Is It Time For a Tune-up Yet ? Hard Starting, Knocking and Stalling

Hard Starting

This is the most common form of car trouble. It's usually due to some unperformed maintenance.

If the starter cranks the engine, the electrical system probably is ok.  The culprit could be a starting sensor (on fuel injected models) or the choke mechanism (on engines with carburetors).  Frequently, starting failure can be traced to an electronic component or a computer controlling the ignition system.

Knocking

This noise generally is heard when the engine is under load, such as when accelerating or climbing a hill. While it often may be caused by a tankful of inferior gas, ignition knock frequently is a sign your engine needs attention. It also can be caused by a build-up of carbon inside the engine.

Late model cars are equipped with a  knock sensor which "hears" the sound and makes corrective adjustments. But it cannot compensate for a severe malfunction, a condition which can affect engine performance, even damage the engine.

Stalling

This can be caused by incorrect idle speed adjustments, a malfunctioning sensor or switch, dirty fuel system parts, worn spark plugs or other engine deficiencies.  

Does it stall when: 

• Hot? 
• Cold? 
• With air conditioning on? 

To make diagnosis easier, make note of when it happens and advise your technician.