air fuel ratio meter - any1 know about the o2 and airflow sensors

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bigm - 28 Aug 2004 05:01 GMT

I have a 95 maxima (australia) has been a fantastic car, no problems at
all. However I want to install a air/fuel meter. I need to tap into the
oxygen sensor and air flow sensor. I think I have found the o2 sensor
wires at the front of engine (this is where there wires comming from the
sensor plug into the ECU loom?) There is a plug comming from the sensor
which has three wires, one white and two black - which plugs into the
wiring loom which is a red, blue and yellow (the white wire connecting to
the yellow) As far as I understand, one of those wires is the singal wire
- changing between 0.1 and 0.9 volts, depending on the air/fuel ratio. Is
this right ? The other two wires im guessing would be power to heat the
sensor. Does any1 know which wire is the one sending the singal to the ECU
and if it is indeed a singnal of 0.1 to 0.9 volts? Same problem with air
flow meter... is it a vane type in the maxima? and which wire is the
signal wire. Again there are three wires, red black and white. Im
guessing the white one is the singal wire - but does it communicate with
the ECU with a singal of 1-5 volts. With higher voltages with higher
engine loads. I have read that most cars with use this or use a freuency
output. Does anyone know which wire and how it communicates with the ECU ?
Failing this does anyone know where i can score this information - more
detial on the input sensors of the car? Cheers

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Steve T - 28 Aug 2004 08:26 GMT

> I have a 95 maxima (australia) has been a fantastic car, no problems at
> all. However I want to install a air/fuel meter. I need to tap into the
> oxygen sensor and air flow sensor.

All you have to tap into is the O2 sensor wire -not- the AF meter. It's a
simple one wire hook up, plus power and ground.

> There is a plug comming from the sensor
> which has three wires, one white and two black

You hook into the white wire, the other are for the heater.

> - which plugs into the
> wiring loom which is a red, blue and yellow (the white wire connecting to
> the yellow) As far as I understand, one of those wires is the singal wire
> - changing between 0.1 and 0.9 volts, depending on the air/fuel ratio. Is
> this right ?

Yep. In reality it depends on the car where it spends most of it's time. I
use these on old Zcars and I read the .5V to .85V range to tune them. Also
they aren't very accurate in the rich zone, people use the wide band
sensors for that but they cost $$$$$$

> The other two wires im guessing would be power to heat the
> sensor.

Correct.

> Does any1 know which wire is the one sending the singal to the ECU
> and if it is indeed a singnal of 0.1 to 0.9 volts?

It's the white wire and that is the signal it sends.

> Same problem with air
> flow meter... is it a vane type in the maxima? and which wire is the
> signal wire.

You won't hook anything up to it.

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Steve

http://www.atlantaracing.com

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bigm - 30 Aug 2004 04:57 GMT

Thanks heaps for your help - im now building the meter... now i know how to
hook up the o2 sensor - however I have now discovered that the two - one
for each cylinder bank im guessing - which is abit annoying in a way but
your right - they arnt to accurate anyway - im more just installing it so
i know what the engine is up to rather then using it for tuning or
anything. However with this meter - it does seem to require to be hooked
up to the AF sensor - so the question still remains - is it a vane type?
which wire communicates with the ECU? and how - is it though volts from
about 1-5 or does it use a frequency output? I brought the kit from an
electronic store if u want to have a look - here is the link

http://www1.jaycar.com.au/productView.asp?ID=KC5374&CATID=25&keywords=&SPECIAL=&
form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCA
TID=347

is a good place to look at two from little gadgets from ur car

here is another link with some more info on the meter and others

http://www.siliconchip.com.au/cms/A_101150/article.html

If anyone know the info about the Air Flow meter - would be greatly
appreciated

Cheers

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bigm - 30 Aug 2004 05:03 GMT

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Steve T - 30 Aug 2004 06:55 GMT

> Thanks heaps for your help - im now building the meter... now i know how
> to hook up the o2 sensor - however I have now discovered that the two -
[quoted text clipped - 5 lines]
> which wire communicates with the ECU? and how - is it though volts from
> about 1-5 or does it use a frequency output?

It doesn't hook up to the AFM/MAS, I promise you are mistaken on that. At
least I've never seen one that does. Are you sure that extra wire conection
isn't just for the dash light dimmer feature? I can't imagine why it would
want a signal from the AFM and wouldn't use one that did. The site you sent
me to says "While such a design - which works from the car's standard
oxygen sensor -" and says nothing about the AFM/MAS.

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Steve

http://www.atlantaracing.com

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bigm - 31 Aug 2004 04:11 GMT

fair enough - I wish I could send u the instructions becuase it does say it
needs the air sensor - but u very well could be right, u seem to know wot
ur talking about more then me - I will just hook it up without that input
and see how it goes - if it doesnt work - I'll cross that bridge when I
get there

Thanks Heaps for taking the time to help me - greatly appreciated.

Cheers

Mikey

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bigm - 31 Aug 2004 04:14 GMT

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Steve T - 31 Aug 2004 05:12 GMT

> fair enough - I wish I could send u the instructions becuase it does say
> it needs the air sensor

Then I'd return it. None of the others do and IMHO hooking into that signal
is asking for problems. I can't fathom why it would need a signal from the
AFM. BTW there are dozens of free schematics on the web to build these
yourself.

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Steve

http://www.atlantaracing.com

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