Engine surging at idle????

[benjamin24]

OK, this is a question for a buddy of mine. He says if he leaves it idle for a little while it will start reving up or surging however you want to call it. His truck is an 08 all stock except for lift and tires.

[greasltn]

Is it only when it's cold outside. Truck has a high idle to warm the engine.

[benjamin24]

It revs the engine up and down?

[genedarrell]

RPM probably not changing that much, probably the egr cycling?? Just a thought

[Cotton-Plant]

read the owner's manual, it states the engine will do this & all is normal.

[brendanlush]

I actually had mine do the same thing last night. It was almost like it had a lope idle or something; it would rev up to about 550RPm then back to 500RPM and just keep doing it. I turned it off then turned it back on and it wen away.

[dieselkane]

Originally Posted by brendanlush

I actually had mine do the same thing last night. It was almost like it had a lope idle or something; it would rev up to about 550RPm then back to 500RPM and just keep doing it. I turned it off then turned it back on and it wen away.

This is becoming really common it seems. I have seen numerous threads, and I too have been having lope idle and smoke problems. More so since I updated to the strategy flash system.

[Big Angry Hillbilly]

Rolling idle is set by something changing the torque request.

See it a lot more with tuned trucks than stock ones. Try turning the A/C or defrost off. It may be the clutch kicking on and off if the idle isn't changing a lot that may e what is going on.