Possible reasons why the automatic transmission stalls when stopping:
1. Low transmission fluid level
* Check the gearbox fluid level and top up if necessary.
2. Problems with the crankshaft position sensor
* The crankshaft position sensor transmits engine speed information to the engine control unit (ECU).
*A faulty sensor may send incorrect signals, leading to idle problems.
3. Clogged air flow sensor (MAF)
* The MAF sensor measures the amount of air entering the engine.
* A clogged sensor can cause the air/fuel ratio to be incorrect, causing rough engine idling.
4. Throttle problems
* The throttle valve regulates the air flow into the engine.
* A dirty or faulty throttle body can interfere with proper air flow, causing the engine to drop in idle speed and stall.
5. Malfunction of the fuel pressure regulator
* The fuel pressure regulator maintains constant fuel pressure in the system.
*A faulty regulator can cause fuel pressure to drop, leading to idle problems.
6. Problems with the ECU
* The ECU is the brain of the engine control system.
* A faulty ECU may send incorrect signals to the actuators, resulting in unstable engine idling.
7. Damage to wiring
*Damaged or loose wiring can cause power to sensors or actuators to be interrupted, causing idle problems.
Diagnostics and troubleshooting:
* Read Diagnostic Trouble Codes (DTC) using OBD2 scanner.
* Check the transmission fluid level.
* Inspect the crankshaft position sensor and MAF sensor for dirt or damage.
* Clean or replace the throttle body.
* Check fuel pressure and fuel pressure regulator.
* Diagnose the ECU using a scanner and oscilloscope.
* Check wiring for damage or loose connections.
Important: Always have automatic transmission problems diagnosed and repaired by a qualified mechanic.