2. When adjusting the idle speed, it is necessary to use a tachometer.
3. Before adjusting the idle speed, check the valve clearances and ignition system (ignition timing, spark plugs) (See Chapters 34, 35, 36 and 37).
4. Warm up the engine to operating temperature and make sure the throttle is fully closed. Disconnect the cooling fan motor connector and turn off all electrical equipment and (if installed) air conditioner. On models with automatic transmission, place the shift lever in the "N" position and apply the parking brake.
5. Start the engine and compare the idle speed with the data given in the Specifications. If adjustment is necessary, turn the idle speed adjustment screw (photo).
The idle speed adjustment screw (arrow) is not easy to reach. Air filter removed for clarity
6. To adjust the idle mixture ratio, an exhaust gas analyzer is required (cO meter). If a gauge is not available, have the mixture adjusted by a Mazda dealer or other qualified person.
7. Install the exhaust gas analyzer and start the engine at idle. Determine the CO content and compare it with the value given in Specifications. If adjustment is necessary, turn the mixture quality adjustment screw (photo).
Turn the idle mixture adjustment screw
8. If the mixture quality adjustment screw is covered by a plug, remove it to gain access to the screw.
9. Once the idle mixture ratio is adjusted, recheck the idle speed and correct it if necessary.
10. Turn off the engine, disconnect the analyzer and reconnect the previously disconnected electrical equipment.