Base Engine Misfire without Internal Engine Noises

WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Condition	Action
Abnormalities (severe cracking, bumps or missing areas) in the accessory drive belt. Also worn, damaged, or misaligned accessory drive components or excessive pulley runout.	Abnormalities in the accessory drive belt and/or components may cause engine RPM variations, noises similar to a faulty lower engine and also lead to a misfire condition. A misfire code may be present without an actual misfire condition. Inspect the accessory drive components. Repair or replace all damaged components.
Loose and/or damaged crankshaft balancer	A misfire code may be present without an actual misfire condition. Inspect crankshaft balancer and balancer bolt. Repair or replace all damaged components.
Loose torque converter bolts	A misfire code may be present without an actual misfire condition. Inspect torque converter bolts and flywheel. Repair or replace all damaged components.
Loose and/or damaged flywheel	A misfire code may be present without an actual misfire condition. Inspect flywheel and flywheel attaching bolts. Repair or replace all damaged components.
Restricted exhaust system	A severe restriction in the exhaust flow can cause significant loss of engine performance and may set a misfire code. Possible causes of restrictions include collapsed or dented pipes, plugged mufflers and/or catalytic converters. Repair or replace all damaged components.
Air in fuel system	Inspect fuel filter, fuel system for leaks and/or restrictions. Repair or replace all damaged components.
Bent and/or worn valve pushrod	Inspect valve pushrod and valve rocker arm. Repair or replace all damaged components.
Sticking valve	Carbon on the valve stem or valve seat may cause the valve to stick. Inspect valves and valve guides. Repair or replace all damaged components.
Damaged or misaligned timing gears	Inspect timing gears. Replace all damaged components.
Worn or faulty camshaft lobes	Inspect camshaft lobes. If damaged replace camshaft and all lifters.
Excessive piston-to-cylinder bore clearance	Perform cylinder leak down and compression tests. Inspect the piston, piston rings and cylinder bore. Repair or replace all damaged components.
Faulty cylinder head gaskets and/or cracking or other damage to the cylinder heads and engine block cooling system passages. (Coolant consumption may or may not cause the engine to overheat.)	Perform cylinder leak down and compression tests. Inspect the piston, piston rings and cylinder bore. Repair or replace all damaged components.
Overfilled Crankcase	Check engine oil level with vehicle on a level surface. Correct any overfilled condition. Inspect for fuel leaks into the crankcase. Refer to Fuel in Engine Oil . Repair any fuel leaks.