Rick's Free Auto Repair Advice

What is a tune up?

Tune up — What’s included?

by Rick Muscoplat

In the old days before electronic ignition systems, a tune up included new spark plugs, new contact “points,” a new distributor rotor and cap, and a new condenser. In addition, the ignition system would be timed 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 checks listed above.

How often do you need a tune up?

That depends on the year, make, model and engine design of your vehicle. 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.

Why those checks are even more important now

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.

No choke but now you’ve got carbon buildup in 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.

©, 2022 Rick Muscoplat


Posted on by Rick Muscoplat


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