Begin engine mechanical system diagnosis by reviewing the disassembled views. Reviewing the description and operation information provided will assist in determining whether the condition described by the customer is a fault or normal engine operation.

Strategy Based Diagnosis

1. Review the system operations to familiarize yourself with the system functions.
2. Perform an engine management Diagnostic Systems Check.

All diagnosis on a vehicle should follow a logical process. Strategy based diagnosis is a uniform approach for repairing all vehicle systems. The strategy based diagnostic flow chart may always be used to resolve a system problem. The diagnostic flow chart is the place to start when repairs are required.

Visual/Physical Inspection

1. Inspect the vehicle for aftermarket accessories which may adversely affect engine operation.
2. Inspect the easily accessible or visible system components for obvious signs of damage or conditions that may cause the symptom.
3. Check the engine lubrication system for the following:

•	Correct oil level

•	Correct lubricant viscosity

•	Correct oil filter application and

•	Contaminated or burnt oil

4. Confirm the exact operating conditions under which the fault occurs. Note factors such as:

•	Engine speed (RPM)

•	Ambient temperature

•	Engine temperature

•	Engine warm-up time and

•	Vehicle road speed

5. Compare the engine sounds, if applicable, to a known good engine, and ensure you are not trying to diagnose a normal operating condition.

Intermittent

For intermittent faults, test the vehicle under the same conditions the customer reported in order to confirm whether the system is operating correctly.

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom: