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

Adjusting Idel

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Old Jun 6, 2005 | 03:04 PM
  #1  
c0rey's Avatar
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Adjusting Idel

Hey I was wondering if I can adjust the idel manually or do I have to do it through the pcm. I have the cable and laptop just need a program to do it. Let me know.
Old Jun 6, 2005 | 04:37 PM
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Re: Adjusting Idel

The PCM controls idle based on the idle speed programmed in the tables. You need software to alter it. You could open up the throttle blades and increase it, by opening the blades until the IAC counts bottom out at "0", but that's not the best way to do it. You would need a scanner to know when the IAC had bottomed out, and to make sure you hadn't screwed up the closed throttle TPS voltage by opening the blades too far.
Old Jun 6, 2005 | 04:40 PM
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Re: Adjusting Idel

what about that screw on the TB where the throttle rests on...cant that be brought out a lil bit?
Old Jun 6, 2005 | 08:47 PM
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Re: Adjusting Idel

I just noticed the screw thanks.
Old Jun 7, 2005 | 10:26 AM
  #5  
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Re: Adjusting Idel

Originally Posted by phinger23
what about that screw on the TB where the throttle rests on...cant that be brought out a lil bit?
That's the screw that adjusts the throttle blade opening. You can't adjust idle with that screw until you have it out so far that the IAC counts are down to "0". As long as the IAC motor can move closed more, it will bring the idle right back down to the value programmed in the PCM. By the time you get the blades open far enough, you may screw up the TPS voltage. Then you need to slot the TPS sensor so it can be rotated to adjust the voltage.

Instead of hacking things up, why not figure out why its idling slow, and fix the problem the right way, rather than cover it up?
Old Jun 7, 2005 | 10:31 AM
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Re: Adjusting Idel

Originally Posted by c0rey
Hey I was wondering if I can adjust the idel manually or do I have to do it through the pcm. I have the cable and laptop just need a program to do it. Let me know.

Free scan can adjust idle at least on a '95. It is free also. Do a search under freescan.
Old Mar 19, 2006 | 02:47 PM
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Re: Adjusting Idel

Mine idles at about 1000 rpm at a redlight and always has. I would like to lower mine just a tidbit or should i not touch it?
Old Mar 19, 2006 | 02:50 PM
  #8  
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Re: Adjusting Idel

Stock programming for the M6 cars is 800rpm. The stock tach is typically off by reading 100-200rpm higher than actual. Your engine may be at the correct idle speed. Only way to know is to put a scanner on it and read the RPM from the PCM.
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