Determining 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’s 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.
Changing Your Spark Plugs
How often you replace spark plugs depends on the type of plugs you have. You may have 30,000-mile plugs, or if the plugs have platinum tips, they may be good for up to 100,000 miles, although some professionals recommend replacement every 60,000 miles to avoid damage to the engine. (For detailed information about what spark plugs do, turn to.
However, if they become fouled with oil or become defective, spark plugs may need to be replaced ahead of schedule. There are several ways to tell whether or not the spark plugs on your vehicle need to be changed or just need to be adjusted and replaced. This section tells you how to do that. Of course, before you can evaluate the condition of your spark plugs, you have to find them.
Finding your spark plugs
To locate your spark plugs, look for a set of thick wires (or thin cables) that enter your engine block in neat rows — on both sides if you have a V-type engine or on one side if you have a 4-or 6-cylinder in-line engine (also called a straight engine). These spark-plug wires run from the ignition coil (or the distributor on older vehicles) to the spark plugs.
Deciding if you should do the job yourself
Even if only one of the following conditions is true for your vehicle (and they’re true for most modern vehicles), you should have a professional change your plugs. You don’t want to risk having to replace a really expensive ECU just to save a few dollars on a job that only has to be done infrequently! So don’t be a hero!
plugs until you remove other parts that are in the way. For example, on some transverse engines, you’d have to remove the top engine mount bolts in order to tilt the engine forward to replace the rear spark plugs. And on other engines, you can only get to some spark plugs from underneath or through the wheel well area.
Still, other engines conceal the plugs beneath a metal shield that covers the engine. Removing this shield can require disconnecting cables that can seriously affect the ECU. That’s why the shield is there! Some older domestic engines, most modern import engines, and an increasing number of modern domestic engines have systems that place an ignition coil directly atop each spark plug. There are no spark plug wires, and you can’t see the spark plugs until you remove the aluminum cover that’s bolted to the top of that engine.