Accord 1985-86 and Prelude 1986-89
1. Remove the oxygen sensor connector.
2. Start the engine and warm it up without load at 3000 rpm, then increase the speed to 4000 rpm and release the throttle pedal sharply. Repeat the procedure at least 5 times.
3. Within one minute after the engine warms up, measure the voltage between the connector terminal and the ground wire, it should correspond to that described in points 4 and 5.
If the measurement procedure takes more than one minute, then repeat the engine warm-up as described in the second point.
4. Increase the engine speed to 5000 rpm, then reduce it to 2000 rpm by pressing the accelerator pedal, immediately turn off the ignition - at this point the voltage should be no more than 0.4 V.
5. Disconnect the vacuum hose between the manifold air pressure sensor and the throttle body from the throttle body and block the hose port in the throttle body. Connect a hand pump to the open end of the hose, create a vacuum of 300 mmHg and increase the engine speed to 4000 rpm. The voltage should be at least 0.6 V.
6. If the voltmeter readings do not match those described, replace the oxygen sensor.
[The original can be found on the resource «www.hondabook.ru»]