Buick 17085929 Valve Assembly, Fuel Upper Cnst Control

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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 EGR valve in GM vehicles is found on the intake manifold, near the carburetor or TBI unit. Often, issues in this emissions system are due to a stuck or corroded EGR valve. To check, with a cold engine to avoid burns, manually push the diaphragm under the EGR valve. If it doesn't move easily, replace the valve. If unsure, compare the movement of your valve with a new one.

If the diaphragm of the EGA valve does not move or moves with difficulty, it is recommended to replace the valve with a new one.

The EGR system operates based on throttle position and engine temperature, preventing recirculation during idle, deceleration, or cold starts to maintain the necessary air-fuel mixture.

If the diaphragm does not move or moves only with much effort, it is recommended to replace the EGR valve with a new one.

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.

Common problems associated with the EGR system include rough idling, stalling, and poor engine performance.

The EGR system is used to reduce NOx emissions by lowering combustion temperature.

Most EGR valves are open underneath to check the diaphragm. Using moderate pressure, you should be able to press the diaphragm up and down within the housing.

To check the EGA valve, reach under it with the engine cold and manually push on the diaphragm.

Problems with the EGR system can be addressed through diagnostic tests and component replacements.

If the diaphragm of the EGA valve does not move or moves with difficulty, it is recommended to replace the valve with a new one.