Air valve (since 1984) (Mazda Capella GC)

The air valve is installed in the bypass hose that bypasses the throttle assembly. It has an electric heating coil and a bimetallic spring. When the engine is cold, the valve is open and allows additional air to flow in to allow the engine to idle. During warm-up, the bimetallic spring gradually closes the valve, thus returning the engine crankshaft to normal idle speed.

Checking the air valve

Start the engine and leave it running in idle mode, then squeeze the bypass hose near the throttle body and make sure that the engine's crankshaft speed has decreased.

If the engine is not warmed up and the crankshaft speed does not decrease, check the tightness of the hoses and the condition of the air valve.

If the engine is warm and the crankshaft speed decreases by more than 200 min⁻¹, disconnect the connector from the valve and remove the rubber boot. With the ignition on, use a voltmeter to check the voltage at the "GR" contact of the connector; it should be equal to the battery voltage. Otherwise, check the corresponding wires and relays.

After disconnecting the connector, use an ohmmeter to measure the resistance between the air valve contacts; it should be within the range of 30–45 Ohms.

Connect the connector.

After disconnecting the two hoses, turn on the ignition and check that the valve is open on a cold engine and closes after the engine warms up.

Turn off the ignition and reinstall the hoses.