People who "tune" their engines by idling and revving them while fiddling under
the hood, hoping to find the right sound, typically have a weak understanding of
engine workings. They think they've got some primal knowledge that "book lernt"
mechanics can't grasp but they're usually grasping at straws. "Duhhh, maybe if I
shake this whatzit and jiggle this hoohaa I can smooth out my idle."
Most of the time they're just dumb white trash, noise-making, sleep-disrupting
idiots. These cretins don't even want to own a modern vehicle that doesn't need
constant (or imagined) fine tuning. You can't justify hours of gratuitous noise
with self-adjusting timing.
It's no coincidence that these same people are always working on their cars
because they never repair them right the first time. Sometimes the problem is
nonexistent and they just want to be seen outside to impress the ladies or
whoever with their mastery of carburetion. "I'm one with my car and you snobs
don't even know what a plenum is!"
Good shade tree mechanics know that idling an engine is one of the worst things
you can do to it, especially at high RPMs when it's cold. Whatever ails the
machine is unlikely to get better by making a lot of racket and going nowhere.
Most neighborhoods have ordinances against this noisy bullshit but they are