Hey, my Fc has some problems idling and i have been told it could be related to a ground issue... i have read the write up on rr.. but im confuesed.. my wiring on my fc is all messed up and i dont know even if it has the ground wires.. so i would like to know what custom grounds to run conisstering my fc has no grounds wires.... detaled explaintions would be nice but pictures would soooo awsome

Please help me out


Thanx


Dustin

 

My suggestion to you is that you need to read some wiring diagrams and follow the directions on the write-up. It's pretty cut and dry.

 

The battery has a ground cable.

It runs from the battery to the chassis just below the left strut tower, then it continues to the long bolt on the starter. Those are the two main grounds. Battery to chassis to engine. There are some suppelmental grounds. One is for the ECU internals. That ground is located on top of the rear rotor housing. Its on a ring terminal about 3inches left of BL zero.

There is another ground from near the wiper motor to the engine.

The Lead and Trail coils assy's are gounded thru their attach points. If you put these two coil assy on a piece of wood....the car won't start. The attach bolts for them are more than adequate IF you have a good chassis ground as mentioned in the above writing.

If your obsessed with the grounds on a RX...go to the schematics that are online for a free download. There you will find the locations for ALL the grounds on the car. Each and everyone of them.

 

Here are the grounds on a series four.

 

Biggergrounds

 

Very good, Hailers

Technically the wire between the tranny and the firewall is a bonding strap, it's really not needed if all of the housing-to-housing contact is nice and clean (but whose is, lol?).

Wankel- if yours is an '88, please don't ground that boost sensor as called for in that writeup. It will screw with the ECU's head. From what I can gather, that ground was recommended by Mazda on the very early S4's ('86) because of some production snafu. Also, unless you remove the original grounds, just about any wires you add now will all be considered bonding jumpers, which may or may not help. Attach one ground at a time, and see how the car performs. If she runs like crap after installing one, quickly remove it (it's "fighting" with the OEM ground, for lack of a better technical explanation)...

 

Is that just one big wire? Do I need a special kind of wire? I'm a noob with this but think this might be part of my issue. Is the ground wire a specific color?

 

What are you talking about? The negative battery cable? If so, yes, it's one big wire. At the left strut tower, as it passes by, the insulation is stripped and a metal "standoff" is clamped around the bare wire and bolted to ground. Most of the car's grounds all over the chassis use this point for return to the battery (or power from the battery, depending on which version of electrical flow you subscribe to, lol).

As far as engine performance goes, that rear rotor housing is your most important ground, and by extension, the big neg cable at the starter...

 

wile your down there check the vacuum hoses. try behind that upper manifold. and in front, vac rac rack and on the passenger side of the engine for corroded hoses. thats my 2 cents