Detonation (Engine Knock)

WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 1997 BMW Z3, 1997 BMW 840Ci, 1997 BMW 740iL, 1997 BMW 740i, and 1997 BMW 540i. However, it is still accessible from the selected car via links, so may be relevant.

Ignition timing too far advanced.
Blown head gasket.
Stuck thermostat (engine overheating).
Lean fuel mixture.
DME/Motronic control unit malfunction.
No coolant in radiator/engine (engine overheating).
Wrong octane fuel.