Pontiac 1997169 Solenoid Asm,EGR Control Valve Relay

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The system reduces exhaust-emitted nitrogen oxides by recirculating a portion of the exhaust gas. The EGR valve, on the intake manifold, is central to this system. Two EGR valve types exist: negative and positive backpressure. It's inactive at idle and during deceleration, controlled by a thermal vacuum switch. EGR issues can cause rough idling and performance. To inspect, ensure the diaphragm plate moves freely and observe engine speed changes when manually depressed. Examine vacuum lines for blockages. Test the thermal vacuum switch with a gauge, replacing if faulty. For EGR valve replacement, disconnect vacuum hose, remove, and install a new valve with a gasket. For the switch, drain coolant, remove, and install a new one.

The Exhaust Gas Recirculation (EGR) system reduces NOx emissions by reintroducing exhaust gas into the combustion chamber via the EGR valve on the intake manifold. This valve, opened by manifold vacuum, operates primarily during warm engine conditions above idle. The system adjusts gas flow based on manifold vacuum and exhaust backpressure, using a negative backpressure valve. An ECM-controlled solenoid refines EGR flow, receiving input from various sensors. Excessive EGR can cause stalling or surging, while insufficient flow might lead to engine overheating or emission issues. To maintain the system, inspect hoses and connections, ensure EGR valve operation, and check the solenoid. Replace faulty parts and clean the valve and passages when needed.

If the thermal vacuum switch is defective, it should be replaced.

When removing and reinstalling the EGR valve or thermal vacuum switch, it is important to follow the necessary steps. Additionally, a new gasket and thread sealer should be used during reinstallation.

The functioning of the EGR valve can be checked by manually depressing the EGR diaphragm. If the engine loses speed or stalls, it indicates that the valve is working correctly.

With the engine cold to prevent burns, you can reach under the EGR valve and manually push on the diaphragm. Using moderate pressure, you should be able to press the diaphragm up and down within the housing.

If you are unsure about the quality of the valve, you can compare the free movement of your EGR valve with a new valve.

The ECM controlled solenoid is used to maintain finer control of EGR flow.