No engine vacuum to a vacuum modulated transmission would result in:

In a vacuum modulated transmission, engine vacuum plays a crucial role in controlling transmission fluid pressure and shift points. When the engine is operating normally, the vacuum modulator utilizes engine vacuum to adjust the hydraulic pressure within the transmission. This adjustment ensures that the transmission shifts smoothly and at the appropriate RPM based on engine load.

When there is no engine vacuum available to the vacuum modulator, the transmission does not receive the necessary signals to lower the hydraulic pressure. As a result, the transmission experiences higher than normal fluid pressures. This can potentially lead to harsh or delayed shifts, as the system is not able to modulate the pressure down to achieve the intended soft shift characteristics.

This understanding highlights why high transmission pressures occur in the absence of engine vacuum, directly impacting the performance of the vehicle's transmission system. The correct answer reflects this important relationship between engine vacuum and transmission behavior.