[Gmecm] $8D IAC stalls engine on decel

[Steve Ravet]

> -----Original Message-----
> From: gmecm-bounces at diy-efi.org 
> [mailto:gmecm-bounces at diy-efi.org] On Behalf Of Tomas J. Sokorai Sch.
> Sent: Sunday, August 27, 2006 6:40 PM
> To: gmecm at diy-efi.org
> Subject: [Gmecm] $8D IAC stalls engine on decel
> 
> Hi guys!
> 
> Well, my GM ECMed bimmer is getting almost into a nice shape. 
> Managed to correct the engine cuts @ 2000RPM by starting 
> modifications from the backup bin I had, but I couldn't 
> figure why exactly it was doing that.... anyway... 
> now I have only *one* big driveability problem left:
> 
> On decels the IAC throttle follower keeps getting the 
> commanded IAC steps down to ZERO. And this happens quite a 
> lot when downshifting, so when it is at zero steps, I push 
> the clutch and I get an instant stall.
> 
> Any ideas of why is the throttle follower getting the IAC 
> down to zero? 
> Shouldn't it be keeping the minimum at a saner value (learned 
> Keep Alive steps for example)??

Tomas, VSS is part of stall saver, in that while you're driving at
highway speed the ECM takes the opportunity to reset the IAC to a known
position.  You should get it hooked up.  But in your case, the ECM
commanding IAC to zero, the lack of VSS may not be the problem.  What I
see on the scan tool is above some speed (30?) the IAC opens
significantly from where the idle routine left it.  Take a look at the
idle strategy document on the gmecm page.  It's on the twiki, under
"papers written by list members", and has a lot of good information in
it.

--steve


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