My car has an 4l60e trans and I have noticed that when I accelerate, it doesn't downshift to a lower gear and this causes the motor to bog down. I purchased this motor and transmission from someone to place in my car so I don't know much about its history. Any thoughts on what I can do to fix this problem?

 

Are you running and Computer tuner of any sort?

 

No it is a stock engine and the tranny has a shift kit. From a stop it will shift through the gears with no problem .