[Diy_efi] O2 Sensor or Computer

[Bruce]

----- Original Message -----
From: "Peter Foote" <pfoote at wightman.ca>
> After that, the block learn values all began to drop
> to 125, which is the min. value I allowed. The O2 sensor was constantly
> reading high and causing the computer to "de-tune" the motor so lean it
> wouldn't run right. It's done this cycle a few times and really has me
> puzzled.

Nothing wrong with even 110s, so long as the car seems about right.   As
long as you in the neighborhood, your fine.   If you want 128s, you'll have
to run Open Loop, but then your tune has to be spot on.

> I have a 1-wire O2 at the collector in the exaust but it does read right
> some of the time so I don't think it needs to be heated.

It's not what you think, it's about what the engine is telling you.

> It's behind ceramic
> coated headers and they seem to really hold the heat in. Also, I had a
meter
> connected to the O2 sensor and it was reading the same high numbers the
> computer was. This makes me think it's the O2 sensor. Anyone ever see an
O2
> sensor ntermittently work?

Yes,
and I've seen that from the exhaust gases being too cold to keep the O2 hot
enough to function.

> Can the computer back drive the O2 sensor?

The O2 is basically a battery that needs heat and oxygen to generate a
voltage.

> Anyone have any partial
> schematics of the O2 input section for that computer? I probably have to
buy
> parts either way and would like to replace the right one.

I'd recommend first finding a 3 wire O2 and trying that.
Bruce
>
> Peter



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