I got a 2000 F150 with over 200,000 miles on it. Been a great truck, since day one. I't started with a code on the o2 sensors. I replaced all four, since changing one did not seem to help. It idles realy rough, if you power brake it and bring the rpm's up to 800-1000 it smooths out. Not quite perfect, but pretty close, at least you don't feel paniced like it is fixing to die and leave you in a bind at an intersection. I recently had the heater core replaced and for some reason since the replacement, the obd is no longer working, I have tried a couple of different readers and had them plug into at AutoZone and theirs wouldnt get a signal either, so having to get all codes from the odometer. There are alot of things this odometer tells you and not sure which ones are the codes, some of the numbers are not in the code book. Normal driving on hwy or in town it seems to run normal, it just doesn't like to idle, whether in gear or in park. Any ideas ?? I would really appreciate any help on this issue. Thanks

 

You've probly already considered this, but hunt for a vac leak with some intake cleaner. spray it over any hoses going to the intake plenum and watch for sudden related idle changes. I just found a massive one in a rubber elbow that attaches to the intake plenum behind the throttle body.. which runs to the pcv valve. That was the cause of a really rough idle no matter if i was in park or drive. i also found a miss likely due to a bad wire but that was more subtle. The PCV hoses in the back passenger side of the engine are full of T's and elbows and rubber which are also suspect points. Spray around the intake plenum base to look for gasket leaks. If no vac leaks, i'ld try checking/cleaning IAC, EGR, and MAF.

 

Good advice ! Also don't overlook cleaning the throttle body and butterfly.

 

I will do that.. thanks, I did clean the IAC valve and the MAF and it seemed to help but did not solve the problem so I will try the vacuum leak test next, When I do figure it out , I will be sure to let everyone know so maybe it helps someone else out in the future. Thanks ,