anyone know which wire coming out off the ECU is the air,fuel wire???

thanks

 

That seems a simplification of something more complex.

There is a wire that relays the MAF (Mass Air Flow) signal to the PCM. Is that what you mean?

There are wires from the PCM to control the "Fuel" delivery of the injectors.

There is/are wires to the PCM that relay O2 readings, used to measure what the Air/Fuel ratio is.

Have a look in the tech garage. MazdaManic has a comprehensive thread there about installing a "generic" piggy back unit. The thread includes wiring diagram pictures annotated with what wire to splice for some of the various inputs.

Cheers,
Hymee.

 

hi there Hymee, thanks for your time.
I needed the a/f wire for installing a APEXI NA/TURBO timer (out off my last car) in which it has a a/f display with it.
keep up the good work, we need more guys like u.
thanks again.

 

Does the air fuel display require a wideband (current) or narrow band (voltage) type of input?

 

I think it needs a 1volt input, and when the RPM go up the voltage gose down. that is the wire I need.
cos thats how I found the wire with my last car, so therefore is that a narrow band type, and do u know which one it is?
thanks for your time again.
thanks........

 

Now are you talking about an Air/Fuel ratio (lambda) gauge, or an RPM gauge?

Without trying to sound rude, I would think twice about what you are doing - it doesn't sound like you know exactly what you are doing. But it is your car, so why should I say anything to stop you from doing anything to it (good or bad). The warranty boys wouldn't be too impressed if they see wires spliced into.

Comments from others please!

Cheers,
Hymee.

 

As we've read elsewhere, splicing into the ECU loom is not for the faint-hearted. It is not something I would attempt without some proven expertise around. Somewhere I recall there was a thread with the wiring diagram but I can't find it. Or was I imagining it?

 

its a APEXI turbo timer with a/f ratio and O2 read outs, all in one,
( the little silver one )
do u guys know which one /i am talking about,???????

 

I have done all my diagnostic logging via ODBII, not "the loom".

Have a look in the tech garage for MazdaManiac's thread on the install of the EManage controller. He put up wiring diagrams and highlighted certain wires.

BTW - AFR's and O2 are really measurements of the same thing. Do you want wideband O2 or narrow band?

Sorry - I don't have a turbo timer. I have only ever owned NA cars. I believe the only substitute for cubic inches is cubic feet Hehehe.

I reckon if I pressurised the intake of the RX-8, I'd do it with a positive displacement blower. Just thinking out loud! Others would be laughing out load!

Cheers,
Hymee.

 

I bet your turbo timer is only suited to a narrow range O2 sensor. Call the manufacturer and find out.

The RX-8 has a wide range sensor, otherwise called a pump-cell sensor. It has a chamber connected to the exhaust which the pump cell constantly tries to maintain at stoichiometric a/f (14.7:1). It does this by sucking in additional O2 from the exhaust when the mixture in the pump cell is rich, and pumping out O2 when the mixture is lean (to richen it up).

The pump cell is supplied a constant 5 volts (roughly) from the PCM, and its performance is measured by current draw, pumping and sucking (sounds like a B-grade movie) = positive and negative current draw.

What this all boils down to is the fact that the PCM on the RX-8 detects current draw changes from the front O2 sensor, not the voltage - like in a narrow range. I am betting your turbo timer is looking for voltage, not current.

Oh, if you splice into the O2 sensor wire on an RX-8 then whatever you splice in will probably draw current, which will probably make your MIL illuminate.

Do you still want to go cutting wires on your $30,000 car?

 

x 2 = $60,000 car

 

no already given up on the a/f fuel wire, but got the timer working fine....

 

^ gee, now I know why nobody installs AFR gauges in this car

I was searching for a thread that pointed where I could tap in a multimeter to find my Air/Fuel ratio at certain rpms at certain gears.

I wanted to go for an AFR gauge, but decided that a voltmeter or any other means of measurement would be sufficient (if not better).

I wish my CZ unit was here so I could view the logs in my laptop. Damn CZ production backlogs

 

check out www.auterra.com

 

Thanks timbo, but I've ordered Canscan from Harrison. I figure, one tool that gives me AFR readings and more for $140 is quite a bargain!

 

I've also logged AFR and just about everything else with the CAN tool I am developing.

Cheers,
Hymee.

 

so is the standard opinion that you cannot connect an air/fuel gauge to the 8s o2 sensor? I have the inexpensive Megan Racing one just to monitor things before I get the turbo? is it hopeless?

chris

 

I'd suggest you check out Hymee's sCANalyser, in the sig to his post driectly above yours

 

Thanks Timbo.

zz8,

Your RX-8 already has a Wideband 02 sensor. You just need to plug the correct device into the vehicle to read it. One such device is the sCANalyser

Cheers,
Hymee.

 

so does anyone have any helpful hints on connecting the apexi turbo timer to the 8 or any turbo timer for that matter, I have the pen sized turbo timer and want to get it connect so i don''t coke my new turbo

I could not make heads or tails of the shop manual, kinda lost there.