EGR System Operation
- With transmission in neutral, parking brake on and engine at normal operating temperature, allow engine to idle with throttle closed. Then, quickly accelerate engine to approximately 2, 000 RPM while watching EGR valve stem. Stem should move when engine is accelerated. If not, refer to "Trouble Shooting" in this article.
- Once EGR valve movement has been obtained, it is necessary to determine if EGR is actually taking place. On CCEGR systems, disconnect EGR valve-to-CCEGR valve hose at CCEGR valve. On CTS systems, disconnect hose from EGR valve-to-CTS valve. On all systems, disconnect air cleaner-to-carburetor hose at carburetor.
- With engine idling at normal operating temperature, hold free end of EGR valve hose tightly against opening of carburetor connector (from which air cleaner hose was removed). With hose on connector, engine idle speed should drop about 150 RPM and may stall. This shows that EGR is taking place.
- If speed does not change or change is less than minimum, exhaust deposits are in EGR valve or intake manifold passages. Remove valve for inspection and cleaning. Inspect manifold passages and clean as required.
NOTE:
When cleaning valve, do not allow cleaning solvents on diaphragm. Do not push on diaphragm to operate valve, use vacuum only.