I noticed this a couple of months ago while leaving a light. When I accelerated normally, after a hundred yards or so, I got this clunking/jerking sensation in the truck, almost like I ran over rail road tracks.

It didn't do it again until yesterday when towing my ATV trailer. I went a total of 440 miles, and in that time it probably did it 20 times, usually 2 or 3 clunks at a time. But it is so intermittent it's tough to pinpoint it.

This is really a puzzler. I thought maybe something going on with the transmission? It seems it would do it just after it downshifted to pull a hill. Again, it would only do it 2 or 3 times. The best I can describe it, is is like running over rail road tracks. Any ideas???

 

Check your sparkplugs

 

X2 on the plugs. Mines doing it just randomly. It won't throw a cel just for the spark plugs just if the COP is messing up. When I get time I'm gonna pull em and check them.

 

I have read about plugs being a problem with these, but did not know the symptoms. I just assumed it was rough idle or a miss if they were bad. I bought the truck with 105k on it, and it now has 109, so have no idea if they have ever been replaced but it is something I wanted to get taken care of.

How can I check the plugs without removing them? From what I have read, they can be a b*tch to replace.

 

Just replace the plugs and coil packs. If your proactive instead of reactive you will get alot more miles between part failures.

 

Yeah you can't check plugs without pulling them out. I'm with everyone else on this, it's either your plugs or a bad COP.

 

Excuse my ignorance, but what is COP? Coil packs?

I will be changing plugs at the very least soon.

 

COP means coil on plug. One coil per cylinder on top of each plug. One of Fords greatest ideas...NOT!!!!

 

Get the accell c.op.s much cheaper. When you take off the c.o.p look at the top of the plug, it will have paint on it if its still factory.

 

These?......
http://www.summitracing.com/parts/ac...rd/model/f-150

Are standard Motorcraft plugs ok?