it should not affect idle because it should not be spraying at idle. Normally they are set to come on at a certain amount of boost. I guess you could rig something so that it comes on when it sees a certain rpm and WOT.yea. i went out while ago and hooked it up just for shits n giggles. it doesnt really do anything other than possibly help with mileage very slightly. it did seem to idle a little smoother too...could have been my imagination though.