Stalling when lifting throttle

Reply Subscribe

Thread Tools

Search this Thread

May 29, 2006 | 06:00 PM

connellyh

Thread Starter

Racer

Joined: Oct 2001

Posts: 304

Likes: 0

From: sometown new york

Stalling when lifting throttle - Fixed I think

My 99 is stalling when I lift my foot off the throttle. It happens when lifting after cruising, accelerating or coasting. The RPMs drop way low and the car dies. I can feather the throttle and keep it running. I can get the RPMs to stablize and the car will idle at 350-400. After 15-20 seconds, the idle pops back up to the normal 750 RPMs.

This all started after I disconected the battery for about 7 days. Everything else works fine. I figured it would have worked itsefl out by now, it's been a week. I've even tried disconnecting the battery to reset the computer. No luck. Any ideas?

Last edited by connellyh; May 31, 2006 at 03:48 PM. Reason: problem possibly solved

May 29, 2006 | 08:18 PM

cenzo

Drifting

Joined: Jul 2004

Posts: 1,571

Likes: 1

From: Hollywood Md

Codes??

May 29, 2006 | 08:57 PM

azmusclecar

Safety Car

Joined: Dec 2004

Posts: 3,731

Likes: 217

From: Arizona AZ

TPS? Throttle position sensor?

May 29, 2006 | 09:38 PM

connellyh

Thread Starter

Racer

Joined: Oct 2001

Posts: 304

Likes: 0

From: sometown new york

I haven't checked codes. Will do tomorrow.

I didn't think it was the TPS because the only thing that changed was the battery being disconnected. It ran fine before that.

May 29, 2006 | 09:40 PM

sugarwolf

Pro

Joined: Nov 2004

Posts: 601

Likes: 1

From: Wa

Make sure there is no un metered air getting in to the intake. I had my MAF hose come loose and did the same thing. So go check to make sure there is no leaks after the MAf to intake

May 30, 2006 | 03:49 PM

connellyh

Thread Starter

Racer

Joined: Oct 2001

Posts: 304

Likes: 0

From: sometown new york

There are no codes, no air leaks, no vaccuum leaks, no loose wires. Another thing I've noticed, when I come to a stop the RPMs jump back up to 700ish within 1-2 seconds. When I first start the car, it idles at 900 RPMs and slowly falls down to 700ish.

Here is the sequence of events:
car ran fine - disconnected battery - car sat for 1 week - reconnected battery - stalling problem.
Nothing else was touched. The reason I disconnected the battery is because I have the dreaded phantom battery drain and the battery will loose all of it's charge if it sits for a week.

May 30, 2006 | 06:39 PM

mneblett

Burning Brakes

Joined: Jan 2006

Posts: 1,226

Likes: 45

From: Castleton VA

Cruise-In VIII Veteran

Quote:

Originally Posted by connellyh

Just a shot in the dark, but maybe the battery issue is unrelated. On 4.6 SOHC Fords, this problem was frequently due to problems with the idle air bypass -- either a failing idle control motor or crap in the passage itself (i.e., actual air flow didn't match what the computer thought it commanded). I realize the LS1 isn't set up like the 4.6 mod motor, but the same principles still apply.

p.s. I've assumed that you've checked and there's no problems with the throttle position controller harness -- a Q that came to mind when you talked about working on the battery, as the controller is right there below the battery, in front of the engine module.

Last edited by mneblett; May 30, 2006 at 06:42 PM.

May 31, 2006 | 03:51 PM

connellyh

Thread Starter

Racer

Joined: Oct 2001

Posts: 304

Likes: 0

From: sometown new york

I think I found the problem, dirty throttle body. I guess the computer had compensated for the gradual build up of crud and when I disconnected the battery, it lost the learned compensation. On just 2 litle short drives, the car didn't stall. RPMs never dropped below 600. The moral of the story is "Always look for the free and easy fix first."