I've been trying to fix the hesitation in my RX7 ever since I got it a few weeks ago. I first regrounded the pressure sensor, then regrounded the ECU, then added more grounds to the engine and body, but none of that has worked so far. I even tried disconnectiong the vaccum hose from the pressure sensor and the engine still hesitates. You guys have any suggestions of what it could be, i've run out of ideas.

 

A hesitation isn't the secondaries not firing at all; it's more of a momentary problem with the voltage they see (ie a stumble) at the transition point. Regrounding will sometimes fix it, but as you've seen, sometimes it just refuses to go away.

Test the pressure sensor as per the FSM (available for download in the FAQ), and measure voltage at the injectors with a multimeter. With the key in the 'ON' position, you should see 12V at each.