DELPHI-Basic-O2-Sensors.ppt

Hondas Air Fuel Sensor When a vehicle travels at a steady cruising speed, it can achieve much better fuel efficiency and better gas mileage with a mixture that is leaner than 14.7:1. Engineers designed an oxygen sensor to take advantage of this better fuel efficiency. One Honda model that uses the Air Fuel (AF) sensor is a lean-burn Civic. The AF sensors design lets it hold the mixture at 14.7:1 during some driving conditions and leaner than 14.7:1 during other conditions. This AF sensor can monitor exhaust O2 levels over a greater range. Its total operating range is from about 14:1 up to 23:1. Air Fuel Sensor Testing - Honda Air Fuel Sensor Testing - Honda Using a DSO Check for any trouble codes. Repair the problem and check to see if a road test resets the code. Connect the positive lead of your scope to second sensor input (the white sensor wire) and the meter ground lead to the sensor ground lead (the black sensor wire, not the vehicle ground). Using a DSO Adjust your scope using these settings: Voltage Scale: 500 millivolts per division Time Base: 200 milliseconds per division Trigger Level: Auto On Put the zero voltage level in the middle of the display. Air Fuel Sensor Testing - Honda Using a DSO Make sure the engine is at normal operating temperature, and the AF sensor is fully warmed up. (2000 RPM for about two minutes) Air Fuel Sensor Testing - Honda Using a DSO Use your propane enrichment tool to richen the engine, and see whether the AF sensor voltage goes negative. Record the average low voltage. Air Fuel Sensor Testing - Honda Zero Volts Rich Mixture Using a DSO Quickly shut off the propane, and force the engine lean. See whether the AF sensor voltage goes positive. Record the average high voltage. Air Fuel Sensor Testing - Honda Zero Volts Lean Mixture Using a DSO Drop the negative sign on the negative voltage, then add the two voltage values together to get the difference between high and low voltages