2000 Tahoe

[Ncobalt]

2000 Tahoe with a 5.3, 4l60e. I bought a Tahoe with a bad rear differential, swapped it out. Both driveshafts disconnected. My question is, when I put into Drive, the transmission takes off on its own. Like someone is press the gas pedal. The speedometer jumps to 50mph then idles down to 20mph?. I am leaning towards a bad torque converter. I never seen this problem before. I need help if anyone heard of something like this

[richard wysong]

Up on stands /lift or on the ground driving?

[asilverblazer]

12 hours ago, Ncobalt said:

Both driveshafts disconnected. My question is, when I put into Drive, the transmission takes off on its own. Like someone is press the gas pedal. The speedometer jumps to 50mph then idles down to 20mph.

Sounds normal to me with no load on the engine or transmission. 

[CamGTP]

Agreed, completely normal if no driveshaft or anything is in the transmission. Nothing is stopping the transmission from turning, so it's just going to start going.