: CTS 08 3.6 DI "Miss fire cylinder 3" only when cold.

02-26-12, 05:04 PM
I have a 2008 CTS 3.6L DI Premium package. 41,400mi all original parts. It has been running rough on acceleration between 20-45 mph engine light comes on, read code and it says "Miss fire cylinder 3" After it reaches operating temp, it runs fine. Just out of warranty, dealer service says sounds like a coil? I think fouled plug, not sure.
Anyone have directions to change the plugs/coil do you have to remove the manifold for #3 plug?

02-28-12, 04:37 AM
Not difficult at all. I just replaced a coil pack for cylinder #4. You do not need to remove the manifold. I replaced all my plugs at the same time. There are a couple of vacuum lines that will make the job easier if removed.

Good luck!

03-11-12, 11:38 AM
Sorry, Noob here. I understand the firing order but how can the cylinder numbers be determined?

03-11-12, 08:47 PM
Changing the Iridium plugs and running GM fuel system cleaner did the job. You DO NOT have to remove the intake manifold as someone on the internet said. The firing order is 1-3-5 on the drivers side and 2-4-6 on the left.