Quote:
Originally Posted by EMTNLSS
Yep I have this exact same issue. Codes P050D and P0300. I've logged it with hptuners and it's misfiring in cylinder 7 and 8 for me only during the cold start sequence. Like you said as soon as the rpms drop to around 700 I get no misfires. I can drive it around and hptuners shows no misfires. I bought some new injectors and will be replacing them as I believe that's the issue. During a cold start the injectors run in a special mode that pulses them twice or something like that and in hptuners I can watch them switch off that mode. As soon as that happens the misfires stop. So i'm hoping once I get the injectors replaced it'll be fixed. If not then maybe ported heads are in my future. Definitely looking forward to your update.
Also here's a link to that coolant leak service bulletin the dealer was talking about if you want to read into it more: https://gm.oemdtc.com/9941/ses-lamp-...-chevrolet-gmc |
Funny you mention that TSB. That's exactly the procedure that they took!
Yesterday the service manager called me with an update.
Thankfully nothing was found in the cylinders that were missing yesterday morning. After they checked them out and determined that wasn't the cause they then took to the TSB and found that the injectors were faulty.
It is still waiting at the dealership for its new injectors then hopefully i'll be able to pick the car back up tonight.
I will update this thread when I have more information.