High idle
Thread Starter
TECH Senior Member
iTrader: (18)
Joined: Jun 2002
Posts: 10,036
Likes: 0
From: NW Houston, TX
High idle At times when I drive the car and then stop at a red light my car will idle at 1500 and sometimes 2000. I dont know what causes this, i bilpped the throttle and my RPM's go up like normal, but go right back to a high idle. I get off the clutch a lil to bog the motor down, and when I get back on it, RPM's go right back there. Its getting annoying and I need to find out what it is. Anyone have a clue. It only does it when its hot, never cold.
If that doesn't fix it, see what fuel trim cell you're in when it happens. If it's not in an idle cell you need to close your throttle body more. You could be right on the edge of the idle tps threshold.
Thread Starter
TECH Senior Member
iTrader: (18)
Joined: Jun 2002
Posts: 10,036
Likes: 0
From: NW Houston, TX
Originally Posted by 2MuchRiceMakesMeSick
Probably an intake leak. Check to make sure your intake screws are tight. Let me know if that fixes it.
TECH Senior Member
Joined: Apr 2004
Posts: 6,157
Likes: 1
From: Texas
Find a stock tune, or if you have yours, load it on there and see if it still does this. It still wouldnt hurt to take a wrench and make sure they are tight. I have seen them where they will idle high sometimes...and other times it will be fine.
Teching In
Joined: Oct 2004
Posts: 4
Likes: 0
I would look at the IAC. Its possible that its stepping motor is acting up when it heats up. Also, you can check for intake leaks with a can of carb cleaner. Spray it around all the mounting surfaces while the engine is running and see if you note an rpm change.
Thread Starter
TECH Senior Member
iTrader: (18)
Joined: Jun 2002
Posts: 10,036
Likes: 0
From: NW Houston, TX
Yes I know it took me a while, but im still having the same problem. I didnt think it was a vac leak, and while doing some logging with HPtuners, the TPS was showing up to 8% throttle position with my foot off the pedal. Anyone know what it could be?
Trending Topics
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
has it always done this? or is it a new thing?
if New... what did you do immediately before it did it?
If always... a vacuum leak would cause high idle always
Sounds like your Idle Airflow table is off....
Do you have a scanner? if so log your IAC values...
TB drilled out at all?
edit: just read your last post.... the 8% can be actual or can be a bad TPS sensor....
Here's what I'd do first....
if it's showing 8%... put your laptop in the engine bay w/the hood open (HPT cable is plenty long)
Try to force the TB closed by hand... does it go to 0? if so then your Throttle cable is too tight.... if you have TCS I can explain how to adjust... (follow the throttle cable back and you'll see a fitting that you can adjust) ... i'm not sure on non TCS cars
if you can force the TB all the way closed and it still shows 8% i'd first reset the PCM (I've seen one car that was showing 17% TPS on idle one day... few weeks later it was fine... I don't know why) using the good ole fuse method or discon battery overnight
If that doesn't fix it... see if someone local will let you try their TPS sensor (it uses 2 star bolts I believe... not sure of size) ...
Also.. is your TB ported? if so by whom? and was it your actual TB being ported or did you do it on an exchange basis? (I've seen issues where people getting TBs on exchange basis had probs since the exchange core was from a junk yard car and the sensor was fubared)
edit2: holy fawk... talk about a thread from the dead! lol....
if New... what did you do immediately before it did it?
If always... a vacuum leak would cause high idle always
Sounds like your Idle Airflow table is off....
Do you have a scanner? if so log your IAC values...
TB drilled out at all?
edit: just read your last post.... the 8% can be actual or can be a bad TPS sensor....
Here's what I'd do first....
if it's showing 8%... put your laptop in the engine bay w/the hood open (HPT cable is plenty long)
Try to force the TB closed by hand... does it go to 0? if so then your Throttle cable is too tight.... if you have TCS I can explain how to adjust... (follow the throttle cable back and you'll see a fitting that you can adjust) ... i'm not sure on non TCS cars
if you can force the TB all the way closed and it still shows 8% i'd first reset the PCM (I've seen one car that was showing 17% TPS on idle one day... few weeks later it was fine... I don't know why) using the good ole fuse method or discon battery overnight
If that doesn't fix it... see if someone local will let you try their TPS sensor (it uses 2 star bolts I believe... not sure of size) ...
Also.. is your TB ported? if so by whom? and was it your actual TB being ported or did you do it on an exchange basis? (I've seen issues where people getting TBs on exchange basis had probs since the exchange core was from a junk yard car and the sensor was fubared)
edit2: holy fawk... talk about a thread from the dead! lol....
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Do you have a FAST 90 mm TB? If yes, TB stick is a real possibility. I thought I had mine cured, but on long drives in the summer when heat can build up underhood, I notice mine will stick, but typically around 2%.
Thread Starter
TECH Senior Member
iTrader: (18)
Joined: Jun 2002
Posts: 10,036
Likes: 0
From: NW Houston, TX
Originally Posted by Ragtop 99
Do you have a FAST 90 mm TB? If yes, TB stick is a real possibility. I thought I had mine cured, but on long drives in the summer when heat can build up underhood, I notice mine will stick, but typically around 2%.
On the way home from classes today it started to hang up at around 1800, then by the time I made it home it was about 1500. I popped the hood and put my hand on the throttle cam and was pushing it shut, but physicly, it was already shut.
I put a good amount of force on it in the direction to close it and they idle just stayed there. Im off at college right now and I dont have HP tuners, it was a friend that was doing the logging for me. 
I have the same problem but I dont' have a bunch of mods done, just a slp flowpac and catback exhaust. I notice it too when I go on a drive for awhile and it's hot out or especially when it's hot out and I get off from the highway and stop at a light it stays up aroudn 1300 or so... I always figured maybe she just needs a tuneup?? But you are explaining that problem to a T same thing happening to my car.
Thread Starter
TECH Senior Member
iTrader: (18)
Joined: Jun 2002
Posts: 10,036
Likes: 0
From: NW Houston, TX
Originally Posted by ShermzT/A
I have the same problem but I dont' have a bunch of mods done, just a slp flowpac and catback exhaust. I notice it too when I go on a drive for awhile and it's hot out or especially when it's hot out and I get off from the highway and stop at a light it stays up aroudn 1300 or so... I always figured maybe she just needs a tuneup?? But you are explaining that problem to a T same thing happening to my car.