air-fuel ratio to temp

[David Cooley]

>
>> If you wanted to monitor every cyl, an O2 sensor has almost instantaneous
>> response once it is up to temp.
>
>Interesting.  When I started tuning my supercharged Rx7 I was told (by a
guy who
>builds special test engines for Cartech) that the O2 sensor responds too slow 
>for full throttle high rpm measurements.  He said to use EGT for WOT/maximum 
>boost tuning and suggested a "safe" setting of 1600-1700 F for the rotary.
>
WOW... 1600-1700 is a lot... Maybe he wants to sell you a motor!



>One thing I noticed the other day while blasting up a hill the engine
started to
>detonate, yet the O2 sensor was still reading rich.  I immediately backed off 
>and eased the car up in boost.  Sure enough, the O2 sensor started reading
lean.

Well... Mixture being rich won't keep a motor with too much
advance/compression/hotspots in the combustion chamber from pinging..
The computer did it's job though.. as you back off the gas, it should go lean.
All the guys on the syclone and GN list use O2 sensors to tune and monitor
their runs by.. The ones that have used a EGT have melted pistons before the
thermocouple responded enough to register danger.
Also understand that the O2 sensor isn't linear.. at 14.7:1 A/F, it should
be .45-.5 volts... After that it just means it is richer/leaner than stoich,
but there is no way of knowing exactly how much.
Later,
Dave



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David Cooley                                 Fax: (919) 319-2896       
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