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

[rr <RRauscher@nni.com>]

I recall something about this. This ecm does something strange when the
wot tps volts gets higher than 3.8 volts. Try setting the tps sensor to
the lowest voltage.

There is something in the archives about this. Ah, found one of them:

    <Subject: Interesting trivia

    Some time ago Scott S explained some interesting facts about the
    ecm substitiuting values when things go out of parameters.
      Well, got to verify some things today, using a 1227730 BCC AUJP.
    At 3.8v TPS the diacom reads the TPS at 100%.  At high rpm, 10ish
    K/Pa, high TPS (4,80v), commanded AFR was 13.3.  Going to TPS
    4.99v and commanded AFR fell to 15.3.....  Max TPS when AFR
    changed was 4.85v.  If my figures are slightly off to computed
    numbers my equipment is far from lab grade (closer to 4th grade
    school level, hohohahahehe).

      Also, C/L enable temp is 45dC...

    Cheers
    Bruce>

There is another example that was real, guy with a vette was having wot
problems, and the tps change fixed it.

BobR.

Craig Marcho wrote:

> 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!!! Injector pulse width's were about 7ms when they should be about
> 9-11ms at WOT. 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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