LT5 idle strategy (1991) - ZR-1 Net Registry Forums

mike100 · 03-12-2011

So I have the mid 1991 production calibration 'AXFK 0277' chip in the ECM.

Car idles fine parked- I don't know the exact idle (scanner is out for repair), but it looks like 750-800 or so cold, 900 warm on the dash tach. This is fine, my problem is with the IAC scheme when the car is rolling. It would seem any VSS input at all runs a higher idle which drives me crazy as it seems more difficult to drive slow in parking lots and such. It also doesn't like to slow down in the tall gears as much as it should.

I fixed all the vac leaks...I've even blocked off the pcv pipe just to see- it's clearly the strategy of operation.

Is there another later calibration that doesn't run on so high at zero throttle position? I'm going to do a chip soon so I wanted to know if there is a better factory base code to work from.

VetteVet · 03-13-2011

BFXB is the calibration that you want.

03-12-2011	#1
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,802	LT5 idle strategy (1991) So I have the mid 1991 production calibration 'AXFK 0277' chip in the ECM. Car idles fine parked- I don't know the exact idle (scanner is out for repair), but it looks like 750-800 or so cold, 900 warm on the dash tach. This is fine, my problem is with the IAC scheme when the car is rolling. It would seem any VSS input at all runs a higher idle which drives me crazy as it seems more difficult to drive slow in parking lots and such. It also doesn't like to slow down in the tall gears as much as it should. I fixed all the vac leaks...I've even blocked off the pcv pipe just to see- it's clearly the strategy of operation. Is there another later calibration that doesn't run on so high at zero throttle position? I'm going to do a chip soon so I wanted to know if there is a better factory base code to work from.

03-13-2011	#2
VetteVet Join Date: Jan 2009 Location: Mandeville, LA Posts: 340	Re: LT5 idle strategy (1991) BFXB is the calibration that you want.