stevelaramie

I have a 2004 5.4l f150 with an engine light coded as vacuum leak. I have a k&n intake installed which may be the source of the problem. What do I look for and how do I fix it on my own?

Green '01

The K&N should not send a trouble code - even if you went with a complete cold air kit, as long as the sensors are re-installed in the new elbow. Better chance that the leak is in the vacuum line on the back of the intake manifold. Happed to my '98 5.4L Expy, my sister-in-law's '03 4.6L Expy, and my wife's '03 4.6L Expy also. Some older sevice techs will use a stethescope with a long tube for zero-ing in on a vacuum leak.
Good luck.

Green '01

Oh yeah, I forgot that the late model mustangs usually can't go with an aftermarket CAI without having to reflash the computer, but I didn't think the '06 F150 had the same issue. In any case, I wouldn't think it would cause a vacuum leak code.

99F150guy

i've had to replace all the vacuum line on my 99 f-150, due to crappy hoses ford puts on their vehicles. The main one that gives me issues is the elbow under the air intake manifold....