What’s up guys,
Having a random cold start rough idle issue with my ‘16 suburban with the ecotec 5.3. This happens completely randomly, typically when colder temperatures outside but not always. MIL will be triggered but will go away after some driving. Some instances it flashes and then will go off. Sometimes when the light is triggered the ABS and stabilitrack light will be on and the transmission will roughly upshift and downshift. The indicator light will go away and typically the shifting will be fixed by shutting the vehicle off for a period of time and then re-starting everything will be back to normal.
From what hat I have gathered U0401 means that the transmission control is not getting good signal during these times.
In regards to the engine, I have between 5-20 misfires counts on all cylinders except #7 which has 80 and #8 which has over 6,000.
Obviously there is a problem with #8, being a non AFM cylinder and being of random occurrence I’m thinking injector or coil pack. Any thoughts?