Got it. I shal do that now.
Thnx man

 

It is generally bad practice to use a ground both as a low current reference for sensors and as a high current sink for solenoids (fuel injectors). I doubt Mazda did that. However that ground is also used to jumper the fuel pump relay so maybe I am wrong.

Ground #24 is labeled as "emissions ground" in the manual and is most likely used as the ground reference for all the 5 volt sensors used by the CPU (temperature, air flow, throttle position, etc). The oxygen sensor is not a 5 volt sensor but it is a low voltage source that needs the same sensitivity.

The power for the fuel injectors flows from the battery through the resistors then the injectors and finally the ECU switches the ground signal to turn on and off the injectors. There should be a high current ground for the ECU but I haven't found it in the manual.

After you remove the upper intake manifold, you can see ground #24 like in the attachment.

ed

 

The gnds on the top of the rotor housing are the gnds for the ECU.

The gnds for the sensors (afm, tps, boost sensor etc) are all tied together inside the EM harness and terminate at pin 2I on a series four ECU and I can only assume they eventually gnd out thru the gnd wires that tie into the gnds that go to the top of the rotor housing i.e. gnd 24. There are no other gnds for the ECU other than the ones that end up at gnd pt 24. Even the shield of the 02 sensor ties into the gnd pt 24.

I have seen where if you took a meter and put it on ohms, one end on the base of the 02 sensor and the other on say the intake manifold of the engine, the reading would be in the k ohms (why? got me. Exaust gaset material I suppose). That's on a turbo engine I did that.

So what I suggest is to make sure your exaust pipe has a seperate gnd to the chassis. The exaust originally came with a seperate gnd near the mufflers. You've got to have the 02 gnd tied to the engine/ECU in some manner.

 

Odd I unplugd the Boost Sensor and it affect'd nothing.
Is that Normal?

 

SOMTHING ODD HAPPEND!
I ummm... leand my Motor up from the trans..... and the thing Sigled out at one Light and workd Perfectly... till i let it back down..... How odd is that?

 

Yes, it doesn't do a lot in a NA car. You need it but it doesn't do a lot.

 

English?

 

Lmao sorry... i was all over the place.
I had a jack on the back end of the Trans.
I jacked it up till the Shifter base touched the hole.
Outta nowhere the A/f Singled Out and the car Ran Perfect. till i put it down

 

It certainly points to a bad ground between the engine block and the body.

 

I think I posted this: ***So what I suggest is to make sure your exaust pipe has a seperate gnd to the chassis. The exaust originally came with a seperate gnd near the mufflers. You've got to have the 02 gnd tied to the engine/ECU in some manner.*******

The IDEA is that the 02 low band sensor gets it's ground from the exaust pipe. IF the exaust pipe is not making a goode enough connection to the exaust manufold and from there to the engine *block*, your going to get *funny* readings from the low band sensor.

The RX came from the factory with the exaust having a gnd cable. Yours is probably gone.

A simple fix is to make a gnd wire to fit where the 02 screws into the exaust or make a clamp with a gnd wire where the clamp/wire clamp on the metal body of the 02 sensor. The other end to the *block*. Done

 

MAZDA FD Ground Kit
After Getting ****'d Off i was not able to find the Gnd Problem.
So i bought one of these From the Link Above......
Im not sure where the Bad link was. But EVERYTHING that was screwing up. Bad idle Bad A/F reading Slight head light dimming Pick up and Over all Power(including HP) Came Back to a perfect running State.
It is by Use of this That i recomend it to anyone with a Gnd Problem. Check it out for yourself.

(And let me know what you think of it)

 

Down this road lies death!

 

death you say? DEATH!? ummm
i forgot where i was going with that