Engine Diagnosis - 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).

Refer to ENGINE PERFORMANCE DIAGNOSTIC TABLE  and ENGINE MECHANICAL DIAGNOSTIC TABLE  for possible causes and corrections of malfunctions. FUEL SYSTEM - EXCEPT 500E article for the fuel system diagnosis.

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. Refer to CYLINDER COMPRESSION PRESSURE LEAKAGE  .
• Cylinder Combustion Pressure Leakage Test. Refer to CYLINDER COMBUSTION PRESSURE LEAKAGE  .
• Engine Cylinder Head Gasket Failure Diagnosis. Refer to CYLINDER HEAD GASKET  .
• Intake Manifold Leakage Diagnosis. Refer to DIAGNOSIS AND TESTING - INTAKE MANIFOLD LEAKS  .