Idle Tables \ VSS screw-up

[Programmer]

Jason,

IAC counts are "10" ?? Sounds like you've got a vacuum leak.

Lyndon.
-----Original Message-----
From: Jason Weir <jweir at worldnet.att.net>
To: GM EFI Discussion List <gmecm at efi332.eng.ohio-state.edu>
Date: August 11, 1999 8:47 PM
Subject: Idle Tables \ VSS screw-up


>Quick question, assuming all is mechanically right except for the chip
>tuning, what tables can affect the idle quality?
>
>Basically what I have is a 7747 setup on my Jeep's 258 I have it running
>great except for the poor idle quality, I have what acts like an
>ignition miss but I have replaced all ignition components from the dizzy
>to the coil/pickup/ignition module, wired full battery power through a
>relay to the coil, never mind the plugs/wires/cap and rotor so it
>shouldn't be an ignition problem. 
>
>While watching the O2 voltage, when the mixture goes lean the idle gets
>worse.  Making me think its a lean out problem, like how I'd tune a
>Holley carb turn the mixture screw in till it sputters then out, when
>the ECM leans out the mixture it sputters just the same. Without going
>to an open loop idle is there any way to richen the mixture a little at
>idle, when I add fuel to the VE tables then INT and BLM just takes it
>away,  
>
>Some readings from the scanner at idle
>
>700 rpm idle - hunts +/- 50 rpm 
>130 blm - steady +/- 1
>128 int - steady +/- 1
>10 IAC counts -  +/- 2 up and down with the idle
>35-40 kpa MAP 
>0 degrees initial advance
>15 degrees advance in the chip at idle rpm/load
>changing initial timing and chip timing seems to have no affect on idle
>quality.
>
>Anybody have any ideas?
>
>BTW has anyone seen a setting in the 7747 stuff as to VSS pulses per
>mile?  Turbo City sent me the wrong one and it reads half speed. They
>offered what they called a "2-Pulse" and a "4-Pulse" models so I got the
>2 pulse model, I thought that would have satisfied the 7747's 2000 ppm
>requirement or does the 7747 really need a 4000 ppm? I have patched it
>by setting all the VSS stuff to half the chip value but I know thats
>only a temporary Band-Aid.
>
>thanks
>
>Jason
>