I have a 98 F150 w/5.4L 4WD and I had the "Check Engine Light" come on yesterday. After pulling the codes "P0171 & P0174" I headed to this message board to find the solution. After a couple of quick searches I found the potential culprit. There was a vacuum leak at the 90 degree boot at the back of the engine where the PCV tube goes into the back of the intake. While trying to gain access to get to the boot I removed the Idle Air Bypass Valve and while cussing the Ford engineers that stuck 25% of the engine up underneath the firewall I dropped the gasket for it down into the intake valley never to be seen again. Does anyone know the Ford or Equivalent Part # for that gasket? Also does anyone have a fix for that split boot other then buying the new PCV tube assembly? I'm condsidering Silicone but have my reservations. I like to come prepared when I goto my local Ford Parts desk.

Thanks in advance! This message board is the best thing since sliced bread.

 

HI!... As for the IAC gasket, just get some good gasket paper (material) and trace the gasket surface of the IAC and cut it out. Then use a hand held hole punch to make the bolt holes. It's very easy to do. As for the torn 90 degree boot just take it off and replace the hole vacuum tube with some vacuum hose or go to a local auto parts store and go to the "HELP" section in the automotive department. The "HELP" section is usually a section that has little red backed packages that say "HELP" on them and have unusual odds and ends for your truck. There is always a ton of different 90 degree boots in that section. I hope this helps you out.

 

I had the exact same problem with my 1998 F150 4X4 5.4L. However, it cost me $350 in replacing O2 sensors before my son walked by and said "WOW, that some vacuum leak you got there" and in a 2 minutes found the leak.

After that I went to AutoZone and one of the techs gave me a distibutor cap boot that was the exact fit for the 90 boot and it's better made for the application as well.

Best of luck
Steve

 

Thanks for the help folks! Here lately I've been trying to break myself from hanging on to everything and remembered that I still hadn't gotten to those plug wires from an old plug wire change that I did on my Mustang 5.0L years ago. Used the coil wire boot that goes onto the distributor cap and with alittle hawging out with a drill it fit perfect.

As for the gasket, I got my hand held spotlight out and managed to find that gasket way down in there and made a J-Hook out of some clothes hanger and fished it out.

Still cussed the Ford engineers some more though.

Giddy Up!