I have a V8 and I changed 4 of the plugs on Friday and didn't get around to finishing the rest. The car drove fine on Saturday. On Sunday the car seemed to misfire a little. More of a rough idle. On Sunday evening I changed the other 4 plugs. When I turned the car on the car idled roughly and the check engine light came on. I am lost now. I made sure I connected everything back and didn't disconnect anything else. Everything seems fine. I put BOSCH plugs in the car. I took four of the BOSCH out and put the 4 of the originals back in to see if that made a difference and it didn't. Any ideas??? I do not want to take the car to a mechanic. Much help is appreciated!!!!!!!! It is a V8 LS.