A tune-up typically includes:
* New spark plugs and wires: Worn or faulty spark plugs and wires are common causes of misfiring.
* New air filter: A clogged air filter restricts airflow, leading to poor combustion and potentially misfires.
* New fuel filter: A clogged fuel filter restricts fuel flow, also affecting combustion.
Other potential causes of skipping that a tune-up *won't* fix:
* Ignition coil(s): These components deliver the high voltage to the spark plugs. A failing coil will cause misfires in the cylinder(s) it controls.
* Distributor cap and rotor (if applicable): Older vehicles use distributors; worn parts here can cause misfires. Your 2000 Expedition might have this, but it's also possible it uses coil-on-plug ignition.
* Mass airflow sensor (MAF sensor): This sensor measures the amount of air entering the engine. A faulty MAF sensor can cause incorrect fuel delivery, leading to misfires.
* Computer issues: The engine control module (ECM) can malfunction and cause misfires.
* Fuel injectors: Clogged or failing injectors can prevent proper fuel delivery.
* Vacuum leaks: Leaks in the intake system can disrupt the air-fuel mixture.
* Low compression: Worn piston rings or valve problems can lead to low compression in one or more cylinders, causing misfires.
Recommendation:
While a tune-up is a good first step in diagnosing a misfiring engine, it's best to get a professional diagnosis. A mechanic can use diagnostic tools to pinpoint the exact cause of the skipping, which may or may not be related to items addressed by a standard tune-up. Simply performing a tune-up without knowing the root cause could be a waste of money if the problem lies elsewhere.
