I just did a compresion test and got 420psi in 4 cylinders, 400 in 1 cylinder, and 460psi in 3 cylinders. If the engine is only suppost to have 420psi how is the engine getting higher compresion? Carbon buildup?

If it's carbon whats the best way of removing it? is there a good additive to the fuel to do it?

The best way to deal with it is not to do the compression test in the first place, Tracy...

What you don't know, you don't have to deal with.

I just did a compresion test and got 420psi in 4 cylinders, 400 in 1 cylinder, and 460psi in 3 cylinders. If the engine is only suppost to have 420psi how is the engine getting higher compresion? Carbon buildup?

If it's carbon whats the best way of removing it? is there a good additive to the fuel to do it?

Unless you have some driveability problem i wouldn't worry about it, maybe some WOT operation might break it loose. :o:
Don

Could a worn timing chain/gears (since that would allow the valve timing to be erratic, I would think especially at cranking speed) possibly cause this? Just a thought.
If it's still running good, I probably wouldn't worry too much, maybe go whoop on it a little like daustin said.

Thanks guys, not to worried about it just thought some one might have heard of fool proof method of removing carbon. I just got a Heath 4" exhaust installed so a little whoop on it is in order.

Theres no driveablity issues from the high compression but I was having a issue with what sounded like injection knock (but turned out to be a exhaust leak). In a effort to find the source of the knock I changed the lift pump and injectors on the turbo side. Which resulted in a rough idle condition. I checked the new HO carter lift pump and it only put out 4psi at idle so I changed back to the original pump with 175000 miles and it gives 6 psi, I also dicovered that when I changed injectors that I pinched the return line for the back two injectors with that pain the butt heat shield. So 1 of the 2 was giving the truck a rough idle.