LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

High idle

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Old 10-27-2008, 06:24 PM
  #16  
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Originally Posted by BUBBA
As mentioned, the Tach usually reads high, so 1150 with an M6 might only be around 950+-, which sounds right. JMHO
I thought about that, but it used to idle around 1000, 900 when at operating temp. Plus, the RPMs come down slower than they used to with the clutch in. I think I am just going to replace the IAC and see what happens.
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Old 10-27-2008, 06:41 PM
  #17  
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Stock M6 idle is 800rpm fully warmed up. But it has a cam and a program, so without using scan software or asking the tuner, its hard to tell where it should be idling.

When you load the engine with the power steering or the A/C, the IAC motor should open up to keep the RPM within spec. But if the engine is already idling higher than the target set in the program, the IAC isn't going to move in response to the added load, and the engine will slow down. High idle typically indicates the IAC is closed, but the engine is getting air from somewhere else. Or, the PCM has told the IAC to close (counts = 0) but the IAC valve isn't responding.

When the car is rolling, and you put in the clutch, the engine is not going to drop to the "car is standing still" idle speed. When the VSS is indicating the car is moving, the PCM elevates the ilde speed.
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Old 10-28-2008, 12:10 AM
  #18  
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Originally Posted by Injuneer
When the car is rolling, and you put in the clutch, the engine is not going to drop to the "car is standing still" idle speed. When the VSS is indicating the car is moving, the PCM elevates the ilde speed.
I didn't know that, but it answers another question I've had. I'll try to get ahold of Bryan at PCMForLess and figure this out. Unfortunately I don't have any tuning software yet. Thanks Fred.

To 2manyToyz: Did you ever figure out your high idle problem?
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Old 10-30-2008, 12:53 PM
  #19  
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^ hey bro I don't think it's ever an issue of high jacking a thread when the info shared helps us all but i appreciate you mentioning it.

as for the idle i thought i solved the problem by retightening the intake and block off plates but within 10 seconds the idle climbed back up over a 1000. Now the SES does not come on until closed loop though were as before it would come on at start up. EGR is throwing codes and I'll need the tune to zap it. Don't know what else is stored because I've not gotten it scanned. Went to AZ and they said they do not do obd I. Had to correct one of the guys when he suggested using a paper clip. So I'll live with it until I can get scanning equipment. The z is not my daily driver anyway.

btw check out my ride along from a few nights ago http://www.youtube.com/watch?v=c4fy2s9zWfU
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