I have a 87 turbo 2 and i have the 3800 rpm stumble i found a old service
news about is and it tells me to run a ground from the boost sensor but i cant
fiqure out which wire of the 4 is the ground please anyone know i would love the help im a noob with rx7's

thanks!

 

Black/White is battery voltage w/key to on. Brown/Red would be close to 2.5 volts w/key to on. Brown/White should have 5 volts w/key to on. The fourth wire is the ground.

 

http://www.aaroncake.net/rx-7/grounding.htm

from this article all the way at the bottom it is the brown/black wire

 

thanks!!! this helped alot!!