Mini Countryman intake manifold flap control issue

I have a similar Mini Countryman, though not a diesel. I experienced comparable symptoms a while back: reduced engine performance, rough running, and a hissing sound under acceleration. It sounds like your assessment of the intake manifold flap control issue might be accurate. Have you checked for any engine misfire codes? These are often associated with air intake problems.

Could you elaborate on the engine misfire codes you encountered? Was the hissing sound consistent, or did it vary with engine load? What was the eventual resolution in your case?

Yes, I had similar engine misfire codes. The hissing sound was most pronounced under load, particularly during acceleration. It turned out to be a faulty intake manifold flap. The flap is designed to regulate airflow into the engine, and when it malfunctions, it can cause all sorts of problems with engine performance. I would advise taking it to a workshop to have it properly diagnosed and repaired.

I appreciate you sharing your experience. The diagnostic assessment confirms the intake manifold flap control is indeed defective. Repair completed, cost 465€. Engine performance restored.