 50 miles on it.

fulg01

Interesting... how much did your temp rise when this was happening? I have a bluetooth real time scanner so I could probably watch my temp. live.

Screwed05

Its been over a year ago. I'm thinking 215-230*. Once it cool for a few minutes it would be fine till I got back in it hard.

Screwed05

Also the CEL would come on for a minute then go off, and wouldn't show any code when checked.

Ecobuilder

You're still not out of the woods for possible misfires. You'd want to confirm that the fuel injectors are not the cause.

fulg01

How do I outrule them without replacing them? Could that issue lead to the PCM shutting down spark to half the cylinders?

I logged a run this morning while it was acting up a little bit... during the hesitation I logged 100% engine load, 75% throttle position, and the engine temp was right at 188F so I guess overheating is outruled.

djfllmn

iTrader: (1)

how did the timing parameters look?