Engine Controls - System & Component Testing: Diagnosis Mazda Millenia I facelift

626 2.0L (Using New Generation Star (NGS) Scan Tool)

1. Warm engine to normal operating temperature. Connect NGS scan tool to Data Link Connector (DLC). DLC 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 FHO2S PID for front sensor or RHO2S PID for rear sensor. See PIN VOLTAGE/PID VALUE CHARTS article. If voltage is not as specified, check wiring harness between PCM 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 terminals "B" and "C" for 3-terminal sensor or "C" and "D" for 4-terminal sensor. see scheme 18 Resistance should be about 6 ohms at 68°F (20° C). If resistance is not as specified, replace HO2S.

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. Ensure all vapor lines are connected and in acceptable condition. (Scheme 50), (Scheme 51) or (Scheme 52).

Note. Evaporative emission system schematic for 626 is not available from manufacturer.

Scheme 50

Scheme 51

Scheme 52

Purge system operation takes place when vehicle is accelerating in gear (off idle), engine is at operating temperature and oxygen sensor is functioning normally. Ensure all vapor lines are connected and in acceptable condition. (Scheme 53)

Scheme 53

EVAP System Test

Note. This can be used as an alternative to Drive mode 4.

Scheme 54

Scheme 55

1. Connect scan tool. Select startup. Select metric. Check PIDs. Ensure BARO (72.2 kPa or more), ECT (-7.5-70°C), FLT V (1.1-3.0 volts) and IAT (0-60°C) are as specified. Ensure IAT and ECT are within 10°C.
2. Start engine. Run engine at 3500 RPM for 3.5 minutes. Select DIAGNOSTIC SUPPORT PROCEDURE, SINGLE TEST, EVAP LEAK TEST. Press trigger. Engine spped should raise to 2000 RPM. After one minute, depress accelerator to end test. Check and record FTP1SV and FTP2SV PIDs. Check FTP1SV PID value. (Scheme 54) If PID is okay, go to next step. If PID is not within specification, a large leak is present. See DTC P0455.
3. Subtract FTP1SV from FTP2SV. Check specification. (Scheme 55) If specification is okay, test is complete. If specification is not within specification, a small leak is present. See DTC P0442.

Whole System Test

Note. Test must be performed within 10 minutes and without starting engine. Do not exceed 6.4 kPa pressure in EVAP system.

Disconnect vacuum hose from catch tank to purge solenoid valve at valve. Connect hose to vacuum pump. Connect scan tool. Select ON BOARD DEVICE CONTROL. Return to scan tool main menu and select PID monitor. Select FTP PID. Apply 1.7 kPa vacuum. Vacuum should hold for at least two minutes. If vacuum does not hold, check FTP sensor. Replace as necessary. If sensor is okay, replace hose and go to CHARCOAL CANISTER-TO-PURGE SOLENOID TEST .

Charcoal Canister-To-Purge Solenoid Test

Note. Test must be performed within 10 minutes and without starting engine. Do not exceed 6.4 kPa pressure in EVAP system.

Check hose condition and routing between charcoal canister and purge solenoid valve. Repair as necessary. Disconnect vacuum hose from fuel tank to charcoal canister at canister. Connect hose to vacuum pump. Connect scan tool. Select ON BOARD DEVICE CONTROL. Return to scan tool main menu and select PID monitor. Select FTP PID. Apply 1.7 kPa vacuum. Vacuum should hold for at least two minutes. If vacuum does not hold, check FTP sensor, purge solenoid valve, catch tank charcoal canister, CDCV and connecting hoses. Repair or replace as necessary. If vacuum holds, reconnect hose and go to CHARCOAL CANISTER-TO-FUEL TANK TEST .

Charcoal Canister-To-Fuel Tank Test

Note. Test must be performed within 10 minutes and without starting engine. Do not exceed 6.4 kPa pressure in EVAP system.

Check hose condition and routing between charcoal canister and fuel tank. Repair as necessary. Disconnect vacuum hose from catch tank to charcoal canister at canister. Connect hose to vacuum pump. Connect scan tool. Select ON BOARD DEVICE CONTROL. Return to scan tool main menu and select PID monitor. Select FTP PID. Apply 1.7 kPa vacuum. Vacuum should hold for at least two minutes. If vacuum does not hold, check fuel filler cap, fuel filler pipe, fuel tank and connecting hoses. Repair or replace as necessary.

Purge Control Test

1. Start engine. Disconnect vacuum hose from catch tank to purge solenoid valve at valve. Check that there is no vacuum at valve fitting when engine is cold. If no vacuum is present, go to next step. If vacuum is present, check purge solenoid valve and wiring. Repair as necessary.
2. Warm engine to operating temperature. Turn ignition off. Connect scan tool. Turn ignition on. Select ECT PID. If ECT PID is more than 140°F (60°C), go to next step. If ECT PID is 140°F (60°C) or less, check ECT sensor. Repair as necessary.
3. Select SIMULATION TEST and PRG V PID. Press start. Using scan tool, increase purge solenoid valve duty cycle to 50 per cent. If valve operation is heard, check vacuum hoses. If valve operation is not heard, check purge solenoid valve. Repair as necessary.

System Inspection (Except MPV)

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.

System Inspection (MPV)

Start engine and operate at idle. Remove Positive Crankcase Ventilation (PCV) valve from breater hose, located under inlet hose. 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 56) If air flows in both directions or not at all, replace the vacuum hose.

Scheme 56

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 57)
3. Under the conditions specified in the «VACUUM PUMP SPECIFICATIONS»(ref-2849-S24744500782004120600000) 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 57