2006 xc70- 70k miles.
I get the oddest sound when I accelerate...especially on these really hot days. It sounds like pinging, but also like a vacuum leak...sounds like it is coming from the driver's side, almost sounds like it's coming from the vent on the dash by the window. I filled up 2x with high-octane fuel, thinking that if it was engine knock/ ping, that would settle it. Nope.
I looked about the engine area, no loose lines. If I bring it to a mechanic or Volvo, it's money for diagnosis....I want to try to find the problem myself.
Any hints?

A large enough vacuum leak could probably cause pinging that high octane rated fuel can't even suppress.

You may have to get a trusted soul to put the car in gear, hold the brakes tight, and give it some gas to simulate an acceleration load on the engine. Of course you'll want to be standing BESIDE the engine compartment, listening for the noise.

Besides the possibility of a loose turbo/intake hose, you may have an exhaust leak somewhere and that's what you're hearing vs pinging. Maybe.....
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)