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#1 2008-06-18 00:18:40

Richardito
Member
From: Houston, TX
Registered: 2005-08-06
User Number: 661
Posts: 43

Correct wire to tap for Air/Fuel gauge install

I've been preparing to install my center pod with three gauges: voltage, boost and air/fuel ratio.  I've been reading in other sites and googling trying to get a definite answer to my question.  Has anybody done this on their 9-2x?  From the paperwork that I'm looking at ('05 WRX) it seems that I need to tap the AF gauge in connector B84, the front oxygen sensor signal (+).  Can anybody confirm this?  Thanks.

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#2 2008-06-18 04:05:18

keaniegenie
92x fanatic
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From: Seattle
Registered: 2006-01-21
User Number: 979
Posts: 795

Re: Correct wire to tap for Air/Fuel gauge install

Do you have to use it?  Air/fuel is only useful when connected to a wideband 02 sensor.


Element 92X

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#3 2008-06-18 09:38:44

rod442
Member
From: Ann Arbor, MI
Registered: 2005-05-13
User Number: 36
Posts: 554

Re: Correct wire to tap for Air/Fuel gauge install

yup, those air fuel gauge's are just a light show.


12 ZX-14R   XCLR8
05 9-2x       SAABARU
00 Formula  INCONTT
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#4 2008-06-18 11:17:06

D-NaSty313
Nothing but PZEV
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From: Rochester, NY/Flint/Detroit
Registered: 2007-06-16
User Number: 2109
Posts: 689

Re: Correct wire to tap for Air/Fuel gauge install

They can tell you if your running lean or rich, but dont give you the actual number


Cobb || APS || Innovate || Ixiz || QTP || AutoMeter || GMS || Tactrix || DBA || STi || Goodridge || CSS || NGK || GReddy
*********OpenSource Tuner*********

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#5 2008-06-18 11:39:59

rod442
Member
From: Ann Arbor, MI
Registered: 2005-05-13
User Number: 36
Posts: 554

Re: Correct wire to tap for Air/Fuel gauge install

If all you want to know is whether or not the sensor is working, then great.  lol.

how much +- stoich can they read?

LED Chart
Lean Range Four red LED’s (.050 to .249V)
Stoichiometric Range Ten yellow LED’s (.250 to .749V)
Rich Range Six green LED’s (.750 to 1.000V)

which, based on autometer's chart doesn't tell you much.

http://www.autometer.com/productPDF/0837L.pdf


12 ZX-14R   XCLR8
05 9-2x       SAABARU
00 Formula  INCONTT
88 Mustang  5LTR LX

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#6 2008-06-18 12:22:38

saab-on-the-cobb
A guy from Nantucket
From: The Beach, NC
Registered: 2006-05-18
User Number: 1135
Posts: 822

Re: Correct wire to tap for Air/Fuel gauge install

You need to install a sensor in your down pipe. The stock signal is worthless.

If you are not using a wideband, you don't need an AF gauge.

The reading from the stock sensor is not at all worth the hassle of the install. Get a real sensor.

sotc


Voted most likely to disagree.

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#7 2008-06-18 13:33:40

SaabRX
2016 BCS FOZ XT
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From: Albany N.Y.
Registered: 2005-07-11
User Number: 502
Posts: 6547

Re: Correct wire to tap for Air/Fuel gauge install

What does a Wideband 02 do? what's it for and why you use it ?

Thanks


2002 WRB Bugeye  5MT Turbo
2005 Black Saabaru 5MT Turbo NEVER SHOULD OF SOLD IT! If I only knew ...
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#8 2008-06-18 18:08:07

D-NaSty313
Nothing but PZEV
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From: Rochester, NY/Flint/Detroit
Registered: 2007-06-16
User Number: 2109
Posts: 689

Re: Correct wire to tap for Air/Fuel gauge install

SaabRX wrote:

What does a Wideband 02 do? what's it for and why you use it ?

Thanks

Its for tuning, it is a oxygen sensor that can read a bunch of different things include actual air fuel ratio.


Cobb || APS || Innovate || Ixiz || QTP || AutoMeter || GMS || Tactrix || DBA || STi || Goodridge || CSS || NGK || GReddy
*********OpenSource Tuner*********

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#9 2008-06-18 18:18:06

keaniegenie
92x fanatic
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From: Seattle
Registered: 2006-01-21
User Number: 979
Posts: 795

Re: Correct wire to tap for Air/Fuel gauge install

SaabRX wrote:

What does a Wideband 02 do? what's it for and why you use it ?

Thanks

It's an air/fuel gauge


Element 92X

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#10 2008-06-18 22:59:54

Rodman
Member
From: Long Island
Registered: 2006-03-01
User Number: 1046
Posts: 2527

Re: Correct wire to tap for Air/Fuel gauge install

As in air fuel mixture, too fat or too lean no good.


