What’s good, this my first time posting because I have an issue with my G. This morning I had 2 codes pop up, the 171 being bank 1 running lean and the 300 being random multiple missfires detected. My CEL was also blinking.
Only modifications done to my G is an exhaust cutout at the end of the Y pipe. I checked all fluids and hoses and everything was connected, I checked both spark plugs and coil packs and they all checked out. No fuel is leaking from anywhere besides the exhaust cutout.
When idling, she would run at around 1k rpm’s and I could hear a single misfire every couple of minutes. I cleared both codes and closed the cutout and it returned to an idle of around 700rpms.
i don’t really know what the issue is, any input would be greatly appreciated. My only guesses are that there’s not enough backpressure from the cutout or I’m having problems with my injectors?
thank you

 

I got this exact same issue right now and im wanting to see if someone had a solution but no luck. How has yours been since? did you fix it?

 

Have you try to find any air leak ?