6-Cylinder & V8

Deactivate fuel injection system by removing Digital Motor Electronics (DME) master relay and fuel pump relay before performing compression test. See DME & FUEL PUMP RELAY LOCATION table. Ensure battery is fully charged.
Ensure engine coolant temperature does not exceed 86°F (30°C). Remove oil filler cap. Remove 2 nut covers and nuts securing cylinder head cover(s). Remove cylinder head cover(s). Disconnect ignition coil connectors.
Remove ignition coils. Using 16-mm Socket (12-1-171) and Torque Limiter (12-1-172), remove spark plugs. Use Pressure Gauge (11-0-162), Test Adapter (11-0-166) and Tube Extension (11-0-167) to check compression pressure. See COMPRESSION SPECIFICATIONS table.

Fig 1: Locating Fuel Pump Relay (Z3)

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Fig 2: Locating DME & Fuel Pump Relays (318ti)

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 3: Locating DME & Fuel Pump Relays (E36-Except Z3)

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 4: Locating Fuel Pump Relay (E46)

Courtesy of BMW OF NORTH AMERICA, INC.