Emission Control System - Evolution Mitsubishi Lancer Evolution VIII

GENERAL DESCRIPTION

The emission control system consists of the following subsystems

1. Positive crankcase ventilation system.
2. Evaporative emission system.
3. Exhaust emission control system.

Scheme 88

Scheme 89

Scheme 90

Scheme 91

VACUUM HOSE INSTALLATION

1. When connecting the vacuum hoses, they should be securely inserted onto the nipples.
2. Connect the hoses correctly, using the (Scheme 90) as a guide.

VACUUM HOSE CHECK

1. Using (Scheme 90) as a guide, check that the vacuum hoses are correctly connected.
2. Check the connection of the vacuum hoses, (removed, loose, etc.) and confirm that there are no sharp bends or damage.

GENERAL DESCRIPTION (POSITIVE CRANKCASE VENTILATION SYSTEM)

The positive crankcase ventilation (PCV) system prevents the escape of blow-by gases from inside the crankcase into the atmosphere.

Fresh air is sent from the air cleaner into the crankcase through the breather hose to be mixed with the blow-by gas inside the crankcase.

The blow-by gas inside the crankcase is drawn into the intake manifold through the PCV valve.

The PCV valve is designed to lift the plunger according to the intake manifold vacuum so as to regulate the flow of blow-by gas properly.

In other words, the blow-by gas flow is regulated during low load engine operation to maintain engine stability, while the flow is increased during high load operation to improve the ventilation performance.

Scheme 92

Scheme 93

Scheme 94

1. Remove the positive crankcase ventilation (PCV) valve from the rocker cover, then reconnect the PCV valve to the vacuum supply hose.
2. With the engine idling, put your finger on the open end of the PCV valve, and check for negative pressure (vacuum). NOTE: At this time, the plunger in the PCV valve should move back and forth as the open end is covered and uncovered.
3. If negative pressure is not felt, clean or replace the PCV valve. Inspect the vacuum supply hose and vacuum supply hose port for restriction or plugged condition.

Scheme 95

1. Hold the positive crankcase ventilation (PCV) valve with the vacuum side down. Insert a thin rod, and using light pressure, depress the end of the PCV valve spring by 5-10 mm (0.2-0.3 inch). Release pressure on the rod to see if the PCV valve spring will lift the rod to its original position.
2. If the rod returns quickly to its original position, the PCV valve is OK. If the stick does not return quickly, clean or replace the PCV valve.

GENERAL DESCRIPTION (EVAPORATIVE EMISSION SYSTEM)

The evaporative emission (EVAP) system prevents fuel vapors generated in the fuel tank from escaping into the atmosphere.

Fuel vapors from the fuel tank flow through the vapor pipe/hose to be stored temporarily in the EVAP canister.

When the vehicle is in operation, fuel vapors stored in the EVAP canister flow the EVAP purge solenoid, purge port and intake manifold plenum to the combustion chamber.

When the engine coolant temperature is low or when the intake air quantity is small (when the engine is at idle, for example), the engine control module (ECM) brings the EVAP purge solenoid into the OFF state to shut off the fuel vapor flow to the intake manifold plenum. This ensures driveability when the engine is cold or running under low load and also stabilizes the emission level.

An EVAP ventilation solenoid is provided between the EVAP canister and atmosphere to monitor for OBD-II EVAP leaks. This solenoid is normally OFF. However, it turns ON when monitoring the OBD-II EVAP leaks and shuts off the atmosphere flow to the EVAP canister. Then the fuel tank differential pressure sensor monitors the fuel vapor pressure to detect OBD-II EVAP leaks. The fuel overflow limiter valve and the leveling valve prevent fuel from being overfilled. The fuel overflow limiter valve and the leveling valve prevent fuel leaks if the vehicle rolls over in an accident.

The EVAP vent valve releases the air from the fuel tank through the EVAP canister into the atmosphere when the fuel tank pressure increases due to refueling, etc. The EVAP vent valve and the air filter supply the atmospheric air to the EVAP canister when the fuel tank pressure decreases.

