The theory is that delaying the 2-3 shift when the engine is cold will cause the engine to warm up and go into closed loop operating mode faster. Closed loop operation begins at a coolant temperature of 60C as long as the ECU receives a valid signal from the O2 sensor.

In the EPA emission certification test that lasts about 45 minutes (including about ten minutes shut down for a hot soak) about 80 percent of total emission occur in the first couple of minutes of operation before the the system goes into closed loop mode.

The strategy of delaying the 2-3 shift to warm up the engine faster is probably effective, but very annoying.

Duke