B23E Engine W/ Manual Transmission (Canada Only)

Fig. 119 EXHAUST GAS RECIRCULATION SYSTEM (WITH MANUAL TRANSMISSION , CANADA MARKET ONLY):

The exhaust gas recirculation system is used to reduce oxides of nitrogen (NOx) emitted from the engine exhaust. The formation of NOx occur at very high temperatures, during the peak temperature period of the combustion process. To control and reduce the amount of NOx, only a slight reduction in peak combustion temperature is necessary. This reduction is done by introducing small amounts of an inert gas into the combustion process. If too much inert gas is allowed into the combustion process (example stuck E.G.R. valve), the engine will idle roughly or not at all.
The engine exhaust provides a continuous supply of relatively inert gases that can be easily recirculated into the intake manifold. To recirculate these exhaust gases, a connection is made between the exhaust and intake manifolds. Fig. 119.

Fig. 8 EXHAUST GAS RECIRCULATION SYSTEM, WITH THROTTLE CLOSED:

The E.G.R. system consists of a recirculation channel and an E.G.R. valve, which operates on vacuum. Exhaust gas recirculation occurs when the throttle is partly open between the closed (idle) and full throttle position.
When the throttle is closed, Fig. 8, the opening for the E.G.R. hose on the E.G.R. valve is in front of the throttle. The pressure in the E.G.R. valve hose and also in the E.G.R. valve vacuum chamber is equal to atmospheric pressure. Pressure in the E.G.R. valve reference chamber is always equal to atmospheric pressure, the same pressure exists on both sides of the vacuum diaphragm which keeps the valve in a closed position under spring tension.

Fig. 9 EXHAUST GAS RECIRCULATION SYSTEM, WITH THROTTLE PARTIALLY OPEN:

When the throttle is partly open, Fig. 9, the opening for the E.G.R. hose moves behind the throttle. Behind the throttle there is partial vacuum which is transmitted to the vacuum chamber of the E.G.R. valve. The atmospheric pressure in the E.G.R. valve reference chamber forces the diaphragm backward so that the valve opens. Exhaust gas now recirculates to the intake manifold and back into the cylinders for combustion.

Fig. 10 EXHAUST GAS RECIRCULATION SYSTEM, WITH THROTTLE FULLY OPEN:

When the throttle is fully open, Fig. 10, atmospheric pressure in the intake manifold is transmitted to the vacuum chamber of the E.G.R. valve. The pressure on both sides of the diaphragm is now equal which permits the valve to close under spring tension. Exhaust gas recirculation has now stopped.


COMPONENTS:
----------------

Fig. 40 E.G.R. VALVE:

E.G.R. VALVE
The E.G.R. valve is a vacuum activated shut-off and metering valve. It controls the flow of recirculated exhaust gases from the exhaust to the intake manifold. The valve is operated by engine vacuum. Fig. 40.

Fig. 41 THERMOSTAT:

THERMOSTAT
The thermostat allows vacuum to the E.G.R. valve only when the engine is hot. The wax-type thermostat is closed until the engine coolant temperature reaches around 60°C (140°F). Fig. 41.

Fig. 45 E.G.R. REMINDER LIGHT:

E.G.R. REMINDER LIGHT
A reminder light will automatically come on every 15,000 miles (25,000 kilometers) to indicate that the E.G.R. system needs inspection. Fig. 45.