my BMW X3 has a rough idle when starting, what's the issue?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety.
• Allow the engine to cool down before starting work.

2. Inspect and Replace Spark Plugs

1. Remove the engine cover if necessary.
2. Use a socket set to unscrew and remove old spark plugs.
3. Inspect each spark plug for signs of wear or fouling.
4. Install new spark plugs, ensuring they are gapped correctly (typically 0.028-0.032 inches).
5. Torque the spark plugs to the manufacturer’s specifications (usually around 15-20 ft-lbs).

3. Replace Engine Air Filter

1. Locate the air filter housing and remove the screws or clips securing it.
2. Take out the old air filter and inspect the housing for debris.
3. Install a new air filter, ensuring it fits snugly without any gaps.
4. Re-secure the air filter housing.

4. Repair or Replace Vacuum Lines

1. Visually inspect all vacuum lines for cracks, tears, or disconnections.
2. Replace any damaged vacuum lines with new, compatible hoses.
3. Secure all connections to prevent future leaks.

5. Test and Replace Throttle Position Sensor (if needed)

1. Disconnect the electrical connector from the throttle position sensor.
2. Use a multimeter to check the output voltage of the TPS while moving the throttle.
3. If readings are out of specification, replace the TPS with a new unit.
4. Reconnect the electrical connector and ensure it is secure.