Fuel System:
* Fuel pump failure: The fuel pump might be failing to deliver enough fuel to the engine. This could be due to age, wear, or a faulty fuel pump relay.
* Clogged fuel filter: A clogged fuel filter restricts fuel flow, leading to stalling.
* Low fuel: Sounds obvious, but an empty or nearly empty tank can cause problems.
* Fuel injectors: Clogged or malfunctioning fuel injectors prevent proper fuel delivery.
* Fuel pressure regulator: A faulty regulator can cause incorrect fuel pressure.
Ignition System:
* Crankshaft position sensor (CKP): This sensor tells the computer the engine's rotational position. A faulty one will prevent the engine from firing properly.
* Cam position sensor (CMP): Similar to the CKP sensor, a faulty CMP sensor will disrupt timing and cause stalling.
* Ignition coil: A failing ignition coil can't provide the necessary spark to ignite the fuel-air mixture.
* Spark plugs/wires: Worn-out spark plugs or damaged wires can prevent proper ignition.
* Distributor (if applicable): Older vehicles might have distributors; problems here can disrupt the ignition timing.
Other Potential Causes:
* Mass airflow sensor (MAF): A faulty MAF sensor provides incorrect air-fuel mixture information to the engine control unit (ECU), leading to stalling.
* Throttle position sensor (TPS): Similar to the MAF sensor, a faulty TPS can cause incorrect readings, resulting in stalling.
* Idle air control valve (IAC): The IAC controls the idle speed. A malfunctioning IAC can cause stalling, especially at idle.
* Vacuum leaks: Leaks in the vacuum system can disrupt engine performance and lead to stalling.
* Alternator: A failing alternator can't charge the battery, eventually leading to stalling.
* Battery: A weak or dying battery can cause the car to stall.
* Transmission problems (automatic): Issues within the transmission can cause stalling, especially when shifting.
* Computer problems (ECU): In some cases, a faulty ECU can cause various problems, including stalling.
Troubleshooting Steps:
1. Check the obvious: Start with the simplest things: fuel level, battery voltage, and any visible signs of damage.
2. Check engine light: If the check engine light is on, have the codes read at an auto parts store or mechanic. This will give you a starting point.
3. Listen for unusual noises: Pay attention to any unusual sounds from the engine compartment.
4. Inspect for vacuum leaks: Visually inspect vacuum hoses and connections for cracks or leaks.
Important Note: Diagnosing car problems can be complex. If you're not comfortable working on cars yourself, it's best to take your 1998 Chevy Malibu to a qualified mechanic for diagnosis and repair. Attempting complex repairs without the proper knowledge and tools can lead to further damage.
