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Old 01-05-2016   #7
XfireZ51
 
Join Date: May 2007
Location: Chicagoland, IL
Posts: 9,686
Default Re: Coast down idle speed and idle question ..

Quote:
Originally Posted by mike100 View Post
If it isn't a sticky throttle or a vacuum leak (certainly probable), just be aware that even with the most updated prom from GM that addresses the high idle, these cars have the 'idle hang' during coast until you reach 4 mph or less. Lower than 4 mph and it goes to parked idle of around 750-850.

You can lower the idle targets in the chip programming, but you have to have all the air leaks addressed or it will never achieve them. if you can scan your aldl data, you want to observe the iac counts. They need to be larger than zero...if not it means the idle air stepper motor is maxed out (closed off all the way).
Mike,

Very true. Another issue is if the TB has been disassembled or removed, its very likely the min air(and therefore TPS v) will require adjusting, particularly since porting "encourages" more air to come through the blades.
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