Three weeks ago, my Passat started running really rough. I put the code reader on it and got codes P0304,P0305. Everything I read on the internet pointed to the coilpack. I've since replaced the coilpack, all ignition wires, and all spark plugs. Guess what? Now I have even more codes. Now I have codes P0301,P0303,P0304,P0305,P0306. Why are 5 of 6 cylinders now misfiring?

I have the v6 engine.

I took out the new plugs and new wires. I put the old ones back, so now the only thing new is the coilpack. NO CODES!!

The plugs were Bosch platinum. Would this cause the codes?

either
A- the wires were on incorrectly
b- the poor quality bosch plugs you installed caused the misfire codes

I only put NGK plugs in any car I work on accept gm I put in acdelco

With everything now working correctly, I decided to do an experiment. I pulled out one old plug, and replaced with the Bosch plug. The codes returned! So, new plug out, old plug in.......no code.

I never would have thought the Bosch plug would cause the VW computer to reject it, but it does.

BTW, changing the coil pack was EASY, less than 5 minutes. I couldn't believe it.

bosch makes poor quality everything