So I just had the transmission replaced for a 2001 5.3 Vortec engine . I can run it thru the gears by hand, but if just put into " D " it does not shift thru the gears like it should at acceleration. When put into "D" gear it does not thump ( happily ), giving it gas she starts to move slowly and picks up speed. The tach does not drop when getting up to speed, if I mash the throttle ( example ) @ 50mph in "D" it does not drop into a lower gear, nor does it quickly excelerate.

My thoughts are that I need to take the truck to either a certified transmission guy or Dealership to have it put on the computer.

Thoughts ??

 

Yeah that sounds like a good idea, I will say this it sounds like from what you say about its acceleration that when you put it in drive its trying to start off in the wrong gear like too high of a gear. I've heard of this before that when people put it in drive, the transmission goes into like 3rd gear and try and stay there.

I think the best thing you can do is just bring somewhere to put on the computer.

 

I made an appt. to bring it in to my local Chevy dealership this Friday. I'll update once I get it back.