04 6.0L here. Engine is surging about 200-250 rpms at idle. My truck normally idles at around 600-650 rpms. I have been getting a surge when it is idling. The surge usually drops to about 500 rpms the goes up to 750. It usually does it after it warms up. If I turn on the high idle it runs fine with no surge. Any suggestions?

 

Does your 04 have an 03 motor--ICP sensor under the turbo or on the passenger side valve cover? If it's under the turbo it's an 03 motor and that's most likely your problem.

 

my 04 does that once in a while, my icp is on the passenger valve cover and i usually unplug it , spray some contact cleaner on the contacts and plug it back in, usually will not do it again for a year or so..

 

It's a late 03 motor and the ICP sensor is under the turbo. I will try cleaning the contacts to see if that helps. Would it usually throw a code? I will check for codes tonight.

 

It usually throws a P2285 for the ICP. Try disconnecting the sensor and see if it still surges. Also, if the connector is full of oil then the sensor is leaking and needs to be replaced but not full of oil doesn't mean the sensor isn't bad either.

 

Thanks. I will check out the ICP tonight. I have become a pro at getting it out of there. I can have the ICP and the IPR out in about 15 minutes when the engine is cold and that is without the special socket for the IPR and without the truck on a rack/lift. LOL

 

The wiring harness and the pigtails that plug on to the various engine sensors are connected by crimps (probably assembled in Mexico,....which could explain part of the problem). Check for a bad connection here before throwing too many new parts at it. Wiggle the wires while the engine is running and see if it acts up. When you solve the problem please post again.

 

There were no codes. I unplugged the ICP and the plug was a slightly oily. I cleaned it with contact cleaner and plugged it back in. The surge is intermittant so I have to drive it a while to see if it contiues. I am assuming since the plug was a lil oily that the ICP is definitely leaking a needs to be changed?

 

x2 on icp, It will not always activate check engine light, and on my truck the p2285 code was intermittently stored as a pending code. I had surging at idle and on the highway, very random maybe once a week, I changed the icp and cleaned the oil on the connector and no problems since.

 

Tim was suggesting start the truck with the ICP unplugged and see if your surging goes away. The PCM will go to a default with the ICP unplugged. When mine went 3 years ago it would surge at idle, sometimes die when you rolled up to a stop and rolling down the highway it would act like you shut the engine off...then come right back to life. I'll 3rd the ICP sounds suspect.