Detonation

POSSIBLE CAUSE ACTION

WITH NO BOOST
Low grade fuel ^ Drain fuel tank and fill with
correct octane fuel

Incorrect valve timing and/or ^ Refer to Engine
clearance for diagnostic procedures

Ignition timing advanced too far ^ Refer to Ignition System/
Adjustments

WITH NORMAL BOOST
Low grade fuel ^ Drain fuel tank and fill with
correct octane fuel

Ignition timing advanced too far ^ Refer to Ignition System/
Adjustments

Insufficient fuel supply ^ Restriction or low fuel pressure,
Refer to Fuel Delivery and Air Induction

EGO sensor malfunction ^ Refer to Computers and Control Systems

Vane airflow meter malfunction ^ Refer to Computers and Control Systems

Engine overheating ^ Service as required

Oil leaking into compressor ^ Refer to Diagnostic Charts-
from turbocharger Pinpoint Tests

Valve seals leaking oil ^ Service as required