1. Defective Coolant Temperature Sensor: As the engine warms up, a faulty coolant temperature sensor may provide incorrect information to the fuel injection system, resulting in improper fuel and air mixture, causing the engine to stall.
2. Faulty Oxygen Sensor: A malfunctioning oxygen sensor may deliver inaccurate data about the fuel mixture, affecting the fuel trim adjustment and contributing to stalling issues when shifting gears.
3. Idle Air Control (IAC) Valve Problems: When dirty or malfunctioning, the IAC valve may not adjust the engine's idle speed precisely, leading to stalling once the engine warms up.
4. Fuel Injector Issues: Clogged or faulty fuel injectors can fail to provide the correct amount of fuel, especially as the engine reaches operating temperature, triggering stalling problems.
5. Weak Fuel Pump: If the fuel pump cannot ensure proper fuel pressure when the engine warms up, it can cause stalling, particularly during gear changes.
Recommendation:
A thorough inspection and diagnosis by a qualified mechanic is highly recommended. Common fixes in such cases often involve cleaning or replacing the mentioned sensors, valves, or fuel system components to get the Pontiac Trans Sport functioning correctly again.
