Tuning help needed

[jweir at att.net]

Thr only time I get 4 Mv O2 voltage is when I am 
experiencing a ignition miss-fire.  when a cylinder fails 
to fire it puts excess oxygen into the exhaust and the O2 
sensor senses this as an extreme lean condition (not 
that you are having an ignition problem).  Sounds like 
the main fuel table to me... Open or closed loop shouldnt 
make any difference, I would check either the fuel vs 
load tables or the accelerator pump tables..

Jason Weir

--
88 Wrangler - 155K miles and counting
258 I6, 4.0 head, Cherokee header, 2 1/2 exhaust with 
high flow cat & Flowmaster
GM TBI, Crane 260H Cam
TJ Fender Flares
http://home.att.net/~jweir
CNC 4X4 Member - http://cnc.4x4.org/
			
			
> Thanks.  At the time, we had it set to stay in closed loop until 60% throttle, 
> which we didn't get to at any point during the test drive.  We were going to try 
> leaving it in open loop next to see if that makes a difference at all... trying 
> to narrow down exactly _where_ it's having a fit.  Does the 4mv O2 reading make 
> any sense? It seems odd that it'd drop like that within a second...
> 
> Christer
> 
> ----------
> From: 	MIME :realsquash at yahoo.com
> Sent: 	Tuesday, June 15, 1999 11:01 AM
> To: 	gmecm at efi332.eng.ohio-state.edu
> Subject: 	Re: Tuning help needed
> 
> Check to see if it switches to open loop when you push
> the gas.  Try just pushing the gas slowly, but all the
> way to the floor.  Don't just mash the gas!.  If it
> runs crummy this way, then add/remove fuel from the
> main fuel table.
> 
> Squash
> 
> --- christer.medin at lennoxintl.com wrote:
> > Hi, just subbed to this list -- I have a friend who
> > just got his car together again, with a 379
> > (de-stroked 400) SBC, TPI intake, and Haltech
> > computer.  We finally took it for a spin yesterday,
> > and it runs great until you push the gas a little
> > extra; at 25%+ throttle and around 2000-2500 RPM, it
> > stumbles _badly_.  The O2 readings are in the high
> > 700s right before then, and vacuum is at around 24",
> > but as soon as you step on it, the O2 reading drops
> > to 4mv, and vacuum to 5-7".  If I were to wager a
> > guess, I'd say it appears more related to a sudden
> > stab at the throttle than the RPMs.  Right now
> > timing is setup for 10 degrees initial, and 36
> > degrees coming in full at 3K RPM.  Since you guys
> > live and breathe ECMs, I was hoping you'd have some
> > input here.. thanks!
> > > Christer
> > > > > _________________________________________________________
> Do You Yahoo!?
> Get your free @yahoo.com address at http://mail.yahoo.com
> 
> 
> 
> 
> 
>