ZR-1 Net Registry Forums - View Single Post - Coast down idle speed and idle question ..

mike100 · 01-05-2016

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).

01-05-2016	#6
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	Re: Coast down idle speed and idle question .. 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).