AmericanMuscle4.6GT

if i decided to go out to my driveway now, disconnect the vaccum line, and let it idle for a minute or so to hear how it sounds, for sheer curiousity purposes, would i harm anything? would my ecu flip out? what are the risks?

hotairgypsy

no but it will not be a pleasant experience...it will probably idol like crap

SCCAGT

Only harm done is a poorly running engine due to it running lean. Check engine light would come on if left unhooked for a period of time. See, unhooking a vaccuum line allows unmetered air to enter the engine. The O2 sensors will see the excess oxygen in the exhaust, and the ECU will try to compensate by dumping in more fuel.

I hope you werent trying to "see how it sounded" as in, how the exhaust sounds. That wont change a bit. It will however sound as though its misfiring if the vaccuum leak is big enough. Nothing to hear by doing this.

AmericanMuscle4.6GT

just want to experience that rough idle, then plug it back in.