Idle speed
Thread Starter
Instructor
Joined: Sep 2017
Posts: 111
Likes: 9
From: North East Pennsylvania
Idle speed
First, let me say I'm new to the corvette world and I'm not really a "wrench guy". So here is my question. I've tried to find what I'm looking for with searches on the forum but have not seen what I need.
I purchased a 2003 with automatic transmission in September and I noticed that the idle is around 600rpm which I think is about right. When I let off the brake the car starts moving forward quicker than I expected it would. Also when I'm on a flat road, and I take my foot off the accelerator the car seems to continue for a long time without slowing down very much.
Is there some adjustment that need to be made or is that normal for a corvette?
I purchased a 2003 with automatic transmission in September and I noticed that the idle is around 600rpm which I think is about right. When I let off the brake the car starts moving forward quicker than I expected it would. Also when I'm on a flat road, and I take my foot off the accelerator the car seems to continue for a long time without slowing down very much.
Is there some adjustment that need to be made or is that normal for a corvette?
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
If you have NOT made any part changes and this just started happening then it points to a "dirty throttle body" A stock engine should never have a "hanging idle " in gear when coming to a stop-----
A C5 with a drive by wire T-body does not have an Idle air control valve so the throttle is used during cold starts to add extra airflow--By opening the throttle slightlyirty
A dirty carbon fouled T-body is common on older engines---When the T-body gets dirty
the throttle will open way to much at idle to compensate for the dirt--thus giving you a hanging idle-----Take the T-Body completely OFF and clean it thoroughly with brake clean--Even clean the intake manifold as far in as you can reach with your fingers You will be amazed at the black carbon crap that has crept into your T-Body ALSO clean all the ports in your T-Body Make sure your PCV valve is functioning I would just change it as they are cheap--make sure the PCV hose in good and attached correctly A fouled PCV valve/system will add airflow and again may cause a hanging idle ( like a vacuum leak)
A C5 with a drive by wire T-body does not have an Idle air control valve so the throttle is used during cold starts to add extra airflow--By opening the throttle slightlyirty
A dirty carbon fouled T-body is common on older engines---When the T-body gets dirty
the throttle will open way to much at idle to compensate for the dirt--thus giving you a hanging idle-----Take the T-Body completely OFF and clean it thoroughly with brake clean--Even clean the intake manifold as far in as you can reach with your fingers You will be amazed at the black carbon crap that has crept into your T-Body ALSO clean all the ports in your T-Body Make sure your PCV valve is functioning I would just change it as they are cheap--make sure the PCV hose in good and attached correctly A fouled PCV valve/system will add airflow and again may cause a hanging idle ( like a vacuum leak)
Pro
Joined: Jan 2016
Posts: 550
Likes: 53
From: Fort Myers Florida
Automatic in drive should be 550 and idle 625 at normal temp. Do some maf and intake cleaning and then do an idle relearn procedure too. Do a search for it here its pretty basic and easy to do.
Also you say when you let off the gas it coasts at same speed? Tap the brakes and see if your convertor unlocks and it starts to slow down.
Also you say when you let off the gas it coasts at same speed? Tap the brakes and see if your convertor unlocks and it starts to slow down.
Last edited by midnight01; Feb 19, 2018 at 03:14 PM.
