General Maintenance & Repairs Leaks | Squeaks | Clunks | Rattles | Grinds
Sponsored by:
Sponsored by: CARiD

RPMs are hanging up.....

Thread Tools
 
Search this Thread
 
Old Oct 30, 2006 | 08:08 PM
  #1  
Pewterpower's Avatar
Thread Starter
12 Second Club
 
Joined: Sep 2002
Posts: 597
Likes: 0
From: Tampa
Default RPMs are hanging up.....

I've been talking about my IAC valve in the external engine forums.

My RPMs don't want to seem to come down much when I lift my foot off the gas. Like when I'm approaching a red light, I need alot of brake, cuz it doesn't come down much below 1200 rpm.

Once I am stopped, after a few seconds it will fall to 550 or so (normal range) and stay there. So I know I don't need to adjust my cable.

If I am stopped, with my foot on the brake, and I release the brake, the RPMs will climb by itself. And keep climbing.......as if I am accelerating by foot. I can get up to 30 mph (eventually) without ever touching the gas pedal.

Yesterday, I got a SES light. It was scanned at ADVANCE and it was (I've forgotten the #) IDLE AIR SYSTEM, HIGH RPM.

I've cleaned the IAC valve several times, so I decided to replace it. But the new one hasn't done any good, either.

It was suggested that I take off my TB and clean it up, which I will do this weekend. But are there any other suggestions?

BTW, this whole thing started after I Seafoamed the TB, so maybe I just have a gob of goop in there somewhere.
Reply
Old Oct 30, 2006 | 08:27 PM
  #2  
staringback05's Avatar
TECH Senior Member
iTrader: (8)
 
Joined: Apr 2006
Posts: 6,695
Likes: 2
Default

thats a good idea about the goop...do me a favor...i want you to check the hardware of the TB....go to the little bosch solenoid unit where the throttle/cruise cables come from...take the black top off and rotate the gears...take your bellow off and when you turn the gears all the way and let them go...see if the plate closes all by itself....this can give u an idea of wether is a electrical issue of the TB or just a hardware issue....check back
Reply
Old Oct 30, 2006 | 08:53 PM
  #3  
Pewterpower's Avatar
Thread Starter
12 Second Club
 
Joined: Sep 2002
Posts: 597
Likes: 0
From: Tampa
Default

I can do that in the afternoon.
Are you talking about the round black thing that is near the battery?
When you say solenoid, i think electrical.
Did you mean servo?

What I'm talking about is the round black thing,near the battery, that has the cables going in and out of it. The rotate around the gear. then they go up to the TB.

Is this the thing you're talking about?

The more I think about it, that is a damn good idea.........

I know the blade snaps closed when I do it by hand, at the TB. But I've never been able to check it by stepping on the pedal. If something is hanging up in that servo, it would cause the blade to hang up, as well. Hmmmmmmmmm....
Reply
Old Oct 30, 2006 | 08:56 PM
  #4  
staringback05's Avatar
TECH Senior Member
iTrader: (8)
 
Joined: Apr 2006
Posts: 6,695
Likes: 2
Default

sorry....yea...thats what i mean, i was thinking cylinder and said solenoid....but thats it...it will control the throttle cable...sometimes when working under the hood one of those black cables will get a nice tug and it will throw that servo out of wack....like i said its a easy way to see if its the hardware or a sensor issue
Reply
Old Nov 2, 2006 | 08:08 AM
  #5  
Pewterpower's Avatar
Thread Starter
12 Second Club
 
Joined: Sep 2002
Posts: 597
Likes: 0
From: Tampa
Default

Well, I did take a look at the servo, and it seems fine. But I didn't do anything else.

Originally Posted by Sneakyws6
I would pull the TB, clean both sisde of it and make sure the IAC port is clean and that the IAC pintle is clean. Reinstall everything and plug the IAC back in, turn the ign on and then unplug it. Turn ign off then back on with the IAC unhooked then back off. Re connect the IAC turn ign on and start car. This will allow the ECM to relearn the IAC open and closed points.
I'm starting to thing that it is just a PCM issue, as was suggested before, cuz the car runs better everyday. Maybe it just needed a few extra cycles to recognize and learn the new part....
Reply
Old Nov 2, 2006 | 10:48 AM
  #6  
staringback05's Avatar
TECH Senior Member
iTrader: (8)
 
Joined: Apr 2006
Posts: 6,695
Likes: 2
Default

i honestly dont see how seafoaming the TB would make the pcm trip into "relearn" mode....hmmm....but if its getting better, then i guess what does it matter
Reply
Old Nov 2, 2006 | 07:10 PM
  #7  
Pewterpower's Avatar
Thread Starter
12 Second Club
 
Joined: Sep 2002
Posts: 597
Likes: 0
From: Tampa
Default

No....... I think the Seafoam may have actually ruined the IAC valve.
Remember, I cleaned the thing several times, to no avail. When I pulled it out for the first time to clean it, it was greasy grimy and very black and carboned up.
But when I bought this new one, and a few cycles had passed, it returned to it's old self.
So I would suggest spraying the Deep Creep after the blade and just wiping the front of the blade with a soaked rag. Not spraying the throat too much.
Reply
Old Nov 2, 2006 | 09:38 PM
  #8  
staringback05's Avatar
TECH Senior Member
iTrader: (8)
 
Joined: Apr 2006
Posts: 6,695
Likes: 2
Default

get on it then....have you change out the valve again?
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
Old Nov 3, 2006 | 01:38 AM
  #9  
yekta's Avatar
TECH Enthusiast
iTrader: (8)
 
Joined: Dec 2004
Posts: 649
Likes: 0
From: Bellevue, WA.
Default

i believe this is a common problem... I think it was last year, i bought used ls6 intake manifold and a ported TB. Besides cleaning, went back to stock TB but it kept on doing the same. So I assumed it was from LS6 intake. Me and my buddy tuned it messed with the idle a lot, as u can see why from my cam It runs almost fine now. Sometimes tho especially I start driving it at high RPMs, problem occurs again for a little while
Reply
Old Nov 4, 2006 | 03:38 PM
  #10  
Pewterpower's Avatar
Thread Starter
12 Second Club
 
Joined: Sep 2002
Posts: 597
Likes: 0
From: Tampa
Default

IT'S FIXED!!! w00t!!

Starinback...........you nailed it. It was throttle cables all along.

I spent the day cleaning the TB, messing with IAC, looking for vacuum leaks, etc...
I had looked at the cables before, but had convinced myself they were OK.
But today, I revisited the possibility of sticky cable, and I found it. It's not something you can see with the eye, cuz a millimeter will make a difference.

Even the guy at ADVANCE let me return the IAC valve and got my $133 back.

It's a great day!
Reply
Old Nov 4, 2006 | 03:57 PM
  #11  
staringback05's Avatar
TECH Senior Member
iTrader: (8)
 
Joined: Apr 2006
Posts: 6,695
Likes: 2
Default

....its like buttaaa
Reply
Old Nov 5, 2006 | 11:17 AM
  #12  
Pewterpower's Avatar
Thread Starter
12 Second Club
 
Joined: Sep 2002
Posts: 597
Likes: 0
From: Tampa
Default

This was such a frustrating problem cuz it wasn't happening all the time.
I would think it was fixed, and then it wasn't.
I thought the IAC fixed it, but obviously not.
So I take back what I said about the Seafoam, it obviously had nothing to do with it.
I changed my plugs right after the treatment, and pulling and moving cables around must have been the culprit.
Reply




All times are GMT -5. The time now is 11:58 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