Car Stalls While Idling
Car is stalling while driving. The stalling occurs when the engine temperature is high or even when the engine temperature is normal.
Idle Air Bypass Valve is Faulty
If your car uses fuel injection system then it has a device called the Idle Bypass Valve. To verify if the bypass valve is the one cause the problem, when the engine is about to stall lightly step on the gas pedal if the car will stay running then the problem is the Idle Bypass Valve. The purpose of the bypass valve is to maintain the idle speed of the engine. If the bypass valve is not working it will cause the engine to stall and by stepping lightly on the gas pedal the throttle will increase which compensate for the faulty bypass valve and giving the engine enough fuel to stay running.
Bring the car to a reputable car shop and ask the mechanic to verify if the Idle Bypass Valve have problem. Just have the valve replaced to fix the problem. Sometimes the mechanic will recommend replacing other items in relation to the Idle Bypass Valve. In this case just stick on the replacement of the bypass valve.
Cold Start Valve Problem
If the car stalling happens only when the engine is cold then the problem is the Cold Start Valve. Fuel injected engine has a components called the Cold Start Valve. The purpose of this valve is to keep the engine running when the engine is cold, by giving extra amount of fuel so that the air/fuel mixture will become rich. Now if this valve has problem then the engine will stall especially when the engine is cold.
Bring the car to a reputable car shop and have a mechanic to check the cold start valve, if the valve is bad then have it replaced.
Faulty Fuel Pressure Regulator
Fuel injection engine also have a component called the Fuel Pressure Regulator. The purpose of this device is to maintain the pressure of every fuel injectors. Now when the regulator has problem it can cause the engine to starve for fuel and it will stall.
Bring the car to a shop and ask the mechanic to verify the fuel pressure regulator. Replace the regulator to fix the problem.