I have an '01 F-150 4x4 S'crew with 5.4L, 155,000 miles. Idles rough, runs rough (at speed, actually cuts out sometimes at speed), low power, pcv valve is clattering loud and it has no codes.

I did a cylinder drop test (pulled each coil wire, then pulled each injector wire) under load and all of the cylinders are firing fine. It has a recent fuel filter, K&N filter recently cleaned, and no water has been sprayed on the engine. I am at a loss for what next. I am thinking that my convertors may be plugged? Anyone have an idea?

 

Clean the MAF the K&N filters have a tendency to foul them up from the oil.

 

Thanks jgger, I'll give it a try.

 

So,

I did the MAF clean out and that helped a little (about 20%), so I decided to tune up with motorcraft plugs and add the accel super coils...runs awesome now and has power it hasn't had in years (three of my coils were cracked on top).

It still has a very noticeable vibration that shakes the whole truck although the engine is running great. So I was thinking back and last summer I had been on the dunes at Silver Lake and I had hit Test Hill at too sharp of an angle and nosed the bottom of the front end into the dune which caused my skid plate to bend back and up into my fan (which took off one blade). I doubt that one blade off the fan could cause the severity of the shake the whole truck experiences so I am wondering if my harmonic balancer might be gone. I know it's rare but maybe the force of the impact damaged it somehow?

 

One blade off the fan WILL cause severe vibrations. Replace it!

Good luck with those Accel coils, by the way. They have a high failure rate.

 

Thanks glc, I'll change it out. Yeah, my Ford mechanic told me about the accel issues, but I figure if they fail it's ea$ier to replace one Motorcraft coil at a time as opposed to all of them. I have noticed that the accels are louder.

 

Yep...it WAS the fan. Vibration gone.