Auto Meter 4375 - Manual (Page 3)

Fouling and/or permanent damage to the oxygen sensor over time will
result if used with any of the following:
• Leaded gasoline and fuel additives containing lead
• 2 cycle gasoline (gas/oil mix)
• Diesel Fuel
• Nitromethane
• Excessively rich mixtures
If the Air/Fuel Ratio Monitor responds sluggish, the oxygen sensor is
probably partially fouled and should be replaced.
The Air/Fuel Ratio Monitor has 20 LED’s. Four red that indicate lean,
Ten yellow that indicate stoichiometric ratio, and six that indicate
rich. One LED lights up for every 50mV of oxygen sensor output.
LED Chart
Lean Range Four red LED’s (.050 to .249V)
Stoichiometric Range Ten yellow LED’s (.250 to .749V)
Rich Range Six green LED’s (.750 to 1.000V)
Warning
When the engine is at heavy load the monitor should indicate rich. At
cruising load the monitor will appear to be bouncing back and forth
between rich and lean. This is normal. The computer is constantly
adjusting the air / fuel ratio for performance and low exhaust
emissions. See back page for more detailed information.
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