What is a tune up?

Essential Maintenance: The Tune Up Explained

In the past, before electronic ignition systems, a tune-up included new spark plugs, new ignition contact “points,” a new distributor rotor and cap, and a new condenser. In addition, the ignition timing was adjusted using a timing light.

The shop would also clean the carburetor choke and linkage, check the drive belts, check and top off fluids, check/change your air filter, and check your coolant for freeze protection.

What is a tune up now?

There are no points, condensers, rotors or distributor caps in late model vehicles. So a tune usually consists of spark plug replacement along with all the maintenance checks listed below.

1) Inspect spark plug wire or C.O.P. Ignition Coil and Boot condition— Spark plug wires can deteriorate over time and should be checked for signs of arcing and boot deterioration. Coil-on-plug ignition coils degrade from overheating caused by driving with worn-out spark plugs. That heat can cause cracks to form in the coil body and can degrade the boots near the spark plugs.

This image shows the damage from a misfiring coil on plug ignition coil. Notice the arcing on the bottom coil. The spark has been shooting right through the side of the coil above the boot.

2) Serpentine belt wear check— Serpentine belts are now made with EPDM rubber. EPDM doesn’t crack like the older Neoprene belts, but they do wear, and when they wear, they slip. You can’t gauge the wear visually; you need a belt wear gauge. So, inspecting the drive belt is critical to proper engine operation.

3) Check for carbon buildup on the throttle body— All late model engines have an electronic throttle body. Those throttle bodies accumulate carbon deposits that can cause a rough or high idle. During a tune up is the time to inspect the throttle body and clean it when needed. For more information on how to clean a throttle body, see this post.

4) Fluid level and condition test— A good shop will take the time during a tune up to check fluid levels and top off when needed. They’ll also check the condition your coolant and brake fluids using test strips, a refractometer, and a moisture meter.

5) Battery test— A technician can test your car battery’s State of Health in just a few minutes. These modern battery testers are incredibly accurate at determining whether it’s time to replace your battery.

How often do you need a tune up?

That depends on your vehicle’s year, make, model, and engine design. It is NOT true that all late-model cars and trucks only need spark plugs every 100K miles. Late-model engines with turbos can require spark plugs as often as every 45K miles, even if they’re equipped with iridium spark plugs that are “supposed” to last for 100K miles.

Why? Because turbo engines create more combustion pressure and burn a leaner mixture. These lean-burn engines achieve more power with less gas than older engines because they have a turbo to boost combustion pressure. The downside is that the lean burn conditions and extra pressure cause spark plug gap erosion faster than non-turbo and non-learn-burn engines.

WARNING: Not replacing spark plugs on time can cause can result in no-starts, especially in cold weather. Worn spark plugs can also cause misfires that can damage your expensive catalytic converter. Worn spark plug gaps cause ignition coils to work harder, over heat and fail early.

©, 2022 Rick Muscoplat