Component Tests and General Diagnostics

INITIAL TEST DRIVE

Purpose
Tune-ups are generally considered a maintenance procedure. An initial test drive is performed to verify the vehicle is operating properly or to identify any existing driveablity problems. Detailed troubleshooting information is provided in:
Ignition System
Fuel Delivery and Air Induction
Emission Control Systems
Computers and Control Systems

Procedure
- Begin the test drive with a cold engine, this allows you to identify existing warm-up problems.
- While driving the vehicle:
- Accelerate lightly and strongly at both low and high speeds.
- Maintain low and high cruising speeds.
- Decelerate lightly and strongly.
- Allow the vehicle to idle with all accessories operating (this checks for proper idle speed control).
- Allow the vehicle to reach normal operating temperature
- Note any problems and the conditions they occur under.

FINAL TEST DRIVE

Purpose
The final test drive is performed to verify that the vehicle is operating properly and that no driveability problems have occurred as a result of the tune-up.

Procedure
- Drive the vehicle along the same route used for the initial test drive (for comparison purposes).
- Repeat the same driving speeds and engine loads that were used in the initial test.
- If driveability problems were identified during the initial test drive, attempt to repeat the conditions at which the problem occurred.
- After the test drive, inspect the engine for:
- Fuel leaks.
- Ignition cable chafing.
- Forgotten tools.