Idle dip at startup, normal?

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May 19, 2011 | 06:48 PM

airbrush1

Thread Starter

Burning Brakes

Joined: Nov 2010

Posts: 825

Likes: 66

From: Baltimore Md

Idle dip at startup, normal?

Just picked up my first corvette, and I'm getting used to the differences between it and my previous cars.... One small issue that concerns me a bit is that when I start the car, the idle flares up, and then dips to around 400rpm (feels like it wants to stall), idles a bit rough for a few seconds, and then settles to a normal idle...

I'm not really sure what to check regarding this possible issue... Car is an 01 z06, with a lingenfelter built 427, and seems perfect in every other way

any suggestions?

May 19, 2011 | 07:39 PM

dgrant3830

Tech Contributor

Joined: Dec 2006

Posts: 10,962

Likes: 29

From: Van Buren Arkansas

Wounded Warrior Escort '11

Look for vacuum leaks or unmetered air getting past the MAF such the airbridge coming off the bottom of the intake. PCV valve tube to the intake for holes. Pull your codes too.

May 19, 2011 | 08:01 PM

airbrush1

Thread Starter

Burning Brakes

Joined: Nov 2010

Posts: 825

Likes: 66

From: Baltimore Md

Ill work on checking that tonight!

May 19, 2011 | 08:56 PM

Jnape

Burning Brakes

Joined: Mar 2008

Posts: 983

Likes: 36

From: Middle Of Kali CA

Quote:

Originally Posted by airbrush1

Just picked up my first corvette, and I'm getting used to the differences between it and my previous cars.... One small issue that concerns me a bit is that when I start the car, the idle flares up, and then dips to around 400rpm (feels like it wants to stall), idles a bit rough for a few seconds, and then settles to a normal idle...

I'm not really sure what to check regarding this possible issue... Car is an 01 z06, with a lingenfelter built 427, and seems perfect in every other way

any suggestions?

Nice.

The tune on this engine, depending how big the cam is can cause low rpm issues. Surging, bucking and poor idle.

If it runs fine warmed up, I would just ignore it if nothing obvious is found.

May 20, 2011 | 02:36 PM

0Slowhawk

Former Vendor

Joined: Jun 2002

Posts: 2,045

Likes: 3

From: Bridgewater Ma

Alot of times when a Vette starts it will start, go to 1200rpm and dip to 400-600rpm. This is caused by the computers stopping the start surge. I pretty much call it nromal if it goes down to that area and then rises right back to the set rpm IF it does not start bouncing or stall.Should only last 3-5 seconds.

May 20, 2011 | 05:32 PM

airbrush1

Thread Starter

Burning Brakes

Joined: Nov 2010

Posts: 825

Likes: 66

From: Baltimore Md

that sounds exactly like what is happening!

May 22, 2011 | 05:20 PM

yyzmsp

Racer

Joined: Oct 2005

Posts: 367

Likes: 3

From: maple grove and North Port fl mn and now florida

You would not notice this on a stock Vette, but as yours is modded it becomes much more noticeable. I have a LS7 427 with a blower and it does the exact same thing. Simply put when the car first starts the computer is searching parameters and does that little increase /decrease in idle speed. It will all workout but just start the car and let it idle for a minute before you start to drive it or it will stall, as you are changing the air flow while it is still searching the parameters. Enjoy the ride...