CORRECT OPERATION

When an engine is in tune, is will operate smoothly and responsively without any abnormal sounds or odors. Signs that an engine needs a tune-up are as follows:

1. Engine is hard to start. It takes several cranks from the starter to get the engine running. This is the most common symptom.
2. Engine knocks or pings. Usually apparent when engine is under load, like accelerating or climbing a hill.
3. Engine diesels or sputters (also known as "run-on" or "after-run"). The engine coughs even after it is shut off.
4. Engine runs rough. This may occur at idle, accelerating, or all the time.
5. Exhaust gas is odorous. It may smell like rotten eggs. This is actually pollution.
6. Engine stalls at various times -- like engine cold, engine hot, air conditioning on, or transmission engaged.
7. Engine has power loss. Particularly evident when climbing hills.
8. Car gets reduced gas mileage. However, this may be caused by non-engine problems, such as poor wheel alignment, underinflated tires, or dragging brakes.

Note that the need for a tune-up can be masked by computer controls that make adjustments to engine performance when it begins to deviate from certain standards. However, the computer cannot compensate for large malfunctions.

SYSTEMS
TUNE-UP
PROPER CARE
VARIATIONS