Lean Out?

[Neil Swanson <75377.3445@compuserve.com>]

Hey guys,

Someone hac mentioned going to great lengths swapping various parts, injectors
and such to prevent leaning out.

Are you sure you ARE leaning out?

On my Xr and others I know we have been using the Air/Fuel indicator from TWM.
A little black box you can wire into the O2 sensor.  You can add a heated sensor
but on an Xr exhaust gas temp is hot enough at idle, 800 degrees for a reading.
Past 3000rpm on the Xr you switch to open loop and run on the ECU map.  An Audi
may have enough heat already not to need an extra heated sensor.  You need at
least 600 degrees to get the O2 sensor to read.  That is what all my gauges say.
The A/F gauge is dead till my exhaust temp gauge goes to 600+.

Anyway, I assumed that with a big valve ported head, .500+ lift roller cam, free
flow exhaust, more than stock boost, bigger air vane meter etc that I would have
exceeded the fuel flow.  

Not so.  Below 3000rpm the lights indicate the O2 sensor keeping things in the
14.7:1 range.  Over 3000rpm and into open loop I run about 12:1.  Mash the
throttle and the mixture richens up to 10.5-11:1 and settles down to 12:1. This
holds up to 7000rpm and 17lbs boost.  I know people who run more boost and
haven't leaned out. And I know some who found out they do.

I would try one of these meters before going ahead with a bunch of extra fuel.
You may not need it. And too much fuel will hurt power output. I just power mine
of the lighter and run one wire from the O2 sensor.  I attach the box with
velcro when I want a reading.

You can find ads for the TWM meter in Turbo mag, Europian Car and Grass Roots
mag.

Price w/o a heated sensor was $125?  I think.  A friend has one in his tool box
he uses for diagnostic work on stock and none stock cars. 

Neil