Re: Re: A/F monitors and the 4.7L mini cats

From: Shane Moseley (smoseley@ix.netcom.com)
Date: Fri Apr 06 2001 - 18:59:13 EDT


Ransom T Holbrook wrote:

> It doesn't matter, before or after..

It does indeed matter. Only the front one is used in the mixture control loop.
The second one is useful only for measuring cat efficiency.

> . ie. Dynojet places a Air/Fuel sensor
> in the tail and gets good readings.

Thats because the one they use is a wide-band model. Those are a whole
different type of sensor. Difference can be well over a thousand dollars (I've
seen some that are over $3000). Furthermore, when using the garden variety O2
sensor - it doesn't become "excited" until it reaches over 600 degrees F. The
closer to the heads - the better when it comes to 1-wire sensors. Ours are the
heated type which helps some but still have to be located relatively close to
the heads. The built-in heater is mostly there to cause the system to be able
to go into closed-loop sooner (and thus reduce emissions sooner). Cold-Start
emissions control is a large part of the OBDII regulations.

Latr,

Shane

ps - isn't this better than all the "How fast is the fastest that you've ever
gone" stuff polluting the list lately?

--
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'74 Triple-Black Dodge Challenger Rallye 360 home-brew EFI R&D vehicle
'68 Black Corvette Convertible 427 (For Sale)



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