Attach the dwell meter to the diagnostic plug located near the firewall on the engine left side. Reference Service Manual Section M:03:01. The dwell meter positive connection is the upper right corner pin on the diagnostic plug, connect the negative lead of the dwell meter to any engine ground point. Start the car. The dwell meter should read steady with a cold engine. After a couple of minutes the engine should warm and the Oxygen Sensor will begin sending a current to the ECU computer. When the ECU sees this output from the Oxygen Sensor it will begin sending signals to the Frequency Valve to regulate the fuel mixture. The dwell meter should now begin to pulsate in a range of 15-20 degrees. Allow the engine to warm to normal operating temperature (cooling fans come on and cycle off). Set the dwell meter to the four-cylinder range and adjust the CO idle mixture screw to an average reading of 45 degrees. What you are actually reading is the duty cycle of the Frequency Valve. The fact that the dwell meter begins pulsating means the ECU is working. If the ECU fails to work check the ground connections. Run a separate ground wire from the engine block to the ECU mounting bracket ground screw. Redo the ECU test. Reference the Fuel, Emission and Exhaust System section in the repair manual section D:04:14.

Place a jack under the rear frame and raise the rear of the vehicle enough so you can reach into the left-hand wheel well and get at the connector for the oxygen sensor. Pull back the rubber boot covering the connector and expose the connection. (Do Not unplug the sensor at this time) Set your voltmeter on a millivolt (mV) scale and attach the positive lead to the sensor. Attach your negative probe to a suitable ground. Start the car and observe the voltmeter. The voltmeter should rise to between 400 and 600 millivolts as the engine warms up.