I have been able to set my cruise control at 1500 rpm's when idling and now it won't do it. It just goes back to idle, Any suggestions? This is an 1996 8.3 mechanical Cummins
Sounds like the King Cruise Control is failing.
Also I think that idle speed has to be correct to manually increase throttle.
It is most likely Bendix. You need at least 80 lbs of pressure for it to work.
1500 rpm is about 55-60 mph on our coach. Seems high to build air when cold. If normal idle is 600, 1000 will be fine to build air or cool down after a hard pull. 1000 rpm is normal fast idle on ours.
Pierce
Ya, I like an "idle speed for warm-up/building air" of 1,100 or so.