Scheme 96

Scheme 97

Scheme 98

Required Special Tool

1. MB995061: Purge Flow Indicator

1. Disconnect the purge hose from the evaporative emission (EVAP) purge solenoid, and connect special tool MB995061 between the EVAP purge solenoid and the purge hose.
2. Before inspection and adjustment, set the vehicle in the following conditions: Engine coolant temperature: 80-95°C (176-203°F) Lights, electric cooling fan and accessories: OFF Transaxle: Neutral
3. Run the engine at idle for more than four minutes.
4. Check the purge flow volume when engine is revved suddenly several times. Standard value: Momentarily 20 cm 3 /s (2.5 SCFH) or more.
5. If the purge flow volume is less than the standard value, check it again with the vacuum hose disconnected from the EVAP canister. If the purge flow volume is less than the standard value, check the vacuum port and the vacuum hose for clogging. Also check the EVAP purge solenoid. If the purge flow volume is at the standard value, with the EVAP canister disconnected, replace the EVAP canister.

Scheme 99

Scheme 100

Scheme 101

1. Disconnect the vacuum hose (black, black with red paint mark) from the evaporative emission (EVAP) purge solenoid. NOTE: When disconnecting the vacuum hose, always place an identification mark so that it can be reconnected at its original position.
2. Disconnect the harness connector.
3. Connect a hand vacuum pump to nipple (A) of the EVAP purge solenoid (refer to the illustration (Scheme 99) ).
4. As described in the chart below, check airtightness by applying a vacuum with voltage applied directly from the battery to the EVAP purge solenoid valve and without applying voltage.
5. Measure the resistance between the terminals of the EVAP purge solenoid. Standard value: 30-34 ohms [at 20°C (68°F)]
6. Replace the solenoid if resistance is out of specification.

CHECK VALVE CHECK

Connect a hand vacuum pump to the check valve, apply negative pressure and check the airtightness.

Scheme 102

Scheme 103

VOLUME AIRFLOW SENSOR CHECK

To inspect the sensor, refer to DIAGNOSTIC TROUBLE CODE CHART .

BAROMETRIC PRESSURE SENSOR CHECK

To inspect the sensor, refer to DIAGNOSTIC TROUBLE CODE CHART .

ENGINE COOLANT TEMPERATURE SENSOR CHECK

To inspect the sensor, refer to DIAGNOSTIC TROUBLE CODE CHART .

INTAKE AIR TEMPERATURE SENSOR CHECK

To inspect the sensor, refer to DIAGNOSTIC TROUBLE CODE CHART .

FUEL TANK DIFFERENTIAL PRESSURE SENSOR CHECK

To inspect the sensor, refer to FUEL TANK DIFFERENTIAL PRESSURE SENSOR CHECK .

EVAPORATIVE EMISSION VENTILATION SOLENOID CHECK

Refer to INSPECTION .

GENERAL DESCRIPTION (EXHAUST GAS RECIRCULATION SYSTEM)

The exhaust gas recirculation (EGR) system lowers the nitrogen oxides (NOx) emission level. When the air/fuel mixture combustion temperature is high, a large quantity of NOx is generated in the combustion chamber. Therefore, this system recirculates part of exhaust gas from the exhaust port of the cylinder head to the combustion chamber through the intake manifold to decrease the air/fuel mixture combustion temperature, resulting in reduction of NOx.

The EGR flow rate is controlled by the EGR valve for driveability quality.

OPERATION

When the engine coolant temperature is low, when the engine is at idle or when a wide open throttle operation is performed, the EGR valve is kept closed, achieving no EGR.

After warming up of the engine, the EGR valve can be opened by the engine control module (ECM).

The ECM monitors the EGR system and illuminates the Malfunction Indicator Lamp (SERVICE ENGINE SOON) to indicate that there is a malfunction.

Scheme 104

Scheme 105

Scheme 106

1. Disconnect the vacuum hose (green) from the EGR valve, and then connect a hand vacuum pump via the Tee-fitting.
2. Start the engine. As described in the chart below, check the vacuum condition when the throttle valve is opened suddenly (revving) during cold and hot engine conditions. If the engine is hot and the vacuum does not rise over 13 kPa (3.9 in Hg), perform the vacuum control valve check and EGR port vacuum check. Then continue to Step 3. If vacuum rises momentarily, proceed to Step 3.

When engine is cold

[Engine coolant temperature: 20°C (68°F) or less]

Scheme 107

When engine is hot

[Engine coolant temperature: 80°C (176°F) or more]

Scheme 108

Scheme 109

1. 3. Stop the engine. Remove the Tee-fitting and the hand vacuum pump.
2. 4. Connect the hand vacuum pump directly to the EGR valve.
3. 5. Start the engine and run at idle until warm.
4. 6. The engine idling speed should be rough when a vacuum of 27 kPa (7.9 in Hg) or more is applied to the EGR valve.
5. 7. If engine idles rough, EGR passage is open and the system is OK. If engine idle is not rough, the EGR passage and the valve must be checked for restrictions. Perform the EGR valve check. Then repeat the EGR system check.

