Ok, working on neighbours truck. Truck started to idle funny today. We changed the fuel filter and cleaned the EGR - any other guesses? It's an 03 with 250,000 KM.

 

Should add that idle is between 617-654 RPM.

 

Any codes?
Any other symptoms, like smoke, power, missing at full throttle, etc?
How is the oil level, how many miles on the oil since change, and what filter?
Does he have any mods, like a tuner, gauges, etc.
Are his batteries testing good (individually) w/ a load tester?
Have you tried looking at the ICP sensor to see if it is oil soaked?

 

No mods. It's his daily driver welding truck. There is no smoke or codes. It just has a loping idle. Ran fine until yesterday when it suddenly started. Put my scan tool to it, but it won't read a lot of information out of the truck, not like my 06.

 

Maybe try to verify the FICM voltage is good.

 

I had a rough idle a couple of years ago in my 2005 6.0. It was in the shop for 2 months, and to the credit of the shop, they didn't change out every part, but seemed to do a careful analysis of it. The only thing they found was that the batteries didn't perform to specs when they got hot. Long story short: the batteries were changed and the problem has not returned for 2 years. I still have a hard time believing it. It's a long shot in your truck, but may be worth taking a look at.

 

I agree with bismic on the ICP sensor. I had similar idle issues last summer/fall and after replacing the ICP sensor . . . smoooooth idle. The failed sensor didn't look that oily from the outside but it failed around the pins in the connector and was a real mess inside. I put a new wire harness on too as many around here would probably recomend.

 

i agree that you should check the icp.

 

Sorry, had to leave the truck while the whole clan went camping. I'll have a look at the ICP on Tuesday.