CM871 Idle Fluctuation

[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.