Engine Tune Up

A tune up is traditionally considered to be a spark plug replacement service, but it can also be called an “Otto cycle optimization and timing service”. The combustion cycle is the series of events that occurs to convert potential energy from fuel in your engine to kinetic energy which powers your vehicle and moves it forward. In regular gasoline engines, it’s called the “Otto” cycle, in diesel engines, it’s called the “diesel” cycle.

Diagram showing the operation of a 4-stroke spark ignition engine. Labels: 1 ‐ Induction, 2 ‐ Compression, 3 ‐ Power, 4 ‐ Exhaust. CC-BY-SA 3.0 Zephyris

The internal combustion engine is a machine that really just contains a series of controlled explosions. These explosions create a lot of pressure that pushes the pistons down; they are choreographed so that while one piston goes down the adjacent piston goes up. Spark plugs ignite that explosion in regular gasoline vehicles. Our article on The Internal Combustion Engine & Engine Oil explains the process in more detail. For quick reference, the Otto Cycle of events includes the following:

• Intake
• Compression
• Combustion (or power)
• Exhaust

In other words, fuel and air are drawn into the engine cylinder by the piston moving down while the intake valve is open. Then the piston starts moving up; both intake and exhaust valves are closed. The piston moving up compresses the air and fuel mixture. Then the air and fuel mixture is ignited with a spark plug (in regular gasoline engines), creating combustion. The extreme heat creates high pressure forcing the piston down. Then the exhaust valve opens. The piston goes back up exhausting the exhaust gas. And then the cycle repeats itself.

The tune-up service is provided to make sure this series of events takes place efficiently. Spark plug firing and the timing of their firing are important aspects that are evaluated and fixed during the service.

When Does My Vehicle Need A Tune-Up?

A tune-up was an annual maintenance requirement for older vehicles. Modern vehicles may not need tune-ups for 100,000 miles. The specific intervals for your vehicle will be listed in the owner’s manual.

If your engine is exhibiting the following symptoms then it may also be time for a tune-up, although that’s something we would verify through an inspection:

• The Check Engine Light is flashing, indicating that there is a misfire (see also Check Engine Light Diagnostic)
• The engine is rough while idling
• Vehicle jerks on acceleration
• Stalling
• Reduced fuel mileage

What Is Included With A Tune-Up?

Tune-ups generally include the following:

• Replacement of spark plugs
• A compression test on the cylinders
• Inspection and/or replacement of ignition wires
• Inspection and/or replacement of distributor cap and rotor
• Adjustment of ignition timing
• Replacement of the fuel filter
• Inspection and/or replacement of the air filter and PCV (positive crankcase ventilation)

Older vehicle tune-ups (for vehicles manufactured prior to 1975) include inspection and/or replacement of ignition points and inspection and/or replacement of the ignition condenser. Then we’d use a dwell meter to set the ignition point gap to obtain a proper dwell reading.

Do Diesel Engines Need A Tune-Up?

One of the major differences between a diesel engine and a regular gasoline engine is that diesel engines don’t have spark plugs, or in other words, spark plugs are not used to ignite the internal combustion in diesel engines.

So do diesel engines need a tune-up? Yes, there are issues that can affect the combustion cycle in diesel engines as well. So just like regular gasoline engines, it’s important to consult the owner’s manual to see the manufacturer’s recommendation and/or bring a diesel engine to the shop for an inspection if it is manifesting any symptoms.

Learn more about Diesel Engine Services.

Call 480-201-0740 To Schedule An Appointment Today

If your vehicle is due for a tune-up according to the mileage or if it is manifesting any symptoms, then bring it to Crawford’s Auto today. We treat your vehicle as if it belonged to our own mother and we never try to sell unnecessary repairs. Call 480-201-0740 to schedule an appointment today.