Possible reasons why the engine stalls when shifting the automatic transmission:
Problems with the throttle position sensor:
* A faulty throttle position sensor can send incorrect data to the ECU, causing the air/fuel mixture to be adjusted incorrectly.
Clogged throttle valve:
* A clogged throttle valve can prevent air from flowing into the engine, causing it to stall.
Faulty air flow sensor:
* A faulty air flow sensor may not correctly read the amount of air entering the engine, resulting in improper fuel delivery and poor engine performance.
Problems with the crankshaft position sensor:
* A faulty crankshaft position sensor may not correctly sense the crankshaft position, which will result in improper ignition timing and may cause the engine to stall.
Ignition system malfunction:
* A weak spark or incorrect ignition timing can cause unstable engine operation or stalling when the automatic transmission is shifted.
Problems with the fuel supply system:
* The fuel pump, filter or fuel pressure regulator may be faulty, resulting in insufficient fuel pressure and engine stalling.
Mechanical engine problems:
*Low compression, worn pistons or valves can cause the engine to not run properly and stall.
Steps to resolve the issue:
1. Have a mechanic diagnose the problem using error codes.
2. Inspect the throttle body and air filter for blockages.
3. Check the condition of the spark plugs and ignition system wiring.
4. Check the fuel filter and fuel system pressure.
5. Perform an engine compression test to rule out mechanical problems.