Figuring out why a large diesel mining machine has a slow auto idle return

[Alan]

You’ve witnessed it, the machine comes off load, but the RPM just hangs there, taking its time before it finally drops to idle. It shouldn’t take this long! What’s the first thing you look into, is it the fuel system, throttle input, sensors, ECM settings, or hydraulics? What’s caused this issue for you before?

 

[Goldshark]

The reason can vary from machine to machine.

 

[Adamms]

First thing I’d check is throttle position sensor and linkage return, then look for ECM idle settings or load signal hanging from hydraulics or fuel governor not dropping cleanly.