uppallnight,

Thanks for the suggestion. My scanner does allow me to check live data. Bank 1 has positive Long Term and negative Short Term. Bank 2 has the opposite. Here are some numbers at idle and 2500 RPM:

Idle
Bank 1 LT: +5.5
Bank 1 ST: 0.0 to -3.0
Bank 2 LT: -0.8
Bank 2 ST: 0.0 to +3.0

2500 RPM
Bank 1 LT: +5.5
Bank 1 ST: 0.0 to -3.0
Bank 2 LT: -0.8
Bank 2 ST: +4.0 to +7.0

What it looks like is that upon going to 2500 RPM, both Short Term trims change, but Bank 1 quickly goes back to the same value as at idle while Bank 2 stays more positive.

From your post, it looks like this is pointing to a vacuum leak. Would appreciate your opinion/direction.

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cmelkoni
2003 X5 3.0i, manual