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. |
A good shop manual or the Ford
Fuel Injection & Electronic Engine Control book will
show you the pinouts for the left and right factory O2
sensor harness.
|
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.
