Fuel System Issues:
* Clogged Fuel Filter: This is a common and relatively inexpensive fix. A clogged filter restricts fuel flow, leading to hesitation, especially under load (when you accelerate).
* Weak Fuel Pump: A failing fuel pump can't deliver sufficient fuel pressure, causing hesitation or even stalling.
* Dirty Fuel Injectors: Clogged injectors can't spray fuel properly, leading to inconsistent fuel delivery and hesitant acceleration. Cleaning or replacing them is often necessary.
* Low Fuel Pressure: This could stem from problems with the fuel pump, regulator, or lines. A pressure gauge test is needed to diagnose this.
Ignition System Issues:
* Worn Spark Plugs or Wires: These are basic tune-up items. Worn plugs misfire, leading to hesitant acceleration. Worn wires can cause similar problems by reducing spark energy.
* Distributor Cap and Rotor: Cracks or corrosion in these components can disrupt the spark delivery to the cylinders.
* Ignition Coil: A failing coil can't provide sufficient spark voltage, resulting in misfires.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position. A faulty CKP can cause misfires and hesitation.
Air Intake System Issues:
* Dirty Air Filter: A severely clogged air filter restricts airflow to the engine, leading to poor performance.
* Vacuum Leaks: Leaks in the vacuum lines can disrupt the engine's air/fuel mixture, causing hesitant acceleration.
Other Potential Issues:
* Throttle Position Sensor (TPS): This sensor tells the computer the throttle's position. A faulty TPS can cause erratic fuel delivery.
* Mass Airflow Sensor (MAF): This sensor measures the amount of air entering the engine. A faulty MAF can lead to incorrect fuel mixture calculations.
* EGR Valve: The Exhaust Gas Recirculation valve helps reduce emissions. A malfunctioning EGR valve can cause rough running and hesitation.
* Computer Issues (PCM/ECM): Though less likely, a problem with the engine's computer could cause these symptoms.
Why a tune-up might NOT fix it:
A tune-up (plugs, wires, cap, rotor, air filter) addresses some of the simpler issues. However, many of the problems listed above, such as a weak fuel pump, clogged injectors, or faulty sensors, won't be solved by a simple tune-up.
What to do:
1. Start with the simple, cheap fixes: Change the air filter, and consider new spark plugs and wires.
2. Check for obvious vacuum leaks: Inspect all vacuum hoses for cracks or loose connections.
3. Consider a professional diagnosis: Take your Cavalier to a reputable mechanic. They can perform diagnostic tests to pinpoint the exact cause of the problem and avoid unnecessary repairs. They may use a scan tool to read diagnostic trouble codes (DTCs) which can help isolate the issue.
A tune-up is a good preventative measure for any car, but it won't magically fix a deeper underlying issue. Proper diagnosis is crucial before spending money on potentially unnecessary repairs.
