Generation III External Engine LS1 | LS6 | Bolt-Ons | Intakes | Exhaust | Ignition | Accessories
Sponsored by:
Sponsored by:

IAC Motor

Thread Tools
 
Search this Thread
 
Old Aug 31, 2009 | 03:52 PM
  #1  
MYSTIC-1SC's Avatar
Thread Starter
TECH Junkie
iTrader: (14)
 
Joined: Sep 2007
Posts: 3,277
Likes: 14
Default IAC Motor

How much can a bad iac motor effect performance, and how can you tell if one is bad? I have a 2000 z28 with the mods in my sig and when you rev the car in park or neutral it sometimes is slow to return to idle. I was curious if this was all in the tune or the iac motor could be bad or you guys could send me in the right direction as far as figuring out what is causing this. Also when i do a burnout or blip the throttle real quick it has trouble getting the idle figured back out and wants to die sometimes and fall below idle. Let me know what you guys think.
thanks.
Reply
Old Aug 31, 2009 | 04:30 PM
  #2  
W es 6's Avatar
On The Tree
iTrader: (1)
 
Joined: Feb 2008
Posts: 196
Likes: 0
Default

I still have almost your same problem... I replaced my IAC valve and my TPS to no avail, hopefully we can figure something out here...
Reply
Old Aug 31, 2009 | 05:11 PM
  #3  
MYSTIC-1SC's Avatar
Thread Starter
TECH Junkie
iTrader: (14)
 
Joined: Sep 2007
Posts: 3,277
Likes: 14
Default

yea im hoping points us in the right direction.
Reply
Old Aug 31, 2009 | 06:20 PM
  #4  
runtwrestlin's Avatar
Launching!
iTrader: (3)
 
Joined: Apr 2008
Posts: 223
Likes: 0
From: FL
Default

I too have basically the same problem, but it's not too terrible once I've driven the car a few times. If I unplug the battery for a while and then drive it, man does it have a rough time finding the idle. Maybe the PCM relearns the fuel trims to compensate or something; that's just my uneducated opinion.
I've been told that I have an air leak (???), but replaced the intake gaskets and checked all the vaccum lines to no avail. However, in a lil over 2 weeks I'll be getting my rebate back from college (Thank God for scholarships), and I'll be getting the LS6 intake. I mean, I don't really see how the intake could be bad, but I dunno. Can't hurt to upgrade Hopefully y'all will have some responses more knowledgable than mine before then.
Reply
Old Sep 1, 2009 | 07:44 PM
  #5  
MYSTIC-1SC's Avatar
Thread Starter
TECH Junkie
iTrader: (14)
 
Joined: Sep 2007
Posts: 3,277
Likes: 14
Default

Yea it is definetly an annoying thing hopefully we can figure something out to cure this issue.
Reply
Old Sep 1, 2009 | 11:02 PM
  #6  
Hi-Po's Avatar
TECH Enthusiast
iTrader: (4)
 
Joined: Nov 2005
Posts: 712
Likes: 0
From: Florida
Default

You need to hook up HPT and see what the AIC counts are. They should be 45-60ish at hot idle. By adjusting the screw on the TB, you can help the AIC gain some counts. But HPT is going to be your friend if your wanting to find AIC problems.
Reply
Old Sep 2, 2009 | 08:27 PM
  #7  
MYSTIC-1SC's Avatar
Thread Starter
TECH Junkie
iTrader: (14)
 
Joined: Sep 2007
Posts: 3,277
Likes: 14
Default

thanks for the advice. any body else have any tips.
Reply
Old Sep 8, 2009 | 10:30 PM
  #8  
runtwrestlin's Avatar
Launching!
iTrader: (3)
 
Joined: Apr 2008
Posts: 223
Likes: 0
From: FL
Default

Soo... I did as Hi-Po said and scanned the car while driving... When I 1st turned her on and the ECT was ~160 the IAC Position was ~35. When the ECT ~195, the IAC Position at idle would dip down to 8, then back up to ~35, and after driving for a lil while it would pretty much be around 0 when at idle...
When I turn the AC on the IAC Position jumped up to around 70, but then settled around 35.

I'm not sure what to make of it, other than it clearly shows something is wrong if it's sposed to be between 45-60. I took the IAC Valve out of the throttle body and cleaned a decent amount of black deposits off of it, but that didn't seem to make a difference.

I attached my HP Tuners scan. If I need to scan again with different parameters, or anything like that, plz let me know. Any help is appreciated!

PS It's a 98 LS1, stock except for the few mods in the sig
Attached Files
File Type: hpl
idle (rough) 2.hpl (112.0 KB, 140 views)
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo




All times are GMT -5. The time now is 12:50 AM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE