Engine Compression
- 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 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 |
10.0:1 |
| Compression Pressure |
142-156 psi (10-11 kg/cm2
) |
DME & FUEL PUMP RELAY LOCATION
| Application |
Location |
| 318ti |
N/A |
| 318i & 318is |
Behind Cover, Along Engine Compartment Firewall |