Abnormal Noise Or Knocking

Check engine oil and coolant level.
Check turbo system (if equipped) for damage and wear.
Check engine control system for malfunctioning components. System inspection should include following components: Airflow Meter; Vacuum Routing (For Leaks); EGR Valve Position Sensor (If Equipped); Knock Sensor (If Equipped); Throttle Position Sensor; Coolant Temperature Sensor; Coolant Thermoswitch; Inhibitor Switch (A/T); Electronic Controlled Automatic Transmission (ECAT) Unit