xboxundone

I have 2001 F150 Supercrew with 5.4L V8 (recently had a coil pack issue but fixed it and also got a tuneup) been running fine now for aobut a month..

but today i started and it died, then started run fine except the RPM was jumping from 500 to 700 this is with ac turned on, turn AC rpm jumps from 500 to 600 its back and forth sometimes it drops below 500... any ideas of issues? i think my compressor may be going out but i don't think it is the full culprit cause i can turn AC off and seems to still ahve some issues at Idle in or out of gear.

Any thoughts?

billybix76

Just a wild shot, but dirty MAF and throttle body can cause symptoms you describe. If you clean them use TB cleaner or CRC electronics part cleaner not Carb Cleaner...

cowboyCadillac

Not sure it's the same but our Honda Civic was doing that and I cleaned the Idle Air Control valve (IAC Valve), replaced the front O2 sensor (because it threw a code) and the idle went back to normal. The dirty IAC caused the mileage to drop too.

Everyone in the parts shops told me I would need to replace the IAC (~$240). I was pretty bummed because it was just a glorified choke. So while I was waiting for the part to arrive later in the day, took apart the old IAC and cleaned all the carbon. I had to put it back in to go get the new part and the codes cleared. Never came back.

So the long of it is... I'm not sure if the 5.4 has the IAC but maybe cleaning it would be good.

wde3477

x2 on the IAC - inspecting it would be a good place to start.