(FAST Wideband Air-Fuel
Meter Installation, continued.)
The principle behind tuning with wideband sensors is simple.
By knowing the actual air-fuel ratio of your engine's exhaust,
you can make adjustments to the fuel metering to maximize performance.
Moreover you can dial-in the optimum air-fuel ratio for each
phase of engine operation. At idle and part-throttle you can
tune the engine to run stoichiometric, a lean-best mixture of
fuel-to-air to maximize fuel economy. Likewise, at wide open
throttle you tune for a rich-safe mixture to prevent detonation
and maximize horsepower. Naturally aspirated gasoline engines
make maximum power around air-fuel ratios ranging from 12.5
- 13.3:1, while a richer (safer) mixture is desired for super/turbo
chargers and nitrous.
To feed the signal from the FAST unit to the factory computer
harness we'll modify the narrow-band sensor leads. Clip
the connectors with about 5" of wiring as shown.
You can use some old junyark O2 sensors if you don't want
to hack up a good pair.
Based on the wiring diagram we identified the power, ground
and signal leads on our connectors. Note that the black
leads are actually the narrow-band signal carrying wires.
The 12V source are the white wires (we marked with red
tape.) The other white lead is ground.
We'll take the leads we made up and connect them back
to the factory harness.
Finally, we extended the wires we uncovered from the FAST
harness. Each sensor has a pair of wires; the gray wire
carries the narrow-band signal and the black wire is ground.
Connect them to the respective left and right sensor leads
on the factory harness.
The 12V wires used to heat the factory sensors can be
taped up as the wideband sensors are heated using the
cigarette lighter power adapter. Or you can use the leads
to directly power the FAST unit and ditch the cigarette
lighter adapter.
With everything wired up and the harness cleanly routed,
we're ready to program the unit.
When the unit is powered up you have the option to read
air-fuel or select advanced options. We'll go into advanced
options to configure the unit to send an analog signal
for our narrow-band feed.
The option we'll select is the Narrow Band Simulator.
This will generate a 0-1V signal which the engines computer
will use in open loop mode.
With dual sensors you can configure the screen to display
wide-band air fuel ratio as an average of both sensors
or individually. We prefer individually to get an idea
if both banks are tuned properly.
Finally, the unit will pre-heat the sensors before
it can read the air-fuel ratio.
Once the unit it warmed up it will display the air-fuel
ratio detected by each sensor. The unit is capable of
datalogging up to 25 minutes (50 in single sensor mode.)
Press the up arrow to log, and the down arrow to playback.
As you can see in the video (sidebar) the FAST unit can be wired
in to your ignition so that the unit is activated when the engine
is fired up. The narrow-band sensor output seems to work as
intended. So far we've driven the car over fifty miles without
obtaining a check engine light or noticing any hiccups in performance.
In our opinion the FAST product should be touted for its refinement
and ease of use. The FAST device has a clean blue LED display
and the entire unit is controlled and configured via the built-in
interface. There is no need to connect to a PC as is the case
with most other AF meters. The unit works reliably at every
start. For the average guy simply wanting air-fuel ratios displayed
while he is out tuning without the hassle of a PC, this unit
is fantastic. Those wanting to download the data to their PC
and then chart and crunch numbers with a software tool may not
like the FAST unit's fully-contained simplicity. However, the
analog out lead can be used to wire up a simple serial interface
to a PC. Then one could use Excel or a similar program to visualize
their datalog. That would be a bit to "techy" for
us though.
Posted by Fordota, 04/04/07 12:30pm: I want it! I take it that this digital meter stays in the vehicle...Posted by KenWood, 04/22/07 04:25pm: Pretty hot can you order with the mod's already done?Posted by Dirtyharry, 11/01/07 09:34pm: I bought mine about a year ago and the price has come down fast at the time it was the best choice to pick for dual o2 sensor have used it many times like it alot responds very has helped me to tune my pumpshotPosted by kokkas, 07/27/08 08:52am: I just wish they came with a way to mount it so you don't have to leave it laying around.
When the unit is powered up you have the option to read
air-fuel or select advanced options. We'll go into advanced
options to configure the unit to send an analog signal
for our narrow-band feed.
With dual sensors you can configure the screen to display
wide-band air fuel ratio as an average of both sensors
or individually. We prefer individually to get an idea
if both banks are tuned properly. 
Once the unit it warmed up it will display the air-fuel
ratio detected by each sensor. The unit is capable of
datalogging up to 25 minutes (50 in single sensor mode.)
Press the up arrow to log, and the down arrow to playback.