Why does my 2009 Silverado stay in 4 cylinder Econ when it shouldn't? It doesn't happen all the time. I notice it after I travel 50 miles or more. Most of the time when I shut the motor off for a period of time I can correct the problem. My service garage thinks that I need a transmission control modular and or a solenoid replacement thats located in the transmission. The transmission specialist told me that this is not the problem.

 

need a lot more details to even have an idea, when does it happen? why do you think its when it shouldn't? Any codes or lights/messages? Any other symptoms?

 

I already noted that it usually happens while travling 50 MILES or more. I also noted that I my service garage thinks that I need a TRANSMISSION CONTROL MODULE. The faults that they found are po700 and po742.
I think that I shouldn't because the engine stays in 4 cylinder mode after a stop. This causes the motor to rev as I increase my speed.

 

obviously we had a misunderstanding...maybe someone else will help you

 

Nice try Cleveland - always nice to get shouted at when you try to help someone