Vehicles using M111.977 engine list:

Engine M111.977

Symptoms:
- Rough idling and misfires
- Loss of power and poor acceleration
- Engine hesitation or stalling
- Increased fuel consumption
- Check engine light illumination

Diagnosis:
- Inspect ignition components such as spark plugs, ignition coils, and wires for wear or damage.
- Perform a compression test to check for cylinder sealing issues.
- Scan for fault codes related to sensors like the MAF (Mass Air Flow), oxygen sensors, or crankshaft position sensor.
- Check for vacuum leaks in hoses and intake manifold gaskets.
- Examine the timing chain and tensioner for wear or slack.

Fixes:
- Replace worn or fouled spark plugs and faulty ignition coils.
- Repair or replace damaged vacuum lines and intake gaskets to eliminate leaks.
- Clean or replace the MAF sensor and oxygen sensors if faulty.
- Adjust or replace the timing chain and tensioner if timing issues are detected.
- Perform a fuel system cleaning to restore injector performance.
- Address any detected compression issues, which may require valve or piston ring repairs.

Prevention:
- Follow regular maintenance schedules, including timely spark plug and ignition component replacements.
- Use high-quality fuel and perform periodic fuel system cleaning.
- Regularly inspect and replace air filters to prevent sensor contamination.
- Monitor engine oil condition and change oil at recommended intervals to protect timing chain components.
- Address any engine warning lights promptly to avoid further damage.