I did the smoke test (using a cigar), and did not see any smoke escaping anywhere.

However, I do see that the system does not hold pressure very long (whatever pressure I can manage to apply with my small handpump), is that normal? I assume not as it is supposed to build a vacuum?

The balloon I used to connect myn hand pump's outlet hose to the "Rubber boot with resonator" deflates in about 2 minutes. So, not a quick leak, but definitely not holding. Note that, for this test, I did cap off the small outlet that's on the "tube elbow" that connects to the throttle housing assembly.

I will try the smoke test again when it gets dark as it is easier for me to see the smoke at night.

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2001 BMW X5 3.0i, Automatic, Gasoline