06 5.4, no codes coming up, misfiring steady throttle up hills??? help.

 

How many miles? Original plugs and cops?

 

just turned 36,000 everything Original.

 

Your warranty just expired, that sucks.

 

my 97 expy was just doing that same thing I changed all the plugs and put a new COP on and it runs great! you could have a shop put a scanner on it that can read codes even if there is no check engine light on.My check engine light never came on. So I took it to the ford dealership and they did an engine diagnostics and it showed my misfire was coming from the number 5 cylinder.

 

The dealer is saying that i have misfiring from cylinder 2 and 5, they change the #2 with new spark plug and nothing change, they also said because of my duals that i burned out my cats, is this possible? Duals with no mufflers>>. their not sure of this but their just claiming...

 

check out http://www.f150online.net/forums/sho...d.php?t=316783

I had a misfire under load. It turned out be the injectors. They can also destroy your cats.

I've never heard of cat back work destroying your cats.

Ford recently acknowledged that there's problems on the injectors on the 2005s.

 

The guys at the dealerships come up with some of the craziest reasons why there stuff geeks up sometimes. Anyway, it is probably your coil on plugs(cop) for the 2 and 5 cylinders. It is very possible it the injectors are messing up as well. I personally would change the coils first.(after i have checked the plugs themselves)