Engine Compression: 4-Cylinder
- 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. See Figure - Figure
. Ensure battery is fully charged.DME & FUEL PUMP RELAY LOCATION
Application Location 3-Series Z3 DME Relay Right Rear Corner Of Engine Compartment, Next To DME ECU Fuel Pump Relay Under Left Side Of Instrument Panel, Next To Kick Panel E36 DME & Fuel Pump Relays Left Rear Corner Of Engine Compartment, In Relay Box E46 DME Relay Left Rear Corner Of Engine Compartment, In Relay/ECU Box Fuel Pump Relay Behind Glove Box 5-Series & 7-Series DME Relay Right Rear Corner Of Engine Compartment, Next To DME ECU Fuel Pump Relay Right Side Of Trunk 8-Series DME & Fuel Pump Relays Right Rear Corner Of Engine Compartment, Next To DME ECU - Ensure engine coolant temperature does not exceed 95°F (35°C). Turn fasteners (2) on electric lead cover 90 degrees and remove electric lead cover. Disconnect spark plug connectors.
- 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.COMPRESSION SPECIFICATIONS
Application Specification Compression Ratio 4-Cylinder 10.0:1 6-Cylinder 3-Series E36 10.2:1 E46 10.5:1 5-Series 10.2:1 V8 10.0:1 Compression Pressure All Models 142-156 psi (10-11 kg/cm2 )