Changed spark plugs, "engine malfunction" now pops up

[MIAblu1]

I changed the plugs yesterday and when I first cranked the motor it sounded like a V8 with cams... turned off the car and turned on again and it was humming normally except a bit louder than usual and it was kicking out smoke from the exhaust. Finally the motor calmed like always and seemed fine. Today I headed to work and all was fine until after work when I headed home and the power wasn't there and the car threw the message of "motor malfunction" and that it was running at reduced power. Went by an auto parts store to check for codes and nothing.... with car on and off. BMW wants $135 just to hook it up to diagnose with their system....
Anyone have this issue? I also don't want to have to pay $135 to be told its a coil pack and then also pay $200+ per coilpack through them if thats the issue.

Yes I got the correct spark plugs before anyone asks... and changed each plug one at a time pulling the coil pack out only for the one I was changing at the time as to not mix anything up or have parts laying around.