I have a 2012 Avalanche that the dealer just did the plugs and wires on as well as a fuel system cleaning. It is now running more rough compared to before. Even more so when cold and gets a little better when warmed up, but still more shake compared to previously being serviced. No codes are showing as i took it back and they did not see any issues. I drove it a few weeks and took it back again as it is quite a bit different in the smoothness. Any thoughts on what would cause it and not show up on codes or their computers? They have it again now and i am going to go and drive it with them to better explain.
You must be logged in to reply to this topic.