Techtips: All About Tune-Ups

Find out what to do when your car is sick!

Question:

Answer:

Actually, there's no such thing as a "tune-up" anymore. It's really preventative maintenance and involves changing the spark plugs, air and fuel filters, PCV valve, and checking engine performance.

Webster's Dictionary defines a tune-up as "an adjustment to assure efficient functioning." Back in the early 1970s when many cars still had point ignition systems, checking and adjusting the points and ignition timing every 12,000 to 15,000 miles was usually necessary to compensate for wear. Fiddling with the carburetor idle speed and idle mixture adjustments was also part of the job. Every engine back then also ran on leaded gasoline, which meant the spark plugs rarely lasted more than 12,000 to 15,000 miles before they became fouled with lead deposits. So annual tune-ups were an established ritual. Put off getting one too long and fuel economy, emissions and performance would all suffer. Getting a tune-up usually restored engine performance and was often credited for being a "cure-all" for what ailed your engine. Not so, anymore.

The arrival of electronic ignition systems eliminated wear and the need for any type of periodic adjustment. Once set, ignition timing would remain unchanged unless something failed (in which case the engine usually wouldn't run). "Anti-tamper" carburetors with sealed adjustment screws eliminated the need for most adjustments. The switch to unleaded gasoline stretched plug life to 30,000 miles or more, so the annual "tune-up" became a thing of the past.

Today, virtually everything from idle speed to ignition timing is computer controlled. Since there's nothing left to "tune" in the traditional sense, all that's required is to replace the spark plugs, filters and other wear items periodically to keep the engine in good running condition.

WHAT IS A TUNE-UP TODAY?

The public still associates the word "tune-up" with engine maintenance, so most service facilities continue to use the word in their advertising and promotions. What a "tune-up" actually includes, however, may run the gambit from replacing the spark plugs to a thorough engine diagnosis that also includes scanning the computer system for fault codes, checking engine compression and dozens of other items that may need replacing due to wear. In states where annual emission inspections are required, a tailpipe emissions check may also be included.