How To Tune Up a Car & What To Replace

The face of the automotive industry is rapidly changing as advancements in technology begin to outmode the old way of doing things. Among the many automotive repairs obsoleted by technology is the popular tune-up. The term sounds catchy enough even if a tune-up sounds like something you might do to a piano. Yet, in today's automobiles, you don't have a lot of variables to adjust. There is no such thing as tuning up a vehicle in the traditional sense of adjusting the ignition timing, shift cables, and throttle cables as they stretch and vibrate loose.

Instead, you will find that a tune-up on today's autos is more of cleaning and basic maintenance job that improves engine performance even if there are no severe problems. There is not a whole lot to adjust on today's automobiles but still a lot to consider.

Tools needed to perform a tune-up

We recommend the following tools:

  • 1/2" Breaker bar

  • 1/2" to 3/8" socket step

  • 12" long socket extension 1/2" or 3/8" drive

  • Spark plug socket

  • Spark plug gap tool

  • Spark plug wire puller tool

  • Coilpack puller tool

  • Torque wrench

  • 1/4" socket set

  • Hose clamps

  • Catch pan

  • Crescent Wrench or line wrench set

  • Large flathead screwdriver

  • Dielectric grease

  • Anti-seize compound

  • Visual inspection

A tune-up should begin with an inspection for leaking fluids, dry-rotted hoses, cracks, frayed belts, corrosion, and various performance problems. Take the vehicle for a test-drive and determine if it’s running sluggish, shaking at idle, whether the throttle and braking are responsive, and if it is shifting properly.

Check the PCV (positive crankcase ventilation) valve and hoses. These items can accumulate a lot of sludge that robs your engine of the air it needs to breathe.

Spark plug replacement

Many manufacturers are fitting vehicles with iridium or platinum-tipped spark plugs that can last up to 100,000 miles under normal operating conditions. This is an inexpensive manner of fulfilling an extensive warranty. The trouble is that these plugs may seize in the engine head if they are never removed and at least inspected every 30,000 miles. Traditional copper plugs are changed at 30,000 miles and arguably offer fuller combustion because the copper is a better conductor.

Removing the spark plugs often requires removal of the engine cover on most late-model vehicles. Although some German vehicles may have various vacuum hoses and components incorporated into the engine cover that complicates removal, most engine covers pop right off when you tug on them.

The trouble comes when you have to remove coil packs or spark plug wires.

Nowadays, manufacturers may have special tools that reduce the tension on the wires themselves. These tools may be necessary to prevent cracking the wire insulation, a condition that leads to misfires.

It’s advisable to temporarily disconnect the negative battery terminal clamp during the tune-up to prevent being maimed by the fan or shocked. Then, soak a penetrating oil like PB Blaster into the spark plug ports before you attempt to turn them loose. Always be sure to apply perpendicular and even pressure when you are turning them with the socket to prevent the ceramic shells from shattering.

When you check the plug, it should look clean. Oil fouled plugs may be a sign that you have problems with your valve stem seals, piston rings, or PCV system. If the tip is eroded, this would be a sign that the spark plug is simply worn out from overuse. Be sure to look for any cracks or damage because this will interfere with proper spark functioning.

You can test whether the spark plug wires are bad by using a multimeter to check the resistance in ohms. Simply, probe both ends and take the reading. The reading should match the factory specifications. Wires that have high internal resistance will generate heat instead of passing electric current onto the spark plugs efficiently.

Before installing the new spark plugs, you should use a spark plug gap tool to check whether the gap is properly set. You can adjust it with a pair of needle-nose pliers if it is too far or too close. Most plugs, however, come with a pre-set gap and require no adjustments.

We recommend that you apply anti-seize compound carefully to the threads to prevent the plugs from seizing. This has minimal effect on the torque settings despite the critics. The torque specs for spark plugs are never a heavy torque because the plugs can shatter or crack like glass under pressure. We also recommend using dielectric grease on the top of the plugs to improve current flow and protect against corrosion.

Air filter replacement

A dirty air filter can rob your vehicle of performance. It usually won’t prevent the vehicle from starting but will create a gradual reduction of throttle response. A dirty air filter can be tested by holding it up to a light and determining how opaque it is. Air filters are easy to replace. In most cases, it is simply a matter of finding the large plastic airbox housing by the battery and loosening the clips to pry the lid loose.

The better plan for a tune-up is to upgrade your air filter with a high-flow filter or cold air intake system. This will add immediate horsepower and throttle response to your vehicle, an excellent low-cost upgrade.

Replace the fuel filter

It may be hard to determine if your fuel filter is restricting fuel flow. It may cause a subtle loss of performance and throttle response when the flow is partially clogged. A filter that is severely clogged will cause your vehicle to sputter, chug, stall, and can even stop it from starting at all. Because most fuel filters are easy to replace and inexpensive, you should plan on replacing the filter every 2 years or 30,000 miles.

On most vehicles, you simply use a crescent or line-wrench to loosen the fuel line fittings on the input and output ports of the filter housing. Once the filter is unfastened from the lines, it’s easy to swap it and install it in a reverse manner. But, always take care to make sure that the fuel flow direction arrow is pointing forward towards the front of the vehicle when you install the new filter to ensure proper flow.

Diesel engines may have two-stage filter systems that require special instructions to replace properly. In either application, you may release pressure from the system by loosening the gas cap or other methods recommended by the manufacturer.

Replacing belts and hoses

Replacing belts and hoses can be easy or complicated. Most belts and hoses can be replaced by amateur mechanics. Timing belt replacements are the exception because they often require extensive skill and experience to pull off correctly. The cost of failure in improperly installing a timing belt may be internal destruction of your engine. If you are temporarily removing any drive belt or serpentine belt, always mark the direction of the original installation to ensure that it seats properly when reinstalled.

If you want to remove hoses easily, you should keep a drain pan under the engine bay to catch the fluids and use hose clamps whenever possible. Using a hose clamp that clamps a coolant hose shut will allow you to remove the band clamp from one end and replace it with a new hose. You can then quickly remove the other end and attach the new hose with minimal fluid losses.

It is important that you only work on the coolant system when the vehicle has not been driven for at least 6 to 8 hours, preferably overnight. If you do not let the engine cool fully, the hot coolant will squirt out under pressure any time that it is cracked open and may cause serious burns.


When it comes time to tune up your vehicle, these are just a few basic things that you can do. There are many other things that may be necessary. Some vehicles today require you to have a computer adaptation of the throttle body whenever you disconnect the battery. This procedure may require you to first clean the throttle body to remove oil and carbon deposits. There are also cleaners and tests for various sensors like the Mass Air Flow Sensor, Mass Absolute Pressure Sensor (MAP), and coolant temperature sensor. They all play a key role in engine performance and are frequently checked.