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Proj. Cosmo

Nate Bowen

Arturo Chia

Old Updates

"I hope I can lay some of this AF Meter ranting to rest.    I have used
extensively most types and brands of meters out there on the market, as well as
countless hours in the old days (8 years ago) of looking at Haltech mV readings
on the laptop screen. I have used the Autronic system which I am still using
today, the Motec unit, M&W NTK UEGO system.....  UEGO sensors have 5-wires
BTW..... , Autometer cheapie O2 Sensor gauges , the Haltech Haltuner , a few
home-made systems , and probably more than these that I have forgotten about.
This I would say gives me enough experience to know what works and what doesn't.

The true Bosche wide-band sensor equipped systems are more than adequate to use
to tune your car under all operating conditions.  Any system running these
sensors will retail at around US$1000.00 or higher due to the careful
calibration , temperature correction algorithms, and all the rest of the
electronics to read it accurately.  The Bosche wide-band sensor is quite thick
in the body but still fits the standard 18x1.5mm thread, 4-wires going through a
heat-proof jacket, and usually terminated in two plugs that look like injector
clips ... one male one female.
The normal NTK 4-wire sensor that most cheap AF Meter kits will use has a slim
body and same thread size.  It is only of any accuracy when reading 14.0 - 15.5
for A/F ratio.  Even then they are not temperature corrected.   Once you get
below 13.3:1 they become quite erratic in their readings and should not be
relied on. If you are stuck in the middle of nowhere and one of these meters is
your only option , tune wide open throttle so that it never reads less than
full-rich on the scale.  You should normally be aiming for mid to low 12:1 for
less than 10psi , and high 11:1 for above that.
If you are running a single wire sensor I am afraid to say they are quite
useless and you should save up some cash to at the very least run a 4-wire
sensor.

So there you go Eric  , the basics of AF Meters and I think it is OK for you to
use a normal 02 sensor for tuning when nothing else is available.

One other hint for tuning with these devices.  Stoic is only wanted on these
motors if economy and emissions are a concern. If all you want is the best power
and response then you should never come close to running even as lean as 13.8:1
Best power on the 13B is made at 12.7:1 and you will all find this most easily
when tuning idle mixtures. The engine will run at its highest revs when set to
this mixture exactly indicating a higher torque output.  Same happens all
through the load and rev range except under boost where it will need richer to
help prevent detonation.

I hope my little rave here can help a few of you out and maybe end the AF Meter
debate.
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