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

[Bruce Plecan]

> 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.

 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

The car is bone stock. It runs great, too. What would cause
> this? Is the O2 bad? It seems fine during idle and closed loop operations,
> but just when you hit WOT and the BLM goes to 128, they drop to 40 or so
> until you let off the throttle. TPS voltages seem fine, too.... .55 at
idle,
> and 4.65 at WOT. No codes. Any help is appreciated! If you want the Diacom
> file, I can email it.
> Craig M.


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