So I've noticed this for a little now but lately it's gotten much worse. When the truck goes in to high idle it idles real rough and actually starts to shake the truck. If I put it in to manual high idle (which is like 100rpm higher) it goes away. What could this be??

 

Programming exists in the ECM that will randomly kill cylinders during the automatic high-idle, to try to generate extra heat. It sounds like that is what you are experiencing and is completely normal. Not sure though, why it would become more pronounced suddenly. Maybe someone else can shed some light on it.

 

Thanks for the reply. I was pretty sure my truck didn't have the 3 cyl idle feature tho.

 

My 2005 does it whenever it idles up by itself when cold.Has since day I bought it brand new.If I manually high idle it with the cruise it idles smooth.

 

Not on a CR it doesn't.

The high idle is a different beasty at times. Some will idle smooth, some will go into a lope on high idle sometimes it shakes the truck. The ECU under certain circustance swill split the main event causing a lope situation.

If it has NEVER done this before, I would be looking at injectors as a potential problem.

 

Yeap, what he said.

 

Well that was dumb of me, I thought CR trucks were equipped with the 3 cyl idle. Must be just the VP44 trucks. Thanks for setting me straight.