What Does a Tune-Up Include on a Modern Car?

What is a tune-up today? It is the scheduled replacement of the parts an engine still wears out, chiefly the spark plugs, together with a check of the ignition, air and fuel parts around them. Nothing is tuned in the old sense, because a modern engine sets its own ignition timing, fuel mixture and idle speed.

The term has no fixed definition. What it covers differs from one vehicle to the next and from one repair business to the next, and owner’s manuals rarely use the word. They list individual services and the point at which each is due.

If the plugs in your car have reached that point, Golden Star Mobile Mechanics performs tune-ups and spark plug replacement where your vehicle is.

Where the Name Comes From

Older engines needed regular adjustment. Ignition timing, idle speed and the fuel mixture were set by hand, and parts such as breaker points, the distributor cap and the rotor wore out on a routine basis. A tune-up was the visit where that was done, and the engine usually ran noticeably better afterward.

Electronic ignition, fuel injection and computer control removed most of those adjustments. The word stayed in use.

What a Tune-Up Usually Includes Now

Which of these apply depends on the engine and on what the manual says is due.

• Spark plugs. They are the core of the job. Plugs wear as they fire, and the gap the spark has to jump slowly widens.
• Ignition coils, boots or plug wires. These are inspected for cracks, oil and heat damage, and replaced when they show a fault.
• Engine air filter. It is replaced when dirty, and dusty conditions load a filter sooner.
• Fuel filter. It is replaced where the vehicle has one that can be serviced, which many current cars do not.
• PCV valve and hoses. They are checked, and replaced where the manual calls for it.
• A general inspection of belts, hoses, fluid levels, the battery and visible leaks.

The old plugs are worth a look as they come out. Their color and condition can show that a cylinder is running differently from the others, for example because oil or coolant is reaching it.

When It Is Due

Spark plug life varies widely. Plugs with platinum or iridium tips are built to last far longer than the copper plugs older engines used, and the manual gives the interval for the plugs your engine was built with. Hard conditions such as dust, heat and constant short trips can put a car on the manual’s severe-service schedule, which shortens some intervals, the air filter’s in particular.

Leaving plugs in far beyond their interval causes trouble of its own. A wide gap makes the coils work harder, misfires become more likely, and on some engines old plugs can be difficult to remove. Reaching the plugs is simple on some engines and a larger job on others, where intake parts sit over them.

A Tune-Up Is Not a Diagnosis

Drivers often ask for a tune-up because the car has started to run badly: a rough idle, a stumble when accelerating, harder starting or a check engine light. Worn plugs can cause each of those. So can a failing coil, a vacuum leak, a fuel problem or a faulty sensor, and new plugs will not cure them.

When there is a symptom, testing comes before parts. A code scan reads stored codes; a diagnosis goes on to check the ignition, fuel and air systems and tests to confirm the cause. That is the work mobile diagnostics covers.

A check engine light that flashes means the engine is misfiring as you drive. Ease off the throttle and have it looked at soon, because unburned fuel can overheat the catalytic converter.

Questions Worth Asking

Because the word covers so much, ask what is included: which parts will be replaced, which will only be inspected, and how that compares with the schedule in your manual. Replacement plugs should be the type the vehicle manufacturer specifies for the engine.

When the manual says the plugs are due, Golden Star can replace the spark plugs at your vehicle.