I have noticed recently that my truck will sometime fluctuate idle speed. Only does it every now and again. Noticed it the other day while hooking up my camper. I have never looked at the gauge to see the exact RPM numbers while it is doing this. If I had to guess I would say its fluctuates maybe a couple hundred RPMs. Its not much but enough to notice. One time it did ramp up almost as if it had switched to high idle mode. Well the other day after doing some running around, I started it later in the day and noticed immediately that it was idling just over 1000 rpm. Nothing I did would change that. Even at a light with the brake pressed it was still just over 1000. I also noticed that while driving when you let off the throttle it almost sounds like you blip the throttle but I am not doing so. Once home I used Forscan to check for codes and got the following...
P0275 on cyl #5, P2287. I had the P0275 right after I purchased the truck but wiggled the wiring harness that goes to cyl 5 and eliminated that at the time so I'm assuming (hoping) that is just an issue in the wiring harness. Based on the 2287 I guessing the ICP sensor if failing or failed. Any suggestions on further diagnosis before I just replace it? Wouldn't a defective ICP effect the overall performance of the truck other than a high or unsteady idle speed, the truck seems to preform fine. Any advise is appreciated.

 

Never had this symptom, so cant help much, but basic thoughts...is the ICP getting 5v? Maybe just another/the same harness issue. Maybe just unplug the ICP and see how it idles with inferred values. The sensor is easy to replace and not too expensive, so I wouldnt mind terribly throwing that part at it.

 

ICP pressure + IPR% is going up and down with the rpms or stays it constant?

 

Hadn't thought to check that. (that's why I come here, so much more knowledge than me) I'll check both over the weekend and report back. Any other values I should look at?

 

The few times I tell this story.

I’ve had that happen and it was called as an ICP sensor issue before I actually brought it in for service to Keith Browning under warranty. Before the scheduled date, I ran the system diagnostics self check, not reprogram, and it was cured and never returned.

The service manager I called to cancel the appointment said that should have not fixed it. I know it should have not fixed it, and everyone else reading this expects that should have not fixed it. But it did, and along with the engineer that worked for me, we could never figure out why. The only possible answer was if the PCM has a learning aspect that was involved.

It may be a one in a million situation, but it’s free. Mine would hump and emit black smoke.

 

Jack what is this self check you speak of? Can that be done without specific diagnostic tools? Mine isn't smoking or humping but I would say the test if always worth a try.

 

With the cell phone and laptop programs, you can run a KOEO and KOER self-tests to activate and check the operation of all the engine components. I know Forscan does it, I'm sure Torque can as well.