I have a 02 supercrfew 5.4, dual dynomax cat backs, super chip and K&n cold air intake, and untill about 2500rpm the truck is gutless. I had 35" tires and 4.56 gears and went back to stock tires and 4.56 and the power isn't any better. Asoon as I get to 2500rpm hang on tho, cause it pulls hard. I changed the fuel filter,a nd cleaned the air and I don't know what else todo. Right now I'm at the point that I'm going to get rid of it. It has 71,000kms on it.

 

Did you lose your power shortly after installing the exhaust? That is the biggest no-no people seem to doing is installing exhaust not realizing that 95% of the exhausts actually cause a power loss. Magnaflow is one of the only cat-backs that that actually maintains the low-end torque.

These 5.4's require a little backpressure...

 

A little bit but not much cause I had 35" tires on. So you suggest I should goto just single 3" from the cat back? I'm takin it in to the ford dealer tommorow mornin. That dyno max is dual in dual out exhaust with 2.5 " pipes with 3" tips.

 

I think the exhaust and K&N are the culprits.

If you make the air free flowing, you still have power, but it shifts the power further up the RPM band., which is great for high revving sports cars, but not trucks.

OR
you have some kind of mechanical problem. with stock tire and 4.56 gears you should have a fair amount of grunt.

OR

you have high expectations of truck acceleration. you have a supercrew 4x4 (assuming this because of the tires). this truck by its design wont be the fastest thing off the line (weight and drivetrain losses)

 

Well I'm gonna hunt down a stock air box, I took it into the ford dealer and he thinks it may be the pcm cause all he gets is a p1000 code saying I havn't drove it enough. He blanked it out and told me todo some driving test's and to bring it in monday and if its still the same they are gonna give me a new pcm.

I know it wont be the fastest thing off the line if I have really poor power untill 2500rpm thats no good for 4x4 cause I will have to take a run at everything vs dropping into a hole and punching it.

 

did you ever figure out your problem with your truck????

 

First question is - Can anyone please tell me how to post a new question?? I cannot find anything telling me how to do it so I am posting a question in the reply. sorry..
Second question -- My 2003 Ford F150 standard has been sitting for about 8 months. Just got the starter fixed but now when I shift gears (any gear) is has hardly any power and vibrates (as if it is in 5th gear at 30 mph). I especially have very little power when going up an incline. It also backfires sometimes.
Any suggestions?

 

First choose the proper forum for your question, V8, V6, or the year of the truck will work. Open that forum and in the upper left there is a button for new thread. After opening that, put in your subject then your question.

 

Thank you!

 

since this old thread has been bumped, I'll go ahead and include some useful info for the newbies





it's most likely transmission or torque converter related