How to Tell Whether your Vehicle Needs a Tune-up

Tune-up intervals vary from one vehicle to another. Older vehicles with non-electronic ignitions should be tuned every 10,000 to 12,000 miles or every year, whichever comes first. Newer cars with electronic ignition and fuel injection systems are scheduled to go from 25,000 miles to as many as 100,000 miles without needing a major tune-up.
Refer to your owner’s manual for recommended tune-up intervals, but be aware that even if it says that the vehicle doesn’t require scheduled tune-ups very often, it’s in your best interest to check periodically that your vehicle is working at peak efficiency. If you do a lot of stop-and-go driving or pull heavy loads (like a camper or boat), your ignition system may need to be tuned more often. Here are a couple of symptoms that tell you that your electronic ignition system may need to be tuned or adjusted:
The car stalls a lot. The spark plugs may be fouled or worn, the gap between the spark plug electrodes may need adjusting, or an electronic sensing device may need to be adjusted.
If you’re having trouble pinpointing why your vehicle is stalling, you can help your automotive technician diagnose the problem by paying attention to whether the engine stalls when it’s hot or cold or when the air conditioner is on.
The engine is running roughly when idling or when you accelerate. Chances are the vehicle needs a tune-up.
The car gets harder to start. The problem can be in the starting system (for example, a weak battery), in the fuel system (for example, a weak fuel pump), or in the ignition system, or can be due to a faulty electronic component, such as the electronic control unit (ECU).