1991 bmw 850i timing issue? New to bmw and need help

Hi I have a 91 bmw 850i v12 and it has been sitting for four year. I'm trying to get it running and it has no spark on the left side I replaced the cap and rotors and still no spark , swap cap and rotor side to side still no spark.checked current in all wires and all read the same. Check coil packs for power well turning over the engine both read the same i check power being released from the cap right side has power left side doesn't. I'm am thinking timing but just wanting to make sure before I do a timing chain. And another question will the engine run on one side only working

1991 bmw 850i timing issue? New to bmw and need help