Idle Mixture Inspection

WARNING: This page is about a different car, the 2003 Mazda Protege5 and 2003 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.

Perform "Engine Tune-up Preparation".
Verify that the idle speed and ignition timing are within the specification. (See IGNITION TIMING INSPECTION .) (See IDLE SPEED ADJUSTMENT .)
Turn the test mode off.
Warm up the engine by holding the engine speed at 2,500-3,000 rpm for approx. 3 min.
Insert an exhaust gas analyzer to the tailpipe.
Verify that the CO and HC concentrations are within the specified limits.
- If not within the specified limits, inspect the following:
  - On-board diagnostic system (See ON-BOARD DIAGNOSTICS .)
  - HO2S (See HEATED OXYGEN SENSOR .)
  - Intake manifold vacuum . Manifold vacuum should be more that 60 kPa (18 in. Hg) at idle.
  - Fuel line pressure (See FUEL LINE PRESSURE INSPECTION .)
  - Ignition timing control
    - If the systems and devices are normal, replace the TWC. (See EXHAUST SYSTEM REMOVAL/INSTALLATION .)