I just recently bought a 2004 5.4 4x4 with 179xxx miles. It also came with spectre cold air intake, and after reading a thread on here I'm beginning to worry if it will do more bad than good. Has anyone had any bad experiences with them on the 04s?

 

Unless the engine gas been tuned for it, I would get it off. The 04s can run lean. On the other hand, how long has it been on there? If it is lean, damage may have been done already, so may make no difference.

 

Not sure how long it has been on. And from recent experience with the previous owner, I'm gonna guess he doesn't either. Is there any way for me to tell if I should leave it on or not?

 

Take a look at the spark plugs. If they look as if the tips are burning off or the porcelain looks white, it is running lean. If it makes any kind of pinging noise during acceleration, it's lean.

 

I ran a K&N cold air kit on my '04 for a nearly 100,000 miles. The truck ran great until the day it died in a accident.

 

Gotcha. Great info. Thank you