GM Service Manual Online
For 1990-2009 cars only
    â€¢ Detonation or spark knock. Check operation of ignition controls or knock sensor circuit.
    â€¢ Loose torque converter bolts.
    â€¢ Exhaust leak at manifold. Tighten the exhaust manifold bolts and/or replace the gasket.
    â€¢ Excessive connecting rod bearing clearance. Replace bearings as necessary.
    â€¢ Excessive piston pin clearance.
    â€¢ Excessive crankshaft thrust bearing clearance.
    â€¢ Bent connecting rod.