[Dave at Pelican Parts]

The ones that get hooked up to the air cleaner are "seeing" the ambient air pressure--pretty much the same as what is in the engine bay. So no, you don't have to have all of the hoses hooked up. All the ones that connect at or after the throttle body, yes. But the ones that hook to the air cleaner or the rubber boot between it and the throttle body, nope.

Not a good idea to leave them unplugged over the long term, of course, but not a problem for testing.

That's on a 1.7 or a 2.0, with D-jet EFI. This does not apply to the 1.8's L-jetronic FI!! Anything "downstream" of the air flow meter in one of those cars must be plugged in or blocked off!

--DD