Idle Air Control (IAC) Valve: This valve regulates the air entering the engine at idle. A dirty or malfunctioning IAC valve can cause erratic idling and stalling, especially when coming to a stop.
Throttle Position Sensor (TPS): This sensor tells the computer the position of the throttle. A faulty TPS can give the computer incorrect information, leading to poor idling and stalling.
Mass Air Flow (MAF) Sensor: This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor can cause the engine to run lean or rich, resulting in stalling.
Crankshaft Position Sensor (CKP): This sensor tells the computer the position of the crankshaft. A faulty CKP sensor can prevent the engine from starting or cause it to stall unexpectedly.
PCV Valve: A clogged Positive Crankcase Ventilation (PCV) valve can cause excessive crankcase pressure, affecting engine performance and leading to stalling.
Fuel Delivery Issues: Problems with the fuel pump, fuel filter, or fuel injectors can also cause stalling, especially when the engine's demand for fuel is reduced at idle.
Vacuum Leaks: Leaks in the vacuum lines can disrupt the proper functioning of various engine components, including the brake booster, leading to stalling.
Ignition System Problems: Issues with the ignition coil, spark plugs, or wires can cause misfires and stalling.
Transmission Issues (Automatic): While less likely to be the primary cause of stalling at a stop, a problem with the transmission could contribute, particularly if the car hesitates before stalling.
Battery and Alternator: A weak battery or failing alternator can cause voltage drops, leading to stalling.
What to do:
1. Check Engine Light: Is the Check Engine Light on? If so, have the codes read at an auto parts store (often free) or a mechanic. This will give you a starting point.
2. Visual Inspection: Look for any obvious vacuum leaks, loose wires, or anything out of the ordinary under the hood.
3. Professional Diagnosis: Given the safety implications, it's best to have a qualified mechanic diagnose the problem. They have the tools and expertise to pinpoint the issue accurately. Trying to fix this yourself without proper knowledge could lead to further damage or injury.
Don't continue driving the car extensively with this problem. It's a safety hazard, especially if it stalls unexpectedly while driving.
