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 cold start injector (if equipped). Disconnect distributor electrical connector(s). Remove spark plugs. Disconnect air intake hose from throttle body. Fully open throttle. Ensure engine cranking speed is at least 250 RPM when measuring compression.