Dear 10th gen enthusiasts, i have a problem and i need help, i have a vacuum leak on the passenger side of the engine, and i cant find it, it is making my truck run lean and flagging the p0171 and p0174 codes, i know its a vacuum leak because i can hear it. It was fine for a while but i did some burnouts today (i know it was dumb but it was fun) and now its worse. I have a 4.2 v6 and dont even know where to start, advice would be nice, now it is an 04, but its the f150 heritage so basically a 2003

 

Do a smoke test on it to find a leak. Many videos avail. on line Youtube. You can make your own smoke generator. Many different examples to choose from.....

 

Thank you a ton, i was thinking of doing the old carb cleaner test, do you think that would work?

 

A smoke test is more reliable.

 

There is a PCV hose that runs along the passenger side valve cover that goes from the side of the throttle body to the back of the valve cover.

I had one with a huge hole in it that I replaced.