Alright so i was in town and saw my buddy, when i drove up to say hi he told me to pop my hood so he could show me something. before i know it he had unplugged a sensor with wires leading into it that was located up and to the left of the turbo at the back of the engine bay, against the firewall. he said it was the idm sensor and unplugging it added like 15 horse. now this dude aint that bright when it comes to 7.3s, but still drives one. anyways i go drive around for a bit with it unplugged (dont flame please, i know) and the truck seemed to have a little more power, and dumped WAY more smoke... it also threw a CEL. i shut it off, plugged the sensor back in, and turned the truck back on. cleared the CEL. truck drove4 fine with it plugged in and unpplugged. question is, what is it that the kid actually unplugged, why did the truck respond to it the way it did, and is it really harmful to the engine? thanks in advance!