how to fix rough idle issue in my Alfa Romeo Giulia 952 (2016-Present) during cold starts?

Symptoms

• Check engine light illuminated
• Engine stalling after initial start
• Unstable RPM fluctuations at idle
• Increased emissions detected
• Poor fuel economy
• Rough engine noise during idle

Diagnostic Steps

1. Scan for error codes using an OBD-II scanner to identify any specific fault codes.
2. Inspect the air intake system for leaks or obstructions that could affect air flow.
3. Check the condition of the spark plugs and ignition coils for wear or damage.
4. Test the fuel pressure to ensure it meets manufacturer specifications.
5. Examine the idle air control valve (IAC) for proper operation and cleanliness.
6. Inspect the coolant temperature sensor for accurate readings.

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plugs

• Remove the engine cover if applicable.
• Use a socket set to remove the ignition coils from the spark plugs.
• Carefully extract the spark plugs using a spark plug socket.
• Inspect the spark plugs for wear, corrosion, or carbon buildup.
• Replace with new spark plugs that meet OEM specifications (refer to the owner's manual for the correct part number).
• Reinstall the ignition coils and engine cover.

3. Clean or Replace the Idle Air Control Valve (IAC)

• Locate the IAC valve, usually found on or near the throttle body.
• Disconnect the electrical connector from the IAC.
• Remove the IAC from its mounting using a socket set.
• Clean the valve with an appropriate throttle body cleaner or replace with a new unit if heavily carbonized.
• Reinstall the IAC and reconnect the electrical connector.

4. Check and Replace the Coolant Temperature Sensor

• Locate the coolant temperature sensor, typically near the thermostat housing.
• Disconnect the electrical connector and remove the sensor using the appropriate socket.
• Install a new coolant temperature sensor, ensuring it is properly torqued as per specifications.
• Reconnect the electrical connector.

5. Inspect Fuel System

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition to the "on" position without starting the engine to check fuel pressure.
• Compare the reading with manufacturer specifications; replace the fuel filter if pressure is low.
• If the fuel pump is defective, replace it according to OEM guidelines.