I'm getting a voltage drop at the data port of 12-11 volts. Off the alternator I'm getting 14. The drop in voltage is making the car back fire sometimes. Anyone have an idea?

 

Ohh check the voltage supply at the PCM.... I use a piercing probe to tap into the wires and a Digital Multi Meter to acurately get readings down to .000 decimals.

Two things.. Bad conection or Bad voltage regulator at the PCM.

You can trace a bad conection... I have now Idea how to trace a bad voltage regulator at the PCM... or even if it has one.

Marvin