I've been going through and taking care of my grounds - when I got stuck on the boost sensor ground. I have an 87 TII and the harness has five wires and four plugs. I'm assuming that double wired plug is the ground (it's hard to measure it's voltage because it's become a really bad ground lately) and every search came up with people saying "and I think I'll ground the other wire tomorrow!!!!!!" So I only need to ground the one or should I ground them both? I read the FAQ and searched, but this isn't clear to me. Thanks.

 

did you check out the thread in the archives about grounding? what color are the wires you think are the grounds

 

Ok - so I checked it out and I got one brown with red - a pair of brown with white going into the same terminal - a pair of black with brown looking spots - and a single thicker guage black with white all by itself. Any clue as to which one is the ground? I'm thinking the pair of black/browns, but is there any danger with grounding just one or doing both?

 

Teh answer is hee-ah!

https://www.rx7club.com/showthread.p...threadid=34026

 

still doesn't cover whether the 2 brown wires with black marks on them are the ground(s) or not..

 

Yeah - after a bit of testing a putting in a call to a guy that's won this Mazda mechanics thing turned out that the black with brown spots was apparently used in early RX-7's and that I might as well ground them both while I'm doing it.

 

The brown/red is the output from the sensor to the ECU. The Black/white is 12volts input, the brown/white is the reference voltage(ground that and your car will NEEVER EVER start again), and Brown/black is the ground. Since you have two, I suggest the factory service bulletin has been worked already on your car.

 

for an early model of 86 ? seems weird.
but i did notice when i ran a ground from the boost sensor ground wires to the chassis, and also following the thread in the archives of grounding out the ECU.. my car didn't like it much, and now its barely running,.. even after i took off those extra grounds i made..
so i'm thinking i damaged something, but can't figure out what? any ideas?