Hi, new to the board here and I'm looking for a little advice....

I have a 1999 ford f-150 with a 6 cylinder engine + standard (manual) transmission...

This past weekend I drove to a different town about 400 miles away. About halfway there, I noticed a screeching noise which seemed to occur randomly from the engine. 3/4 of the way there, the "check engine" light came on and when I got to my destination, the engine ran rough and fluxuated extremely in it's pulling power. (it felt like it was sputtering)

So, I took it to a repair shop on Saturday and the tech diagnosed it as needing a new "cam sensor". I had that replaced and I also had the sparkplugs replaced. Two of which were fouled up pretty good. On my way back, the "check engine" light came back on, and it seemed to have the same engine roughness as before - only no screeching noise this time - just the "sputter" in the engine. It doesn't seem like an emergency sort of thing, but it's freakin' annoying! Plus, I imagine it could lead to more serious problems later.

There are no problems at idle, or at high RPM's - with no load (in neutral). This only happens while pulling at low (2,000) RPM's.

Help!

I had the same problem on a friend's '99 windstar. It has a 3.8 liter V6 which is what your 4.2 liter is based on. Check Engine light had been on, it would also "buck" in the 2700-3000 rpm range, and lastly, it would have a screech sound that came and went, usually while driving but every once in a while it would screech at idle. We wasted a lot of time focusing on the fanbelts because they sound EXACTLY the same way when they go bad, but eventually realized it was the camshaft sensor synchronizer. This is the aluminum piece that the black plastic cam sensor sits on top of. It has a shaft that spins inside that wasn't getting enough lube, we replaced it and the noise and symptoms went away! Hope this helps

thanks for the reply...

I went to Autozone yesterday and the tech diagnosed it as the same thing - the cam sensor. So, I bought the truck manual and indeed found out that there are more parts to that particular sensor - including the shaft you described.

The shaft needing more lube or replacement would explain the screeching noise. I unfortunately don't know if the repair guy replaced just the sensor, or the entire thing... he did charge me around $150 for the part though - which was a legit price according to the invoice he had.

Anyway, the truck is still doing the same "bucking" motion, so I think I'll get into the engine compartment this weekend and check it out.

If it doesn't turn out to be the sensor itself, could it be the wiring TO to sensor? Is this an easy thing to figure out? I heard the problem might also lie in the computer itself! I really hope this isn't the case!

When i wrote about fixing the windstar, i didn't mention we had some invaluable help in the form of a ford driveability tech. I spoke with him on wednesday and he said that he never focused on wiring or computers unless someone had screwed with it(like collision work or major engine work). He said that the screech noise, cam sensor codes, bucking/jerking symptoms, and check engine lights, are very strongly associated with ill-lubed synchronizers. If you choose to do this yourself replacement it is not difficult, but it has to be properly aligned. Just mark the exact position of the "vane" on the cam synchronizer shaft, to the synchronizer's aluminum body and duplicate that alignment with the new synchronizer. Also, the synchonizer went for $120 and the cam sensor goes for $56(parts prices only - no labor)

You just verified what a mechanic told me today! I decided to take it in to the place my dad takes his car to today and he said there was no wiring problems. Instead, he found that the cam sensor (the piece that the OTHER mechanic replaced) was shot again! The reason? The syncronizer "vane" was bent, and was damaging the inside of the cam sensors. He'll replace it on monday. It's amazing how bad a car will run without this tiny part.

I called the other mechanic, and fanaggled some kind of refund for his work as well.

Well, thanks to you for your help!