Need help with high idle on sd base tune
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Teching In
Joined: Apr 2019
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From: Connecticut
Need help with high idle on sd base tune Hoping someone can help me out. This is my first time doing a complete tune. It is a LS3 with a .600 lift cam and a 8 stack injection running a P01 ecu with a 2002 camaro stock tune as a base. I put it in speed density, input all the injector data and changed the cylinder air to match the bigger displacement. It fires right up idles at 1200 rpm then takes off to 2000 rpm. All fuel trims and idle control are off. The remote IAC is plugged off so that has nothing to do with the idle. I have plugged every vacuum port and pulled the intake off twice to check for vacuum leaks. I know the tune is lean but do I start tuning the VE with the idle so high? I'm hoping someone can spot something in the tune that is causing the high idle or point me in the right direction. It is a LS3 conversion in a classic Vette if that helps. I have attached the tune and log files
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From: Ann Arbor, MI
To have such a high idle, especially with an aggressive cam, requires a lot of air. Since you say the throttle blade seems to be closed and the IAC is even plugged off, let me ask about your PCV system? I assume you have the vent on one rocker cover or the valley cover connected to the intake manifold; then if your other rocker cover vent is open, has an air filter on it, or you have some other leak into the engine, this can be enough air to give you a high idle.
Try blocking the PCV into the intake manifold. If that works, you might then want to re-enable the IAC (and tune for it). Then setup a working PCV.
Try blocking the PCV into the intake manifold. If that works, you might then want to re-enable the IAC (and tune for it). Then setup a working PCV.
Thread Starter
Teching In
Joined: Apr 2019
Posts: 5
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From: Connecticut
To have such a high idle, especially with an aggressive cam, requires a lot of air. Since you say the throttle blade seems to be closed and the IAC is even plugged off, let me ask about your PCV system? I assume you have the vent on one rocker cover or the valley cover connected to the intake manifold; then if your other rocker cover vent is open, has an air filter on it, or you have some other leak into the engine, this can be enough air to give you a high idle.
Try blocking the PCV into the intake manifold. If that works, you might then want to re-enable the IAC (and tune for it). Then setup a working PCV.
Try blocking the PCV into the intake manifold. If that works, you might then want to re-enable the IAC (and tune for it). Then setup a working PCV.
Thread Starter
Teching In
Joined: Apr 2019
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From: Connecticut
I have HPI 60lbs injectors and and an pretty sure I entered all the info in correctly under injector data. It’s still to high of an idle especially with with the blades completely closed and no Iac. Is there any way to tune it down at this point without causing issues?
We have done several 8 stack setups on stock ecms and on holley. They are very time consuming to tune and require alot of mechanical adjusting. You also need the vacuum tool to put in each stack to adjust each cylinder to get them even.
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Thread Starter
Teching In
Joined: Apr 2019
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From: Connecticut
do you have any luck getting them to idle well? I can’t for the life of me figure out where all the air is coming from. Throttle bodies are all totally closed and adjusted the same at this point. Still wants to idle high even with no Iac or vacuum lines hooked up.
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Verdad Gallardo Yes they idle and drive the same as before we swapped to the 8 stack. You have major vacuum leak or you dont have the throttle body's adjusted correctly. What brand are you messing with? We have done hilborn and borla setups.
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From: Alaska
As noted earlier, it takes AIR flow to support ANY idle speed.
What is base spark timing in the idle cells ? Many tuners will crank in 22 or 24 degrees of idle advance out of habit; Yours might idle okay at 17 or 18 degrees.
Are there some wide swings in the spark map NEAR idle speeds ?
Confirm that the spark advance is same in the IDLE, Low octane and High octane maps.
What is base spark timing in the idle cells ? Many tuners will crank in 22 or 24 degrees of idle advance out of habit; Yours might idle okay at 17 or 18 degrees.
Are there some wide swings in the spark map NEAR idle speeds ?
Confirm that the spark advance is same in the IDLE, Low octane and High octane maps.