number one cylinder is misfireing.Fuel pressure good and verified by dealer.I swapped a new
injecteor and the problem still there. Rough idle. Problem diagnosed by useing a raytech heat gun when engine was cold.
Engine runs smooth above 2000 rpms and has plenty of power. Mpg awesom 22 plus

 

Any noise out the exhuast? Probably melted a piston. hows the blow by? A cold cylinder is not firing due to 2 things:
1 No compression
2 No fuel
remember these engines WILL compensate for a bad cylinder!

 

no noise out the back and the cylinder is fireing . It just takes longer to get hot which shows there is a problem there. All the other cylinders are good. The dealer said that ther is nothing wrong with the cylinders compression. Thats why I have already replaced an injector in but no change. I even swapped a injector from another cylinder but same result.

 

sounds to me like you have a bad injector harness for that injector! any rubbed through wires or broken wires that you can see?? if it is rubbed through it may be shorting out and that could be the problem! hope this helps!!!

 

Thanks for the info. I will check it out. Something happened a while ago that I should mention. I ran out of fuel one day at my house, I know my bad. When I got the truck running it ran totally smooth for about the rest of the day then back to the same rough idle the next day. Any ideas anybody? Is the problem in the fuel supply. I do have a fass fuel pump in it. Should I try messing with the fuel pressure?