Just bought a 2001 DeVille, 4.8 Northstar, 25000 miles. Engine performs fine except that idle rpm is 650 after engine warms up. Every other GM I've owned idles at 550. Is 650 the correct idle rpm? If so, thanks for the info, if not what is the correct idle rpm and what could be wrong with mine?
The PCM has a " desired idle speed" If it cant control it or bring it down, it will light the Check Engine Light or you will see a warning in the info center. 650 is fine, BTW is that in and out of gear?
February, 14, 2007 AT 9:57 PM
Thanks Jack. The 650 rpm is in drive. In N it will sometimes read 675 on the info center. Have never had a warning nor check engine light. It's not a major issue because everything seems to be performing fine. Just fuel economy and some wear & tear on transmission at idle.
February, 15, 2007 AT 10:29 AM
Wont hurt economy idling. The trans. You would be surprised how much it is controlled by load, throttle position and speed signal. Wont hurt it idling in gear @650
February, 18, 2007 AT 8:32 PM
Thanks for the reply. I appreciate the time and effort. No further questions.