Exhaust Gas Recirculation: Testing and Inspection

EGR Valve:

SYSTEM INSPECTION

NOTE: Check the condition of the wiring harness and/or vacuum lines and connectors before checking the sensors or switches.

1. Start the engine.
2. Accelerate the engine and verify that the diaphragm of the EGR control valve does not move while the engine is still cold.
3. Warm up the engine to normal operating temperature and run it at idle.

WARNING: Be careful when checking the EGR control valve because the surrounding area is very hot.

4. Accelerate the engine and check that the diaphragm of the EGR control valve moves upward.

SOLENOID VALVE (EGR, VENT SIDE)

Fig. 153 Solenoid Vent Side:

1. Disconnect the vacuum hoses.
2. Blow through the vent hose and make sure air flows.
3. Disconnect the solenoid valve connector.
4. Apply 12V and ground the valve as shown.
5. Blow through the vent hose and make sure air does not flow.
6. If not correct, replace the solenoid valves.

SOLENOID VALVE (EGR, VACUUM SIDE)

Fig. 154 Solenoid Vacuum Side:

1. Disconnect the vacuum hoses.
2. Blow through the vacuum hose and make sure air does not flow.
3. Disconnect the solenoid valve connector.
4. Apply 12V and ground the valve as shown.
5. Blow through the vacuum hose and make sure air flows.
6. If not correct, replace the solenoid valves.

EGR Position Sensor Connector Identification:

EGR POSITION SENSOR RESISTANCE INSPECTION

1. Disconnect the EGR position sensor connector.
2. Check resistance between the terminals as shown.

Terminals Resistance

A-B 5 kohms
A-C 0.7-5 kohms
B-C 0.7-5 kohms

EGR CONTROL VALVE

Checking EGR Valve:

1. Manually actuate the valve by pushing on the diaphragm with finger.
2. Check that the spring resistance is present and the diaphragm moves freely with no sticking or binding.

NOTE: Before replacing the EGR control valve, check the intake air and control systems.

Checking EGR Valve Operation:

3. Warm up the engine and run it at idle.
4. Connect a vacuum pump to the valve and apply vacuum.
5. Check that the engine runs roughly or stalls at more than 0-60 mmHg (1.6-2.4 in.Hg).
6. If not correct, replace the EGR control valve.


VACUUM CHAMBER

1. Disconnect the vacuum hoses from the vacuum chamber, and remove it.

Vacuum Pump Connection -- Vacuum Chamber:

2. Connect the vacuum pump to the vacuum chamber as shown.
3. Apply vacuum and check that no vacuum is held.
4. If not correct, replace the vacuum chamber.

Vacuum Pump Connection -- Vacuum Chamber:

5. Connect the vacuum pump to the vacuum chamber as shown.
6. Apply vacuum and check that vacuum is held
7. If not correct, replace the vacuum chamber.