Did the transmission shift before the engine was change, if so was the Bowden cable (throttle valve cable) connected to the linkage, check the cable. Are you sure the transmission has enough fluid, four QTS is not enough. As for the torque converter here is a write up I did on another forum.


The torque converter serves two primary functions. First, it acts as a fluid coupling to smoothly connect engine power through oil to the transmission gear train. Second, it multiplies the torque or twisting effort from the engine when additional performances is desired.

The torque converter consists of three basic elements: the pump (driving member), the turbines (driven or output member), and the stator (reaction member). The converter cover is welded to the pump to seal all three members in oil filled housing. The converter cover is bolted to the engine flex-plate, which is bolted directly to the engine crankshaft. The converter pump is therefore mechanically connected to the engine and turns at engine speed whenever the engine is operating.

When the engine is running and the converter pump is spinning, it acts as a centrifugal pump, picking up oil at its rim between the blades. The shape of the converter pump shells and blades causes this oil to leave the pump spinning in a clockwise direction toward the blades of the turbine. As the oil strikes the turbine blades it imparts a force to the turbine causing it to turn. When the engine is idling and the converter pump is not spinning fast, the force of the oil leaving the pump is not great enough to turn the turbine with any efficiency. This allows the vehicle to stand in gear with the engine idling. As the throttle is opened and the pump speed increases, the force of the oil increases as engine power is more efficiently transmitted to the turbine member and the gear train.

The fluid coupling effect is from the torque converter to the transmission, not from the torque converter to the engine. The engine rotating is the force that puts the transmission fluid into motion (spinning).




Visualize this: if you could slice the torque converter in half, in the car, you will see 2 fans. The transmission side fan is connected to the planetary gears. The engine fan is connected to the engine. The only connection between them is transmission fluid (coupling member). When the transmission fluid is put into motion by the rotation of the engine, it connects both fans, there by transmitting the engine power through the engine fan, to the transmission fluid, to the transmission fan. That’s why you can turn (by hand) the torque converter and turn the engine while not turning the transmission rear wheels. If the engine were running as soon as you step on the gas the transmission would turn. In this form, this torque converter is known as a fluid coupling with no multiplication of torque. For torque multiplication we would need a 3rd member in-between the fans, called a stator.