Dear Forum Community,

As I have completely reached the limits of my knowledge and no one in my circle of acquaintances can help me further, I am turning to this forum with hope.

My Mini R56, year 2008, 1.6L 122hp gasoline engine runs perfectly fine during a cold start. However, after about 5 km, when the car reaches operating temperature, the problems begin—but ONLY at idle.

The engine still responds to throttle input without issues and performs well, but cylinder one completely drops out at idle (error memory, and the engine continues to run roughly when the ignition coil is disconnected). However, it comes back as soon as the throttle is applied. Additionally, there is an intermittent ticking noise, which I tend to attribute to the hydraulic tappets, though I could be mistaken.

Here’s the strange part: When the car is running extremely rough at idle, if you disconnect either the camshaft sensor or the VANOS control valve, the engine immediately stabilizes and runs very smoothly. I only discovered this by chance recently.

What has been replaced so far: head gasket, timing chain, VANOS exhaust valve, camshaft sensor, ignition coils and spark plugs (swapped around for exclusion testing), ignition cables (checked by an electrician), lambda sensor (a while ago), and components like the thermostat that do not directly affect the engine.

The engine was opened up, and no obvious damage was visible. Another R56 owner experienced similar issues, which were caused by the intermediate lever of the valve in their case. However, their Mini had very poor throttle response and needed to rev out to clear itself, though the VANOS showed a similar phenomenon. Could there be something to this?

I am incredibly grateful for any help!!!

Best regards,
P