1986 900 Turbo, 16V, 236 k miles, cannot find any leak in turbo plumbing,
noise is in engine compartment, not in car.

I filled up with mid grade and the turbo boost went yet lower. I think the
leak in turbo plumbing is not causing low boost. Leak is 3 years old, low
turbo boost is recent.

With cruise control on, the turbo boost is the same as with it off. So
methinks the computer thinks the cruise control is always on.

Any way to unplug a wire and disable the "feature" that tells the turbo
computer that the cruise control is on?

Thanks,

Charles.