Pull the fuel pump fuse and crank the engine a few times to remove any pressure in the fuel system.I have an 05 CTS-V hardly driven (basically sits 77k miles) and started to get flashing check engine light. Pulled code and reads P0300 and after driven awhile it’ll change to P0304. I changed the spark plug and coil in bank 4 and swapped wires. Still no change. My next step is to swap injectors but I am having a hard time finding any “how to” vids or write-ups. Can anyone help me or point out any resources. Any additional help on the codes and misfire also greatly appreciated. Thanks in advance!
Use gloves and rags, you will make a mess.
I highly recommend you replace the fuel injector O-rings after you remove them, and remember to torque the bolts properly.
Alldatadiy is a cheap and awesome resource with step by step guides, I'd suggest getting an account. I think my last renewal was $36 for 3 years or something like that. It's been a while.