I recently had the alternator belt break on my 740GL b230f engine. To my surprise the car continued to run by virtue of my interstate battery. Today I conducted a spark plug and ignition wire replacement as scheduled previously. I have not replaced the belt yet. To my dismay when I started the car after changing the plugs and wires the car is idling very rough as if one of the wires was bad. Until I change the alternator belt it is going to drive me crazy. Could my dead alternator possibly cause this rough idle due to lack of current to the spark plugs? Or did I install plugs wrong, bad wires, etc.? Any ideas would be greatly appreciated.

 

The low voltage usually doesn't make it idle bad.
It is possible but not likely.
Try replacing the new wires one at a time with your old one and see if it gets better.
If not then leave one wire off each cylinder at a time and start it and see if the quality of idle doean't change.
If it doesn't change on one cylinder than the plug migth be bad.

Just because the parts are new doesn't mean they arent bad.