Scheme 110

Scheme 111

1. Remove the EGR valve and inspect for sticking, carbon deposits, etc. If necessary, clean with a suitable solvent so that the valve seats correctly.
2. Connect a hand vacuum pump to the EGR valve.
3. Apply 67 kPa (20 in Hg) of vacuum, and check to be sure that the vacuum is maintained.
4. As described in the chart below, apply a vacuum and check the passage of air by blowing through one side of the EGR passage. NOTE: Passage of air should be checked by blowing into the valve port.
5. Reinstall the EGR valve, using a new gasket, and tighten to the specified torque. Tightening torque: 20 +/- 2 N.m (14 +/- 1.4 ft-lb)

Scheme 112

Scheme 113

1. Disconnect the vacuum hose (yellow stripe) from the throttle body EGR vacuum nipple and connect a hand vacuum pump to the nipple.
2. Start the engine.
3. Measure engine vacuum at idle. Standard value: 51 kPa (15 in Hg) or more
4. Reset the vacuum pump to "0" (Release vacuum).
5. Using a stop watch, measure how long it takes for the vacuum gauge to reach 51 kPa (15 in Hg). Standard value: 1.0 second or less
6. If it takes more than 1.0 second for the gauge to reach 51 kPa (15 in Hg), the EGR may be restricted and should be cleaned.

Scheme 114

Scheme 115

Scheme 116

1. Disconnect the vacuum hose from the EGR vacuum regulator solenoid valve. NOTE: When disconnecting the vacuum hose, always make sure that it can be reconnected at its original position.
2. Disconnect the harness connector.
3. Connect a hand vacuum pump to nipple (A) of the EGR vacuum regulator solenoid valve. (Refer to the illustration (Scheme 114).)
4. As described in the chart below, check airtightness by applying a vacuum with voltage applied directly from the battery to the EGR vacuum regulator solenoid valve and without applying voltage.
5. Measure the resistance between the terminals of the EGR vacuum regulator solenoid valve. Standard value: 29 - 35 ohms [at 20°C (68°F)]
6. Replace the EGR vacuum regulator solenoid valve if resistance is out of specification.

To inspect the sensor, refer to DIAGNOSTIC TROUBLE CODE CHART .

To inspect the sensor, refer to DIAGNOSTIC TROUBLE CODE CHART .

CRANKSHAFT POSITION SENSOR CHECK

To inspect the sensor, refer to DIAGNOSTIC TROUBLE CODE CHART .

Scheme 117

<< A >> STRUT TOWER BAR REMOVAL

1. Remove the strut tower bar.
2. After removing the strut tower bar, install the top of the strut assembly temporarily with the strut tower bar mounting nuts.

>> A << STRUT TOWER BAR INSTALLATION

1. Remove the nuts that are temporarily securing the strut assembly.
2. Install the strut tower bar.

Scheme 118

Scheme 119

Scheme 120

Scheme 121

Scheme 122

Scheme 123

1. Blow air through ORVR vent valve module nipple (A). Check that the air flows out of nipple (B) and nipple (C).
2. Connect a hand vacuum pump to nipple (A) of the over vent valve module.
3. With air flow through nipple (C) obstructed, apply a vacuum and check that the vacuum is maintained.
4. Check air tightness by applying a vacuum with voltage applied directly from the battery to the over vent valve module and without applying voltage.
5. Measure the resistance between the terminals of the solenoid. Standard value: 17-21 ohms [at 20°C (68°F)]
6. Replace over vent valve module if resistance is out of specification.

GENERAL DESCRIPTION (CATALYTIC CONVERTER)

The three way catalytic converter, together with the closed loop air-fuel ratio control based on the oxygen sensor signal, oxidizes carbon monoxides (CO) and hydrocarbons (HC), also reduces nitrogen oxides (NOx).

When the mixture is controlled at stoichiometric air-fuel ratio, the three way catalytic converter provides the highest purification against the three constituents, namely, CO, HC and NOx.

Scheme 124

FASTENER TIGHTENING SPECIFICATIONS

Identifying Fastener Tightening Specifications

Scheme 125

See also:
• DIAGNOSTIC TROUBLE CODE CHART
• FUEL TANK DIFFERENTIAL PRESSURE SENSOR CHECK
• INSPECTION