chris@slowcar.net wrote:
> A simple resistor will not work - the post-cat O2,
> as you surmise, is just there to check that the cat is
> working properly. If the computer doesn't get a reading
> which corresponds properly to the pre cat O2, within
> a certain boundary, it will still set a code
Well, without the cat, the postcat O2 will send the same voltage as the
precat, both fluctuate between .1 and .9 volts, with the postcat hovering
around .4, so we were thinking just a small resistor to reduce the voltage
slightly would do the trick, since the computer wouldn't know any better. Or
would it? Is it constantly comparing O2 sensor fluctuations to make sure one
is following the other? The postcat reads much more stable, normally, cause
of the effect of the cat. Except for mine, which died a few weeks ago.
>
>
> Also the post-cat sensor can have a small effect on A/F
> ratio. As the computer detects the cat degrading it will
> alter the a/f mixture slightly to try and prevent clogging of
> the cat.
Hmm...I was just going by my Haynes manual, which states "The downstream
oxygen sensor (mounted in the exhaust system after the catalytic convertor)
has no effect on PCM control of the air/fuel ratio." Quote.
It goes on the describe the lower O2 content in postcat exhaust, and how it
fluctuates more slowly, blahblahblah. Can the computer throw a code without
tripping the check engine light?
>
> What you really need is an "o2 simulator" - it sounds
> like this is already been covered in the mentioned
> "KatBox" - what I am assuming this is.
>
> Chris Bennight
Yes, the KatBox is perfect, except that it costs over $90...for that much, I
could buy a high-flow cat and take me and my buddies out for beer and pizza
afterwards....*sigh*...ah well, it'll all be moot when I swap in the 360
anyway....
William
97 shortbed standardcab 2wd 2.5l manual, 18.8@75mph, 0.97 inst. g's. beat
that.
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