"no one" wrote in message ...
Geoff, show me the evidence O2 sensors are primarily for cat performance.

Here is a training document from Toyota. Read the first line of the
document #37- "oxygen and air/ fuel sensors"

http://smccd.net/accounts/sullivank/

If you've ever seen a fi system go into a bad full rich open loop state,
you'll see the cat is REAL efficient. Like white hot efficient.

The problem is with three way converters. Read document #64 from the
same link it will explain the need for tight fuel control on catalytic
converter equipped engines.

Hope this helps.




"Geoff" wrote in message
gy.com...

"lifespeed" wrote in message
om...
"no one" wrote in message
...
Now I got a lot of flak a couple months ago about using O2 sensors in
marine
applications ( a statement was made that O2 sensors are only valuable
for
emissions and catalyst health - which I personally do not agree with
but
am
not in a position to argue)

Comments on closed loop aftermarket MPFI marine applications???

You can do aftermarket SEFI, closed loop with O2 and other cool things
too. Costs money and effort, but it does work, and work well.

What do you mean by "work well"? Is it as good as open loop or measurably
better? Are there noticeable gains in power, torque, startability,
driveability, fuel economy, and/or smoothness? I still maintain that
feedback fuel control exists only to keep a catalyst operating at peak
efficiency. Even closed loop systems go to open loop enriched conditions
under max power situations and/or for the sake of smoothness. I can see
that maybe a closed loop system might be slightly better on gas but if
it's
not controlled well then you're playing with fire. Otherwise I think
you're
adding complexity for minimal gain. If someone wants to experiment. by
all
means go for it - that someone just won't be me.