49-State

Flow Diagram:

PURPOSE
- The Exhaust Gas Recirculation (EGR) System is designed to reintroduce exhaust gas into the combustion cycle lowering combustion temperatures and reducing the formation of Oxides of Nitrogen (NOx).


OPERATION
- The amount of exhaust gas reintroduced and the timing of the cycle varies by calibration and is controlled by factors such as engine speed, engine vacuum, coolant temperature and throttle angle. All EGR valves are vacuum actuated. The vacuum diagram is shown on the emission decal for each calibration.

- The EVP EGR Valve is required in EEC systems where EGR flow is controlled by the Powertrain Control Module (PCM) through an EGR Valve Position (EVP) sensor attached to the valve.

- The valve is operated by a vacuum signal from the EGR Electronic Vacuum Regulator (EVR) Solenoid which actuates the valve diaphragm.

- As supply vacuum overcomes the spring load, the diaphragm is actuated. This lifts the pintle off its seat allowing exhaust gas to recirculate (flow). The amount of flow is proportional to the pintle position. The EVP sensor mounted on the valve sends an electrical signal of its position to the PCM.

CONSTRUCTION
The EGR Valve Position System consists of a PCM, EGR Valve, EGR Vacuum Regulator Solenoid, EGR Valve Position Sensor, related wiring and hoses.