Knock At Idle, Engine Warm

POSSIBLE CAUSES:
^ Detonation or spark knock. Check operation of ignition controls or knock sensor circuit.
^ Loose torque converter bolts.
^ Exhaust leak at manifold. Tighten the exhaust manifold bolts and/or replace the gasket.
^ Excessive-connecting rod bearing clearance. Replace bearings as necessary.
^ Excessive piston pin clearance.
^ Excessive crankshaft thrust bearing clearance.
^ Bent connecting rod.