8
Installing and Connecting the Air/Fuel Ratio Gauge
Locate the three wires on the back side of the air/fuel ratio gauge. The following
table outlines each of the connections necessary to operate the DFI air/fuel ratio
gauge with the Engine Analyzer series wideband controller.
Wire color
Function
Connect to
Red
Gauge power
Sw12V source
Black
Gauge ground
Main ground source for wideband controller
Gray
Signal input
Gauge output wire on wideband controller
The gauge can be mounted in a 2 1/16” hole or gauge pod. Mounting
hardware is included for panel-mount installations.
It is important to connect the black gauge ground wire to the same grounding
point as the main ground wire for the controller. This is necessary to prevent
ground loops that could cause the gauge reading to be incorrect. The main
ground for the controller is on pin C of the 4-pin connector labeled “0-5V
output” in the wideband controller harness.
Connect the gray wire on the gauge to the gray wire coming from pin 9 on
the wideband controller.
The red power wire should be connected to a sw12V source.
The Accel DFI air/fuel ratio gauge is designed specifically to operate with this
controller. The multi-color LED sweep display around the perimeter of the gauge
face is specially calibrated to provide instant feedback to the driver by changing
colors as the air/fuel ratio range varies. Even if the driver’s attention can’t be
focused on the numbers in the gauge, the color of the LED on the sweep display will
immediately alert the driver if the air/fuel ratio is out of the intended range.
The gauge output from the wideband controller produces a voltage that is equal to
the air/fuel ratio being measured. For example, a 12.8 volt signal means that the
air/fuel ratio is 12.8:1.
If you choose to use a different gauge, you may only use a self-powered digital
voltmeter. Analog voltmeters or gauges will not operate correctly with this
controller.
