Cummins QSM11 surging a little at idle

[Jeremygavin]

My port engine surges a from 600-630rpms sometimes when i come off a cruise.
It doesn't happen everytime, maybe 20%-30% of the time. It will go away after idling for a few minutes. It seems to go away in gear. Nothing else seams to have changed regarding fuel usage, engine temps, etc.. I follow franks fuel treatment system and fuel filters were changed at the beginning of the season and filter bowls look clean. What else can i check?

 

[tc410]

Mine never did that. What does your Cummins tech think?

 

[Jeremygavin]

Mine never did that. What does your Cummins tech think?

I haven’t gotten that far yet. I figured I would start here and see if there was something I can diagnose before bringing in a Cummins tech

 

[ttmott]

Check the idle validation switch on the throttle. Also make sure C-Cruise is off.

 

[Jeremygavin]

Check the idle validation switch on the throttle. Also make sure C-Cruise is off.
View attachment 74301

Will these apply if I have DTS? What is C-cruise?

 

[ttmott]

Will these apply if I have DTS? What is C-cruise?

My bad 2011 boat - I believe they deleted the C-Cruise features.
Regardless your throttles should still have the idle validation switch which may or may not set the idle RPM. Just an educated guess.

 

[Jeremygavin]

My bad 2011 boat - I believe they deleted the C-Cruise features.
Regardless your throttles should still have the idle validation switch which may or may not set the idle RPM. Just an educated guess.

Ok, I will look into it. Thanks for the suggestion.