mustang engine dying when put into manual first gear

[what9612]

a buddy just installed a used auto transmission in his 96 mustang gt, and it goes just fine in r,n,d but when manually put into 1st the engine dies. any ideas?

 

[dave89iroc]

step 1, what trans?

 

[what9612]

its a 4r70w

 

[what9612]

when he unplugs the torque convertor plug, it can manually shift and stay running. when plugged back in car dies.

 

[fastredgmc]

lock up clutch in the converter is enguaging

 

[what9612]

thats what we were thinking, but what would cause that?

 

[KENNEBELL2.6]

TCC Solenoid? Just a shot in the dark.