Low compression / rough idle - E53 X5 4.6is

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Hi there,

I'm quite new here on this forum - thanks much for any tips, comments or advice in advance.

Timing chain and guides have been replaced on our 2002 X5 4.6is less than 100 miles ago. When starting the car in the morning last week, it had a very rough idle, but engine was running sort of fine at higher rpms. We spent significant time searching for the problem and checked all vacuum hoses connections, sensors, ignition components, etc. but couldn't find a problem. We then checked compression and found that bank 2 (driver side) had low compression in all 4 cylinders. We are suspecting a problem with the variable valve timing system (valves off cycle / not closing completely), since it's quite unusual for all four cylinders on just one side of the engine to have low compression from wear & tear.

Did anyone experience a similar problem in the past and can confirm that a problem with the VANOS system might be causing this?

Any other ideas?

Thanks much in advance.