Diagnosis and Testing: Introduction

Engine diagnosis is helpful in determining the causes of malfunctions not detected and remedied by routine maintenance.

These malfunctions may be classified as either performance (e.g., engine idles rough and stalls) or mechanical (e.g., a strange noise).

See PERFORMANCE  or MECHANICAL  for possible causes and corrections of malfunctions.

Additional tests and diagnostic procedures may be necessary for specific engine malfunctions that can not be isolated with the Service Diagnosis charts. Information concerning additional tests and diagnosis is provided within the following diagnosis:

• Cylinder Compression Pressure Test. See CYLINDER COMPRESSION PRESSURE LEAKAGE .
• Cylinder Combustion Pressure Leakage Test. See CYLINDER COMBUSTION PRESSURE LEAKAGE .
• Engine Cylinder Head Gasket Failure Diagnosis. See Engine/Cylinder Head - Diagnosis and Testing .
• Intake Manifold Leakage Diagnosis. See Engine/Manifolds/MANIFOLD, Intake - Diagnosis and Testing .