Engine Controls - System/component Tests - 2.3L: Diagnosis Mazda Millenia I

(Using New Generation Star (NGS) Scan Tool)

1. Warm engine to normal operating temperature. Connect NGS scan tool to Data Link Connector (DLC) 2. DLC 2 is located under left side of instrument panel, right of steering column. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD.
2. Turn ignition on. Select HO2S Parameter Identification (PID) to be checked. See HO2S PID IDENTIFICATION table. Voltage should be.5-1.0 volt under acceleration and 0-.5 volt under deceleration. If voltage is not as specified, check wiring harness and connector between ECM and HO2S. Also check intake manifold system, fuel system and self-diagnostic system. Repair as necessary. If no problems are found, replace HO2S.
3. To test HO2S heating element, allow sensor to cool to room temperature. Disconnect HO2S connector. Using ohmmeter, measure resistance between sensor terminals "B" and "C" for front sensor or terminals "C" and "D" for rear sensor. see scheme 8 Resistance should be about 6 ohms with sensor temperature at 68°F (20°C). If resistance is not as specified, replace HO2S.

HO2S PID IDENTIFICATION

Using New Generation Star (NGS) Scan Tool

1. Visually check MAF sensor for cracks or damage. If any damage is present, replace MAF sensor. If no damage is present, turn off all accessories. Connect New Generation Star (NGS) scan tool to Data Link Connector (DLC) 2. DLC 2 is located under left side of instrument panel, right of steering column. Turn ignition on.
2. Using scan tool, select PID/DATA MONITOR AND RECORD function. Select MAF V PID and record value while operating vehicle under specified conditions. See MASS AIRFLOW (MAF) SENSOR VOLTAGE table. If voltage is not as specified, check continuity of each circuit between MAF sensor and ECM/PCM. See appropriate wiring diagram in «WIRING DIAGRAMS - 2.3L»(/mazda/millenia/i-1994-2000/remont/wiring-diagrams-engine-performance/#wiring-diagrams-23l) article. Repair as necessary. If continuity exists in all circuits, replace MAF sensor.

MASS AIRFLOW (MAF) SENSOR VOLTAGE

System Inspection

Purge system operation takes place when vehicle is accelerating in gear (off idle), engine is at operating temperature and oxygen sensor is functioning normally.

Verify that engine coolant temperature is less than 68°F (20°C). Start engine and operate at idle. Remove Positive Crankcase Ventilation (PCV) valve, with hose attached, from valve cover. Block PCV valve opening and check for vacuum. If no vacuum is felt, check for collapsed or blocked PCV valve hose. Repair as necessary. If hose is okay, replace PCV valve.

VACUUM LINE INSPECTION (MILLENIA S)

Remove the clamps and the hose. Apply both suction and pressure to the engine-side of the hose, and verify that air flows only toward that side. (Scheme 33) If air flows in both directions or not at all, replace the vacuum hose.

Scheme 33

VACUUM PUMP INSPECTION (MILLENIA S)

1. Disconnect the vacuum hose from the power brake unit side of the vacuum pump and plug them.
2. Disconnect the vacuum hose from the solenoid valve side of the vacuum pump and connect a vacuum gauge as shown in illustration. (Scheme 34)
3. Under the conditions specified in the «VACUUM PUMP SPECIFICATIONS»(ref-18676-S23958370152004120600000) table, measure the vacuum using a vacuum gauge. If not as specified, replace the pump. VACUUM PUMP SPECIFICATIONS Condition Vacuum In Hg. (KPa) After Running Engine At 900 RPM For 20 Seconds 17.3 (58.7) After Running Engine At 1800 RPM For 20 Seconds 22.8 (77.3)

Scheme 34

See also:
• WIRING DIAGRAMS - 2.3L