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Re: Low O2 readings in Diacom at WOT.... please help!



Just to add a little, though it does not sound like the case? when you run
real rich, the o2 will cool off and the readings will drop to 200, 100 mv or
maybe less (heated o2 as well).  Have someone else drive then follow behind
when it bogs down and see if your butt is black ;-).

Jeff M


> > > I hooked up Diacom on a buddy's '87 Vette this past weekend. During
> idle,
> > > everything seemed normal. O2's were ranging from 100 to 800, up and
down
> > > like they should. But, when he hit WOT, the O2's went to 40 and stayed
> > > there!!!
> >
> > Ya need to find a diagram of the slew rate of the O2 sensors voltage,
and
> > maybe read up on them some more.  I might be a bit lean, but you said it
> > runs great, well it can't be too lean or it wouldn't be running to good.
>
> Well, that's what's puzzling me.... yeah, it can't be too lean if it's
> running so good!
>
> But 40 seems too low running good or not! I mean, it stays that low the
> entire time at WOT, never goes over 60, then when you let off the
throttle,
> it goes to 800 and back down like normal. I'm guessing that since it is
> running good, that maybe the 40 is not an accurate reading or something.
>
> >  Injector pulse width's were about 7ms when they should be about
> > > 9-11ms at WOT.
> >
> > Oh, and how do you know that they should be those numbers?...  There are
a
> > bunch of considerations about injector sizing, and hence pulse widths.
If
> > ya hunt around the archives some you'll find a injection duration map
for
> a
> > 730 ecm (v-8), and see gm is conservative on injector opening durations.
> > Grumpy
>
> I've got an '85 L98 Vette and when it was all stock, working properly, the
> pulse widths were 10 or 11 at WOT. These are both batch fire setups, even
> though the ECM is different, so I'm guessing again that they should be
> similar in this area.
>
> Shouldn't 'normal' WOT readings for the O2 be in the upper 800's at least?
>
> Craig M.
>
>
>
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