what causes my Alfa Romeo Giulia 952 (2016-Present) to stall at stoplights?

Symptoms

• Engine stalls unexpectedly at stoplights
• Rough idling before stalling
• Check engine light illuminated
• Difficulty restarting the engine after stalling
• Poor acceleration response when pressing the throttle

Diagnostic Steps

1. Scan for error codes using an OBD-II scanner to identify any related diagnostic trouble codes (DTCs).
2. Inspect the throttle body for carbon buildup or obstructions.
3. Check the fuel pressure with a fuel pressure gauge to ensure it meets manufacturer specifications.
4. Test the idle air control valve (IAC) function to see if it's operating correctly.
5. Inspect the mass airflow sensor (MAF) for dirt or malfunction by cleaning or replacing it if necessary.
6. Examine the vacuum lines for leaks that could affect engine performance.

Solution

1. Preparation

• Gather tools: OBD-II scanner, fuel pressure gauge, socket set, torque wrench, cleaning supplies (throttle body cleaner, MAF cleaner).
• Ensure the vehicle is parked on a flat surface and the engine is cool before beginning work.

2. Check and Clean the Throttle Body

• Step 1: Disconnect the battery to prevent electrical shorts (remove negative terminal).
• Step 2: Remove the air intake duct to access the throttle body (use a socket set).
• Step 3: Clean the throttle body using throttle body cleaner and a soft cloth. Ensure the throttle plate operates freely.
• Step 4: Reassemble air intake duct and reconnect the battery.

3. Test and Clean the Idle Air Control Valve (IAC)

• Step 1: Locate the IAC valve (usually near the throttle body).
• Step 2: Disconnect the electrical connector and remove the IAC valve (use a socket set).
• Step 3: Clean the IAC valve with appropriate cleaner and a brush to remove carbon deposits.
• Step 4: Reinstall the IAC valve and reconnect the electrical connector.

4. Check and Replace Mass Airflow Sensor (if necessary)

• Step 1: Locate the MAF sensor in the air intake system.
• Step 2: Disconnect the electrical connector and remove the MAF sensor (use a socket set).
• Step 3: Clean the MAF sensor with MAF cleaner; if it is still faulty, replace it with a new one.
• Step 4: Reinstall the MAF sensor and reconnect the electrical connector.

5. Check Fuel Pressure

• Step 1: Connect the fuel pressure gauge to the fuel rail.
• Step 2: Turn the ignition to the "ON" position without starting the engine and check if the fuel pressure matches manufacturer specifications (typically around 50-60 psi).
• Step 3: If fuel pressure is low, inspect the fuel pump and fuel filter for blockage or failure and replace as necessary.