[WERNER_HAUSSMANN at HP-Loveland-om2.om.hp.com]

Hi James

You are, of course, correct. I was thinking about a throttle body.  I don't 
recommend a running a O2 sensor with a throttle body unless the manifold is 
heated, or is designed for FI.

Also it's worth considering if the engine is meant to run at 
stoichiometric.  I prefer to run it at the mixture that was intended for 
the engine.  Besides running a little rich gives a little more power and 
runs cooler. The problem is fuel condensing out in the manifold and thus 
changing the mixture (with a throttle body). 


And more - some of the '70's cars require a rich mixture for the smog stuff 
to work correctly.  Not all Catalytic converters are '3 -way catalytic 
converters.  Some are not even Catalytic (MGB) I've been told. These 
actually act like an afterburner, and need some fuel (rich) to keep things 
hot.

I suspect the A/F meter you are mentioning for $30 are devices hooked up to 
the O2 sensor.  Anything hooked to a normal O2 sensor can only measure the 
mixture around stoichiometric. It can't measure mixtures that are rich like 
you get with cars designed for carburettors or when you tune for max power.

The CO meter I mentioned is something you stick up the tail pipe.  Not as 
good as the ones at emission testing stations, but a lot cheaper.

Ideally you want to measure the Air, Fuel ratio.  none measure that 
directly.  If you measure the Oxygen (Oxygen sensor) or the Carbon Monoxide 
CO meter (that measures exhaust density) you can infer the A/F mixture.

I think I'm on the DIY EMI list now.  I'll see if this message comes back 
to me.  I still haven't had any replies to my original message.


Werner
Colorado




______________________________ Reply Separator _________________________________
Subject: 
Author:  Non-HP-james (james at brc.ubc.ca) at HP-ColSprings,mimegw2
Date:    3/7/96 2:30 PM



Hello again

What's the theory behind why a O2 sensor won't work in a maifold that has 
been machined to accept injectors just upstream of the intake valve??
Or were you talking about throttle body injection ???
I've seen a couple of conversions (in books) that do this and incorporate 
an O2 sensor...I never thought of this before...interesting.


What about A/F meters...I've seen some people talking about these...they 
a supposedly only $30.00
Ever used one or know what they are talking about???  I don't know 
what these measure  HC, CO or CO2 ???

Ya I'll keep my eye peeled...I'll check out the DIY EFI home page later 
today and see if I can find the instructions I used to subscribe.  See if 
they are any different to what you used.

Say where are you located ?? I'm in Vancouver B.C. Canada.

later and thanks for the ISBN numbers

jw