Correct Idle Speed?

jryerson · October 16, 2003

I have a 96 silverado 5.7. I was wondering what the correct idle speed should be. The reason I ask is because when it is in park it seems to idle just fine. When I'm in drive it seems like it is maybe idling too low. For instance when I'm sitting at a red light I feel a slight shudder almost like it has a sporadic misfire. If I put it in park it goes away. Any insight to what this may be? Thanks

Chris97K1500 · October 16, 2003

I've heard a few people say the transmission will shake some causing you to think the engine is idling differently. Are the actual rpm #'s changing? I haven't noticed mine changing at all from park to drive. The rpm's usually stays at 700rpm I think. I'll keep an eye on mine driving home this evening and let you know. Chris

jryerson · October 17, 2003

Are the actual rpm #'s changing?

Yes they are. When I'm in park the idle is around 800 and when I put it in drive it drops to about 700. Not sure if this means anything.

frdfandc · October 17, 2003

Your idle without any load on the engine (trans in part or neutral) should be approx 750 rpm's, plus or minus 50 rpms. Now when you put the vehicle in gear, you have now added a load to the engine, therefore it will make the engine idle drop to approx 650-700 rpm's. This is normal for any automatic equipped vehicle, because the engine must now transfer power thru the transmission to the forward or reverse gears.