Jakob Donnally

I’ve got a 2004 f150 4.6, started missing so I changed plugs and coils, ran good for about a week then started acting up, some times you start it up and it idles fine and sometimes it idles rough, and when you drive it it runs good as long as you don’t put the motor under any kind of a load, the more of a load the motor is under the worse it misses, as you start letting off the gas peddle you can feel the miss leaving and feel cylinders coming back,when you floor it down into passing gear it’s like it’s down to 3-4 cylinders and will barely pull it’s self, I took it to the shop and computer showed misfire on cylinders and o2 sensors so I changed the 02 sensors but didn’t help.



any ideas appericated guys

gone postal

Search FPDM on this site.

It's a module located above the spare tire which has a tendency to rot out. FPDM goes, or starts going, fuel supply to the motor gets screwed up.

Jakob Donnally

Well I put a fuel pump drive module on today and still same thing, also changed plugs again, and new fuel filter. Any more ideas what it could be

650NutKase

Clogged cats

SCORGE

Just to rebound on what 650 said, drive the truck for a bit...then go underneath and look at the cats. If one is glowing red, it's clogged.