The IAC valve regulates the amount of air that bypasses the throttle when the engine is idling. When the engine is cold, the IAC valve opens wider to allow more air to enter and maintain a higher idle speed. If the IAC valve is faulty or dirty, it may not be able to adjust properly, leading to stalling when the car is put into gear.
2. Faulty Temperature Sensor:
The temperature sensor provides the engine control unit (ECU) with information about the engine's temperature. The ECU uses this input to adjust the fuel injection and ignition timing. If the sensor is faulty or sending incorrect readings, the engine may receive an improper fuel mixture or ignition timing, causing it to stall.
3. Fuel System Issues:
Fuel delivery problems can also lead to stalling when the car is cold. This can be due to a faulty fuel injector, fuel pump, fuel pressure regulator, or a clogged fuel filter. If the fuel system is not delivering enough fuel or delivering it at the incorrect pressure, the engine may not be able to maintain combustion and will stall.
4. Vacuum Leaks:
Vacuum leaks can disrupt the air-fuel mixture in the engine, causing it to run rough and stall. A vacuum leak can occur in various places like a cracked hose, a faulty gasket, or a damaged intake manifold. When the engine is cold, the leak becomes more pronounced and leads to stalling when shifted to gear.
5. Faulty Throttle Position Sensor:
The throttle position sensor informs the ECU about the position of the throttle valve. If the sensor is faulty or damaged, it may provide inaccurate information to the ECU, leading to stalls when the transmission is engaged.
6. Battery Issues:
Weak or faulty battery issues can also cause the car to stall while in gear. When the engine is cold, it requires a stronger cranking power to start. If the battery is not providing sufficient power, it can lead to stalling when the car is shifted out of gear.
Since there are multiple possible reasons for this problem, it's important to have your car diagnosed by a professional to identify the exact cause of the stalling and get the appropriate repairs done.
