Car trouble symptoms: When the car is idling the engine sounds is not normal than is used to, usually the engine sounds rough.
Diagnosing car engine problems: When your car engine encounter rough idle conditions, this is an indications that the car engine has a problem of misfiring on one or more cylinder. Misfiring cylinder has a weak compression and can cause the engine to become unbalance and sounds rough even at idling. There are several reasons why the car engine cylinder misfires, however determining those reasons can be difficult and need a lot of testing of a qualified mechanic on the actual engine, but the most common causes of engine misfiring are out of adjustments valve, a faulty spark plug wires or spark plug and a vacuum leak. These are only possibilities. In any case the car is needed to be inspected by a mechanic to determine which of the mentioned problems the culprit is.
Possible cause: Bad sparkplug/wires, vacuum leak, or out of adjustments valves.
What to do?
The first thing to do when you want to correct the problem is to consider replacing the spark plug and spark plug wires yourself or have a mechanic to do it if you feel not doing it, usually this can fix the problem. You can buy a replacement parts at any auto parts store just ask the sales person of your required model. However, if the problem still occurs, no other option but to bring your car to a reputable auto repair shop and ask the mechanic to test the engine to determine the exact problem and repair if necessary.