Not your typical high idle thread

[SSpitzer]

I have been experiencing a strange high idle problem even with temperatures in the 50s. As I bring the truck to a stop, and push the clutch in or put the transmission in neutral, the idle will not come down to 750 like it used to. It stays around 1000 RPM. The only thing that will bring the RPM down to normal is putting the truck in gear (this is while the vehicle is stopped) and releasing the clutch to manually drop the RPM. Anyone else experience anything like this before? It doesn't do this every time, however, I would say it does it more than 50% of the time. The dealership said they could not duplicate the problem (of course) and I am now out of warranty.

 

[pwr2tow]

Do you have over 100,000 miles on the truck? Did you report the strange idle before 100,000 miles?

 

[SSpitzer]

Yes I am at 106,000 right now and yes it was taken into the dealership before.

 

[Prairie Dog]

Mine has done the same thing on rare occasion. I was told Cummins is trying to keep cumbustion temps up for emmisions purposes or for the health of the injectors or some dang thing and the computer will adjust up the idle if it senses it may be too cool.

It was discussed here a long time ago ~ pretty sure it's normal.



Scotty

 

[KDOHM]

Mine just started doing the same thing lately, I've got 92,000 miles and has never acted like that before - at any temp. Normally on "high idle" a brake tap or throttle input will cancel high idle, but it has no effect when it gets in these fits. It is very random, usually when engine is warmed up but does not seem to be temp related. I have become very used to the normal high idle behavior and this is not normal. Other things I have noticed is the rpm is not dead n*ts on 1000, more like ~950-975 and a little raspy sounding - not real smooth. And I get an occasional "cooling fan speed" code P0483 on the BDDL

 

[TylerMartin]

My 03 3500 6SPD did the exact same thing for about 2 weeks before the lift pump went. After I had the lift pump replaced (in-tank conversion) it never did it again. The truck had about 70000 miles on it when it happened. Just my $0. 02!



T.

 

[SSpitzer]

KDOHM, you're right about the actual rpm. Definately not smooth either.



I'm not sure why a dying lift pump would create this condition, however, I have been considering doing a FASS so maybe I'll just bite the bullet and see what happens.

 

[Smokey 01]

Mine started to do it this winter. I put on a FASS and it made no difference. It does it more when it's really cold. It never does it all the time either.

 

[KDOHM]

I had the new in tank pump installed when my original died @ 75k - so I'm hoping thats not the issue. I guess time will tell! It seems kind of wierd, never heard of this quirk till this winter.