Today I noticed that the cruise control on my newly acquired 760 is acting a bit odd.

When going up or down a grade, it holds speed great.

However when just rolling along on a flat section I notice the engine "searching" quite a bit.

It will rev up, and then down, up and down, up and down, the boost gauge also fluctuates from 1/4 to just below 3/4, this happens on about a 3 second interval.

It's quite unnerving as the car also speeds up and slows down in conjunction with this "surging". Say I set my C.C. to 90. the car will fluctuate between 87 and 93. (not that I drive that fast on the motorway mind you, this is just an example ;-)

The motorists in front of and behind me must think I'm a real twit for driving like a obnoxious jerk.

My first assumption is a vacuum leak.... However, I have no service manual (yet) for this vehicle so I'm at your mercy.

When you receive a message from me, and only me, open the attachment.
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john

You're right, it's a vacuum leak.

Good luck finding it.

cheers
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'90 740 Turbo - Hydrogeology Field Vehicle