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 2000 RPM, while watching EGR valve stem. Stem should move when engine is accelerated. If not, refer to TROUBLE SHOOTING .
- Once EGR valve movement has been obtained, verify that EGR is actually taking place. On CVSCC systems, disconnect EGR valve-to-CVSCC valve hose at CVSCC valve. On CTS systems, disconnect hose from EGR valve-to-CTS valve. On either CVSCC or CTS 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 engine 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, inspect and clean valve. Inspect and manifold passages.
NOTE:
When cleaning valve, do not allow solvents on diaphragm. Do not push on diaphragm to operate valve; use vacuum only.