Help with LT1 idle...
Thread Starter
Pro
Joined: Feb 2001
Posts: 662
Likes: 0
From: Denver CO
Help with LT1 idle...
My 94 LT1 will not idle under 900.
I replaced the intake gaskets, TB gasket and it still will not idle properly.
I have been tinkering with the idle set screw trying to find where it should be, and following each adjustment with the start and hold of the throttle above idle for 10 seconds and still no gains.
It is not throwing a Idle air control, valve code, but will it???
PLEASE HELP!
Cheers,
Robert
I replaced the intake gaskets, TB gasket and it still will not idle properly.
I have been tinkering with the idle set screw trying to find where it should be, and following each adjustment with the start and hold of the throttle above idle for 10 seconds and still no gains.
It is not throwing a Idle air control, valve code, but will it???
PLEASE HELP!
Cheers,
Robert
Burning Brakes
Joined: Nov 2000
Posts: 1,117
Likes: 0
From: DFW TX
Re: Help with LT1 idle... (Bob Mosaic)
I have changed the throttle body, intake gaskets, vacuum hoses, the IAC, TPS, MAP, IAT, O2, knock sensor and every other sensor on my 92 and I have never been able to get it below 900. I've tried all the settings and adjustments that I'm sure some members will chime in with in a few minutes too. I have given up now.
*EDIT* BTW, the only thing that I have done that affected the idle was replace a bad opti. It was idling real high, up to 1200 or above when stopped at a traffic light. But it has never gone below 900. I'm not suggesting you have a bad opti though.
[Modified by 92corvette, 4:48 PM 7/2/2002]
*EDIT* BTW, the only thing that I have done that affected the idle was replace a bad opti. It was idling real high, up to 1200 or above when stopped at a traffic light. But it has never gone below 900. I'm not suggesting you have a bad opti though.
[Modified by 92corvette, 4:48 PM 7/2/2002]
Thread Starter
Pro
Joined: Feb 2001
Posts: 662
Likes: 0
From: Denver CO
Re: Help with LT1 idle... (92corvette)
hmmm...I have no idea wherethe problem coulb coming from either. I am going to change the plugs. If they are not the originals, it may run a little lean and cause an increased idle, but who know. I am getting a little upset over this too.
Thanks,
Robert
Thanks,
Robert
Thread Starter
Pro
Joined: Feb 2001
Posts: 662
Likes: 0
From: Denver CO
Re: Help with LT1 idle... (Bob Mosaic)
Supposedly the opti was replced fairly recently, but who knows for certain with past owners. My AIR tubes have been pluged, so I think this may eliminate the EGR valve. If not I may remove it an plug the hole. HOW DO YOU TEST FOR A BAD EGR?
Thanks,
Robert
Thanks,
Robert
Racer
Joined: Jun 2001
Posts: 435
Likes: 0
From: Clemson SC
Re: Help with LT1 idle... (Greenvette)
Bob, I would check to make sure the stock chip has not been replaced. Idle speed is set in the chip.
Bob, the only thing I can think of is buy or borrow the diacom or datamaster software (or any LT1_Edit software for that matter) and reprogram it for 900 or 850 or whatever RPM you want. :cheers:
Racer
Joined: Jan 2001
Posts: 425
Likes: 0
From: Frederick MD
Re: Help with LT1 idle... (Clemson ZR-1)
Is the throttle coming all the way back to the stop/set screw, could be the throttle cable is too tight. I was trying to remove slop from the cable and had adjusted it to the next hole at the cruise control/ASR diaphram thing, made the car idle fast.
Pro
Joined: Jun 2001
Posts: 717
Likes: 1
From: Loudoun County, VA
Re: Help with LT1 idle... (Bob Mosaic)
My '94 has always idled at 900. It has been in several times for other service and no one has ever mentioned that idle speed as high.
Are you sure that it should be lower?
Are you sure that it should be lower?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Thread Starter
Pro
Joined: Feb 2001
Posts: 662
Likes: 0
From: Denver CO
Re: Help with LT1 idle... (urtoslo)
I think it is the TB sticking. Other than that I have to guess the ecm has been reflashed. It should idle 500-700 rpm (GM specs). I am really pissed that I can't get it to idle properly. Tomorrow I will attack it with mote TB cleaner and PB blaster to see if I can aid the prob somewhat. In the morning it will idle 800 or so, but after that is 900-1100 all day long. M first guess was a vacuum leak. Because if I was getting "false air" the iincreased fuel for enrichment on a cold start would balance the mixture and let the motor idle stighly lower. ALTHOUGH, after and intake gasket swap and not a hint of improvement I am upset and confused.
I will keep you posted of my findings.
Cheers,
Robert
I will keep you posted of my findings.
Cheers,
Robert
Team Owner
Joined: Apr 2001
Posts: 22,267
Likes: 3
From: Dallas TX
Re: Help with LT1 idle... (urtoslo)
idle should be around 600, not 900 (with stock programming).
I idle mine at 800 so it won't die, and it has too much power, i have to hold the brake really hard :D
[Modified by Glock'94, 1:29 AM 7/4/2002]
I idle mine at 800 so it won't die, and it has too much power, i have to hold the brake really hard :D
[Modified by Glock'94, 1:29 AM 7/4/2002]
Thread Starter
Pro
Joined: Feb 2001
Posts: 662
Likes: 0
From: Denver CO
Re: Help with LT1 idle... (Bob Mosaic)
idle should be around 600, not 900 (with stock programming).
It should idle 500-700 rpm (GM specs
Team Owner
Joined: Apr 2001
Posts: 22,267
Likes: 3
From: Dallas TX
Re: Help with LT1 idle... (Bob Mosaic)
idle should be around 600, not 900 (with stock programming).
It should idle 500-700 rpm (GM specs
Glock, the average of 500 and 700 is... 600. I realize it idles too high.
It should idle 500-700 rpm (GM specs
Glock, the average of 500 and 700 is... 600. I realize it idles too high.
If they are low, then i'd say you have a vacuum leak because the IAC is trying to close up to relieve the idle air intake, but it's not working.
[Modified by Glock'94, 1:30 AM 7/4/2002]
Melting Slicks
Joined: Oct 2000
Posts: 2,627
Likes: 8
From: Drag racing junkie Va.
Re: Help with LT1 idle... (Glock'94)
I had a similar problem with my 92, try this:
with the engine off remove the throttle cable at the TB,
restart the engine and check idle speed,
see if the TB is closing all the way by pushing back on linkage.
If it drops TB needs cleaning, if not problem may be back towards the ASR, thats were mine was binding.
Hope this helps, let us know what you find,
Dave :yesnod:
with the engine off remove the throttle cable at the TB,
restart the engine and check idle speed,
see if the TB is closing all the way by pushing back on linkage.
If it drops TB needs cleaning, if not problem may be back towards the ASR, thats were mine was binding.
Hope this helps, let us know what you find,
Dave :yesnod:
