Mechanical Inspection: Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. To check engine compression with a compression gauge, bring engine to normal operating temperature. Disconnect distributor electrical connector(s). Disconnect fuel injector connectors. Remove air intake hose from throttle body. Remove all spark plugs. Fully open throttle. Ensure engine cranking speed is at least 250 RPM when measuring compression.