[Gmecm] Surging Idle, was: Does $a1 have a "stall saver" algorithm?

Fri Sep 8 18:25:05 UTC 2006

It's possible, but it's a new heated o2 about 10" from the port.  Forcing open loop at idle might be what I'm forced to do if I can't figure out what's causing it to begin with...

Beau Blankenship <ne14roxcj at gmail.com> wrote: Could it be a problem with a lazy O2 sensor or one cooling off at idle? Is
it manifolds or headers, 1-wire or heated O2, how far away from the exh.
port? Maybe tweaking the prop term of the O2 sensor to slow its reaction
time down a bit. Or forcing open-loop at idle or in park?

Beau

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On Behalf
Of Ryan Hess
Sent: Friday, September 08, 2006 12:51 PM
To: gmecm at diy-efi.org
Subject: Re: [Gmecm] Surging Idle,was: Does $a1 have a "stall saver"
algorithm?

Vacuum is about 30kpa.  It's not a vacuum leak, or IAC problem.  EGR has
been disabled in the chip.  

DV Fagan  wrote: Ryan,
What is your manifold vacuum at idle?  You could have
a vacuum leak, an inoperative IAC, or EGR.  Any of
these could be adjusted out in open loop with the
throttle stop and fueling tables but would cuase
surging in closed loop where O2 enters the equations. 
A bad CTS value causes mine to hunt and stall as well.
Dennis
--- Ryan Hess  wrote:

> Well, it is.  I posted this on TGO, but here it is
> again:
> 
> If I burn a chip that runs in open loop, it will run
> all day with a rock solid idle. My P/N switch isn't
> hooked up (workign on it  ), but when I put it from
> P to D, the rpm dips a very tiny amount, but it
> catches it just fine.
>  
>  Now, enter the closed loop chip. BLM's are pretty
> darn good at 126, INT about the same. You let it sit
> for a while in park, and it will start surging.
> Desired idle is 700, and it starts bouncing up and
> down, usually getting more severe each time, till
> eventually it hits 300rpm and either stalls or revs
> to 1200+ and stalls the next time. 
>  
>  Additionally, when in closed loop, if I put it from
> P to D, it instantly stalls. So it's like it has no
> torque or momentum when in closed loop idle. Or it
> can't deal with any sudden changes in rpm fast
> enough??
>  
>  Oh - no surging in drive.  It handles itself just
> fine there...
>  
>  I don't understand what is causing this. How can
> taking out 1.6% fuel can make that much difference?
> There has to be some other idle constant that is
> being "enabled" during CL that causes these things
> to happen..... Any ideas?  TIA,
> 
> Ryan
> 
> davesnothereman at netscape.net wrote:  These are
> conditions to enable EST after startup.  Your engine
> RPM should not be dropping to 300.
>  
> Zaphod
>  
>  
> -----Original Message-----
> From: rgmecm at yahoo.com
> To: gmecm at diy-efi.org
> Sent: Thu, 7 Sep 2006 9:37 PM
> Subject: Re: [Gmecm] Does $a1 have a "stall saver"
> algorithm?
> 
> 
> Wait, what are these:
> 
> Low RPM thresh to disable EST [KESTRPMD] - 300 RPM
> High MAP thresh to disable EST [KMAPSTAL] - 70 kpa
> 
> Both must be true at the same time, then the EST is
> cut?  Does that mean it 
> defaults to the DIS module's advance of 10 degrees? 
> What's the point of that?  
> If idle advance is 16-20, dropping it to 10 would
> surely kill the motor?
> 
> Second, there is:
> 
> RPM thresh to stop Spark Advance Filtering
> [KSFILRPM] - 800
> I don't know what that does, but my RPM is about 200
> lower than stock, should 
> that be lowered too?  (my idle is about 700, stock
> 3.1 idle I believe is 900)
> 
> Thanks in advance,
> 
> Ryan
> 
> Ryan Hess  wrote: I can't seem to find any minimum
> RPM 
> constants listed anywhere....  Any ideas?
> 
> Ryan
> 
>      
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