Checking Compression
WARNING: This page is about a different car, the 1990 Jaguar XJ-S, 1989 Jaguar XJ-S, 1988 Jaguar XJ-SC, and 1988 Jaguar XJ-S. However, it is still accessible from the selected car via links, so may be relevant.
Check engine compression with engine at normal operating temperature at specified cranking speed with all spark plugs removed (on dual plugs, remove exhaust side only) and throttle valve wide open.