Q: What is the location of the EGR valve on Chevrolet Caprice and what is the common cause of faults in this emissions system?
A: The EGR Valve on GM vehicles is located on the intake manifold, by the Carburetor. Most times, when a fault occurs in this emissions system it is caused by a stuck or corroded EGR valve. With the engine cold to prevent burns, reach under the EGR valve and manually push on the diaphragm. You should be able to press the diaphragm up and down within the housing using moderate pressure. If it does not or needs too much effort to move, then replace it with a new EGR valve. If you are unsure of its quality, visit your local parts store and compare the free movement of your EGR valve with a new one. The sixth part has more information about further testing of the EGR system and component replacement procedures.
Q: What is the purpose and operation of the EGR Vacuum Solenoid and EGR Valve on Chevrolet Caprice?
A: 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.