Hi everyone,
I put on a throttle body on my 2008 and at first all was well. But now I have this very strange behaviour. Once the engine is warm, the Idle settles around 800rpm. The shifts seems a tad rougher too. But here is the funny part. When I shut the car off and start it back up, the idle settles to 550-600 rpm where it used to be while in Drive. Very short drives around it stays at 550-600rpm in Drive. But if I go a bit longer, and come to a stop... it will settle at 550 rpm, then it seems like something triggers it to go higher and it will go to 850-900 rpm and not settle back until I shut it down and restart it. There are no misfires. I checked everywhere for vacuum leaks and nothing I can find. I have a Tech 2 scanner, is there something I should be looking for?

As I said, my only clue is that I will come to a stop after a few stops and it will stop at 550rpm... then its like something tells it to go higher and it won't go down. Should I try a throttle relearn via the tech2?

Thoughts of anything else?

Matthew

 

post your engine please. Do you have a cable driven throttle, or is it electronic?

The computer will sometimes command a higher idle for things like AC or high electrical loads. Make sure HVAC and any accessories are turned right to OFF, and have your charging system load tested.

 

My engine is a 5.3 L with with electronic throttle. I have thought about the alternator as I sometimes get a strange whining noise coming through the radio. Even with the radio off. It doesn't make any sense to me that this should happen, but it's a funny whining sound. The voltage looks correct on the voltmeter understand why I get that whining sound. And the whining sound. I just noticed this morning gets louder and more noticeable when the command to raise rpn occurs.