First post here, My 1999 F150 lately has been having issues when idling for more than 5-8 min.. If I sit in park, after about 5 mins the RPM's while start reving then dipping back and forth, occaisionally leading to the engine dying. This will sometimes happen when in drive with the brake held down, when the RPM's rev, the truck will actually jump forward a bit (which has almost cost me in drive tru's) and when it dips the engine sputters, causing it to rev and roughly moving the truck forward.... Any ideas on what my issue is? I've taken it to Autozone and have gotten 3 different answers from as many employees, One saying my fuel pump is going out, another saying o2 sensore, and another saying my idle air flow.... Thoughts please!!! Thanks

 

Hey kidd88. I have a 2009 f-150 with 70000kms on it and mine is doing the same thing after idling for approx 5-8mins as well. The engine light popped on a few months ago while this was happening and i brought it into the dealership to run the diagnostics, and they managed to mess up my pcm and had to replace the whole thing. This got rid ofnthe check engine light but they couldnt recover the diagnostics to determine what was causing my problem. It seemed to have been running fine for the past couple months until tonight where it happened again... Then a google search led me to here! Have you had any luck finding a solution yet?

 

Why didn`t you have them pull codes while you were at Auto zone.

 

Hello Kidd88 and all other members,
I am a new member (Mr. Mac) and this is my first post. I have been having the same problem with my 1985 F150 FI 5.0L but with addittions. My truck RPM's also start reving then dipping back and forth. Recently it has started destroying the Fuel Pressure Regulator. Three FPR's so far. I think I might have a clogged Fuel Filter or Fuel Return Line but not sure. Will let you know if I come up with any possible solutions that might help you.

 

Usually People like for you to start your own thread Mr. Mac. Even if it is the same problem. It is just easier for every one and you may get more reply's. Some people don`t work as fast as others. Pulling codes on your truck would help also. If you don`t know how there is a sticky on how to do it.

 

P0171 is the code that pulls up when they hook their reader to it. I checked into everything that they say would cause that code and I still have my idle problem.

 

My 2001 has started doing the same thing. Has anyone been able to remedy this issue? Thanks

 

System running lean,what is you engine vac? I bet you got a bad hose some where.

 

Thanks i will check it out!!

 

Kid88 has a code and thats what I went off. Yours could be different,you need to pull codes to.