Hey guys, I know this is the obs page but thought y'all might have some ideas. I'm working on a customer's E550 that is idling very high and running rough. It's idling at 1400 rpms and I have codes for the ICP (P1211, I just replaced that sensor) IAH (P0541) and have cylinder contribution codes for cylinders 3 and 6. I'm about out of ideas, I checked the UVCH. I also just replaced the glowplugs, it ran fine right after doing the glowplugs then started doing this. Thanks for any help!

 

Hmm well a lot of different things could cause rough idle. I'm not very familiar with the different sensors and codes yet that these motors make, but I'll throw in a few more ideas to look at if you haven't already.

If you haven't looked closer at the injectors, I'd definitally take a peek at those next. Check to make sure oil is coming out of the oil spouts when the motor is running. Also, try unplugging the injectors individually when the motor is running, and see if it makes a difference in the idle of the motor. If a few injectors aren't doing their job, you'll be able to tell really quick by unplugging them. This of course has to be done with the valve covers off.

Also, try and check the injector armature clearance on the injectors (especially the ones giving fault codes). You have to take the solenoid off, then use a feeler gauge and see how much clearance there is between the armature plate thing and the injector top.

Like new would be 0.004 inches. Anything above 0.0025 should still have the injector working properly, but around 0.002 and under is bad. I had two injectors around 0.002 that were barely firing, and they actually took out two IDMs (before figuring out the injectors were bad).

 

It's really weird though because it came on all of a sudden. If it was injectors I would think it would idle if anything slow... it's idling at 1400 rpms. Before the issue started I had changed the glowplugs because there were several that were out and the icp sensor was bad so I replaced that while I was in there. Also being that it is an E series (van) that complicates things a lot too because to get to anything you have to go from inside the cab... when I did the glowplugs I pulled the turbo so that I could get to everything. I don't know if I could get the valve covers off without pulling the turbo so that complicates things with trying to run it with the valve covers off because the turbo has to be on.