CM871 Idle Fluctuation

[Skidmark32]

Hello my friends to the south,
I've been beating my head up and down the driveway for about a week now, I gotc a 04 Pete here with ISX 871 and I have changed number four injector after the leak down test and I also replaced the second fuel timing actuator the first one has been replaced already and I am still getting a rough idle angry smoke well not even at an idol or just it's just it's like it's surging, I'm gonna build a liquid eye and see if I'm getting air, any help at all would be great, starting to get expensive with little results

[Rawze]

yes those problems can get expensive fast. If it is not de-mandated, Try unplugging the magic plug (the egr temperature sensor) to close off the egr valve temporarily and see if it smooths out.

[hhow55]

(10-17-2017 )Rawze Wrote:  yes those problems can get expensive fast. If it is not de-mandated, Try unplugging the magic plug (the egr temperature sensor) to close off the egr valve temporarily and see if it smooths out.

Mine is doing the very same thing, idle fluctuation. I unplugged the magic plug, and it smoothed out beautifully. What problem doe's this indicate i have with my cm871?

[Nilao]

Egr flow. That's the only thing that the magic plug changes...except for a possible derate but for the most part I think it is egr gasses that is affecting your idle.

[flonly]

mine has this same trouble before engine rebuild at mr haggs and after. i have another 14000 miles till i take it back for overhead.the only thing we did not do was fuel pump or fuel or timing actuators. and it is demandated already

[Dieselhawk]

Hi Guys,
I'm a little late getting back to you on what I found but better late than never! I'm guessing the vanes were binding up in the back of the turbo or there was possibly an actuator issue although there were no codes. The customer had two identical K200s with CM871 so in the end I swapped every component of the EGR system over between them without any improvement until I swapped the turbo. I dismantled the turbo cartridge from the exhaust housing finding only minor wear to the vanes but maybe all it need was freeing up a little as when I put the faulty turbo on the donor truck it didn't play up. I haven't heard whether it is now playing up or still good as it is sitting in a truck sales yard not working but the truck with the original idle surge every 10 secs is now fine. Thank you to everyone for your contributions.