High Idle problems
Thread Starter
Staging Lane
Joined: Jun 2008
Posts: 65
Likes: 0
From: Ft. Rucker AL
High Idle problems Hello,
I have a 2000 z28 m6. With ms4 cam, ls6 ported heads, headers, BBK intake manifold, and a bunch of other small bolt ons. My question is about my RPM's staying high when I push in the clutch. My RPM's will move up to 2,000 when I push in the clutch and stay their until I come to a complete stop. They will then drop back down to 1,000. Also I recently moved to Ft. Rucker A.L. and was wondering if anybody knows of a good shop to have my car dynoed again. Thank You
I have a 2000 z28 m6. With ms4 cam, ls6 ported heads, headers, BBK intake manifold, and a bunch of other small bolt ons. My question is about my RPM's staying high when I push in the clutch. My RPM's will move up to 2,000 when I push in the clutch and stay their until I come to a complete stop. They will then drop back down to 1,000. Also I recently moved to Ft. Rucker A.L. and was wondering if anybody knows of a good shop to have my car dynoed again. Thank You
I have a buddy that built his T/A and his did the same thing. Turned out to be a leak in the casting of his throttle body. The idle air control and tps were trading off days that they were throwing SES lights because the computer just couldn't figure out what was happening. Therefore my best guess is probably a vacuum leak somewhere
Thread Starter
Staging Lane
Joined: Jun 2008
Posts: 65
Likes: 0
From: Ft. Rucker AL
Ok well I replaced my iac and it seems to still have a problem. It idles good at a stop. The only issue is when I'm driving and press in the clutch or put it in neutral the rpms won't drop.
Trending Topics
On The Tree
Joined: Nov 2007
Posts: 170
Likes: 0
I had the exact same problem, and it took me forever to figure it out...but it turned out being the vacuum hoses behind the intake. I even took them off and looked at them, and didn't see anything...so look close. I bet that's it.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
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
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
Staging Lane
Joined: Jun 2008
Posts: 65
Likes: 0
From: Ft. Rucker AL
Ok, I cleaned the inside of the throttle body, the MAF, and the air temp sensor. I also tried taking the propane around the throttle body and intake manifold. I could not check the vacuum lines behind the intake manifold with the propane because of how far they are back there. The car seems to be running a little better but is still having the issue with the RPM's not dropping.
Teching In
Joined: Apr 2011
Posts: 12
Likes: 0
Get someone to let you borrow a scan tool.
You can watch the idle motor count when it's idling high. If the idle motor counts are close to zero, and the motor hasn't hit its target idle, then you've got a leak somewhere.
What have you changed since the last time the car was tuned? Any changes to the intake/throttle body/heads/cam, etc. will require a change in the base air flow tables.
You can watch the idle motor count when it's idling high. If the idle motor counts are close to zero, and the motor hasn't hit its target idle, then you've got a leak somewhere.
What have you changed since the last time the car was tuned? Any changes to the intake/throttle body/heads/cam, etc. will require a change in the base air flow tables.
Thread Starter
Staging Lane
Joined: Jun 2008
Posts: 65
Likes: 0
From: Ft. Rucker AL
I have changed the intake manifold, rockers, and did some porting on the maf sensor and throttle body. It did this intermittently before but before if I recall right when I hit the brake the RPM's would drop.
I'm thinking about getting a hand vacuum so I can see I'm the lines are holding a vacuum.
I'm thinking about getting a hand vacuum so I can see I'm the lines are holding a vacuum.
On The Tree
Joined: Oct 2011
Posts: 132
Likes: 0
From: 20 minutes from the Valley...
sounds like a tuning issue, especially if you did mods that increase airflow after the tune, mine did the same thing until the idle airflow tables were perfect, vacuum leak should cause high idle all the time, and possible other drivability issues due to air bypassing the maf
Thread Starter
Staging Lane
Joined: Jun 2008
Posts: 65
Likes: 0
From: Ft. Rucker AL
Lately it hasn been as intermittent it seems to do it at all times. Sometimes it doesn't though. Also it dosnt always go to the same rpm most of the time it goes to 2 k but sometimes 1.5 k. I want to have it tuned again, but there are a few other small things I would like to take care of first.
Teching In
Joined: Jul 2012
Posts: 6
Likes: 0
Did you ever solve your problem? Mine is doing the exact same thing, in fact mine if left in gear cruising at low rpm, under 2000, I can actually feel it pulling the car. Like cruise control, then if I push in the clutch motor goes to 2000 and holds, idles down perfect once I stop. If I let the car roll down a hill while idling the idle will go up as soon as I reach a few miles per hour, then slow down and it goes back to normal idle.
Teching In
Joined: Jul 2012
Posts: 6
Likes: 0
LSXR102, 92mm TB, 100mm maf, LS6 stage 3 ported heads, 238/242 113 LSA cam, LS2 bottom end, pacesetter long tubes and offroad y. It was doing this before the block swap. The guy that swapped the block was suppose to also fix the tune so this would go away. However now after the block swap it is worse. I really can't spend anymore money on trying to get this fixed.
Seems to be a common issue. Mine does it too. It is the tune. Try to search "throttle cracker"
My car did not do this until I had it dyno tuned. It has something to do with the IAC, but not sure. Before I car would die coming to a stop, I had the tuner fix that and the RPM hang was the result.
When fully warmed up, mine will hang at 1500 rpms and drop to idle in about 8 secs when driving and coming to a stop
Doesnt happen when the engine is cold.
My car did not do this until I had it dyno tuned. It has something to do with the IAC, but not sure. Before I car would die coming to a stop, I had the tuner fix that and the RPM hang was the result.
When fully warmed up, mine will hang at 1500 rpms and drop to idle in about 8 secs when driving and coming to a stop
Doesnt happen when the engine is cold.