See Figures 1, 2 and 3
The EGR system lowers temperatures in the combustion chamber in order to reduce nitrogen oxide emissions in the exhaust gas stream. Exhaust gases are drawn from the cylinder head exhaust port through the intake manifold riser through the cylinder head, intake manifold and EGR valve passages.
1981-95 Gasoline Engines
BACKPRESSURE TRANSDUCER-EXCEPT 3.2L
See Figure 4
This is found on 1.8L, 2.0L and 2.3L carbureted engines.
- Blow air into the black colored hose at the lower side of the transducer. It should be closed.
- Blow air into the EGR side signal hose. Check to see if air passes through the opposite side and air filter side of the transducer.
- If necessary, replace the transducer.
See Figure 5
- Label and disconnect the hoses from the transducer.
- Place a finger over the Vacuum Switching Valve (VSV) port and blow into the EGR valve port of the transducer. Air should pass through the filter portion of the transducer.
- Connect a vacuum gauge to the VSV port and plug the EGR port.
- Blow air into port S . Vacuum should be indicated on the gauge.
- Replace the transducer if necessary.
See Figure 6
This is not used on the fuel injected engines.
The thermal vacuum valve is mounted on the intake manifold and is connected in series between the vacuum port in the carburetor and EGR valve. While the coolant temperature is below 115129°F (4654°C) the valve is closed. Above that temperature, the valve is open.
To test the thermal vacuum valve, disconnect the hoses. Check that no air flows between the hoses when the engine is cold and that the passage opens after engine warms up.EGR CUT VALVE AND DUTY SOLENOID
See Figure 7
These components are only used on the 2.3L and 2.6L fuel injected engines.
- Label and unplug the electrical connection and hoses from the valve/solenoid.
- Apply battery voltage between the terminals using a jumper wire.
- Check that air flows freely from port X to Y .
- Disconnect the jumper wire and check that air does not flow from X to Y .
- Replace the valve/solenoid as necessary.
This component is found on the 2.8L and 3.1L engines.
- Unplug the solenoid valve connector.
- Disconnect the throttle body-to-solenoid valve vacuum hose.
- Apply 15 in. Hg (51 kPa) of vacuum. The solenoid should hold vacuum; if not replace it.
- Apply battery voltage to the solenoid terminals. The vacuum must drop. If not, replace the solenoid valve.
See Figure 8
This component is found on the 3.2L engine.
- Label and unplug the hoses and electrical connection from the valve.
- Check the resistance between the two terminals with an ohmmeter. It should be 33-39 ohms.
- Blow into port 1 . Air should exhaust through the filter, not port 2 .
- Apply battery voltage to the valve terminals. Blow into port 1 . Air should exhaust through port 2 .
- Replace the valve if necessary.
See Figure 9
- Disconnect and plug the vacuum hose from the valve.
- Apply vacuum to the port on the valve. It should hold vacuum.
- Release the vacuum.
- Start the engine and allow it to idle.
- Apply vacuum to the port on the valve. The engine should run rough or stall.
- If the engine did not stall or run rough, shut the engine off and allow it to cool.
- Remove the EGR valve and check for clogged passages in the valve and intake manifold.
- Clean or replace the valve as necessary.
See Figures 10 and 11
An OBD-II compliant scan tool is necessary to diagnose the EGR system used on 1996 models. Please follow the accompanying diagnostic charts.Diesel Engines
An EGR system is used on the C223 California engine only.EGR VALVE
With the engine off, unplug the vacuum hose from the valve. Apply vacuum to the port on the valve. The diaphragm should move smoothly and be able to hold vacuum.VACUUM SWITCHING VALVE
Test the vacuum switching valve by applying 12V to the electrical terminals. Listen for plunger noise that is accompanied with electrical operation of the plunger.CONTROLLER
See Figure 12
To check the controller, connect a voltmeter to the green/black or green (+) and black/yellow (-) wire terminals at the vacuum switching valve. The controller is normal if the voltage is about 12V when the engine speed is below 3000 rpm.THERMAL VACUUM VALVE
Test the thermal valve by submerging it in water and raise the temperature to 115-129°F (46-54°C). Blow through the valve. Air should pass through the valve, if not replace the valve.
REMOVAL & INSTALLATION
See Figure 13
The various control solenoids used on the EGR systems can all be removed using the same basic procedure.
- Unplug the electrical connection from the solenoid.
- Label and disconnect the vacuum hoses.
- Remove any hardware securing the solenoid to the engine.
- When installing the solenoid, be sure to connect the vacuum hoses to the correct ports.
- Label and disconnect the vacuum hoses from the valve.
- Unthread the valve from the intake manifold.
- To install the valve, coat the first few threads with sealer.
- Install the valve in the manifold and tighten until snug. Engage the vacuum hoses.
VACUUM OPERATED VALVES
See Figure 13
- Remove any components which may interfere with removal of the EGR valve.
- Unplug the vacuum hose from the valve.
- If equipped, remove the exhaust crossover pipe from the valve.
- If equipped, bend back the retaining tabs securing the mounting bolts.
- Loosen and remove the bolts securing the valve, then remove the valve.
- Clean the gasket mating surfaces of the manifold and valve.
- Using a new gasket, install the valve. Tighten the bolts until snug.
- If applicable, bend the retaining tabs to secure the mounting bolts.
- Install the crossover pipe if equipped.
- Connect the vacuum hose and install any remaining components removed.
See Figures 14 and 15
These valves are found on 1996 models.
- Disconnect the negative battery cable.
- Unplug the electrical connector from the valve.
- Remove the hardware securing the valve to the intake manifold.
- Remove the valve and gasket from the manifold.
- Install the valve with a new gasket. Tighten the securing hardware until snug.
- Engage the electrical connector to the valve.
- Connect the negative battery cable.