2005 satin gray metalic aero, sold. 06 wrx, adios!
2005 black aero, rescue project, jdm STi ver 7 drivetrain.
2005 desert silver aero, work horse JDM EJ205 AVCS
2002 bugeye, sedan :-( new project

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#11 2008-06-19 13:08:37

evengrift
ROLLER BEARING
From: Masshole
Registered: 2007-12-19
User Number: 2450
Posts: 512

Re: Correct wire to tap for Air/Fuel gauge install

A narrowband is nearly, but not completely worthless, if it goes lean at WOT that is a big problem and things are going to go boom soon. I have a narrowband installed specifically for this reason.

Widebands are obviously ideal, but are they worth the trouble?  Tuners will (and should) use their own, not what you have installed. And Wideband sensors have a much shorter life expectancy..

Installing a narrowband in our cars is as easy as tapping the rear O2 sensor wire at the ECU, takes all of 5 minutes...
http://www.gotsalt.net/05ImpDOHC_ECM.jpg


'05 Saabaru RIP

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#12 2008-06-20 00:26:15

Richardito
Member
From: Houston, TX
Registered: 2005-08-06
User Number: 661
Posts: 43

Re: Correct wire to tap for Air/Fuel gauge install

evengrift wrote:

A narrowband is nearly, but not completely worthless, if it goes lean at WOT that is a big problem and things are going to go boom soon. I have a narrowband installed specifically for this reason.

Widebands are obviously ideal, but are they worth the trouble?  Tuners will (and should) use their own, not what you have installed. And Wideband sensors have a much shorter life expectancy..

Installing a narrowband in our cars is as easy as tapping the rear O2 sensor wire at the ECU, takes all of 5 minutes...
http://www.gotsalt.net/05ImpDOHC_ECM.jpg

The problem with tapping into that wire is that is the rear oxygen sensor which is useless.  The computer uses the reading from the rear to compare with the front's reading to make sure that your catalytic converter is functioning correctly.  If it isn't then you get the check engine light.  That's why CEL eliminators are adapters that you wire into the rear O2 sensor harness to fool the computer into thinking that you still have a cat.  Which is the terminal for the Front Oxygen Sensor Signal?

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#13 2008-06-20 17:37:32

evengrift
ROLLER BEARING
From: Masshole
Registered: 2007-12-19
User Number: 2450
Posts: 512

Re: Correct wire to tap for Air/Fuel gauge install

Richardito wrote:

The problem with tapping into that wire is that is the rear oxygen sensor which is useless.  The computer uses the reading from the rear to compare with the front's reading to make sure that your catalytic converter is functioning correctly.  If it isn't then you get the check engine light.  That's why CEL eliminators are adapters that you wire into the rear O2 sensor harness to fool the computer into thinking that you still have a cat.  Which is the terminal for the Front Oxygen Sensor Signal?

Wrong, Wrong, and Wrong.

1) The Rear O2 sensor is the only one that will work, front O2 sensors do not operate on 0-1v. It is far from useless, as a point to probe, consider that tuners stick a wideband probe in your tailpipe!

2) CEL Eliminators work a number of ways, the simplest is putting a plug fowler on the FRONT O2 sensor (as in a cat-less dp install), reducing the exhaust exposure and keeping you from getting a CEL, if your Rear O2 reads richer then your front for any period of time, you're going to get a CEL.

3) I'm not telling which is for the front, because of the above. If you don't understand that, you do not need to be hacking on your harness.

Last edited by evengrift (2008-06-20 17:45:02)


'05 Saabaru RIP

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#14 2008-06-20 17:41:22

92XLOVER
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Supporter
From: Andrews AFB, MD
Registered: 2007-02-26
User Number: 1856
Posts: 495

Re: Correct wire to tap for Air/Fuel gauge install

evengrift, for the above though... embeer for you! eh, why not,  embeer embeer


05 9-2X Aero, Loaded, IxizHood

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#15 2008-06-20 18:26:10

Richardito
Member
From: Houston, TX
Registered: 2005-08-06
User Number: 661
Posts: 43

Re: Correct wire to tap for Air/Fuel gauge install

evengrift wrote:

Richardito wrote:

The problem with tapping into that wire is that is the rear oxygen sensor which is useless.  The computer uses the reading from the rear to compare with the front's reading to make sure that your catalytic converter is functioning correctly.  If it isn't then you get the check engine light.  That's why CEL eliminators are adapters that you wire into the rear O2 sensor harness to fool the computer into thinking that you still have a cat.  Which is the terminal for the Front Oxygen Sensor Signal?

Wrong, Wrong, and Wrong.

1) The Rear O2 sensor is the only one that will work, front O2 sensors do not operate on 0-1v. It is far from useless, as a point to probe, consider that tuners stick a wideband probe in your tailpipe!

2) CEL Eliminators work a number of ways, the simplest is putting a plug fowler on the FRONT O2 sensor (as in a cat-less dp install), reducing the exhaust exposure and keeping you from getting a CEL, if your Rear O2 reads richer then your front for any period of time, you're going to get a CEL.

3) I'm not telling which is for the front, because of the above. If you don't understand that, you do not need to be hacking on your harness.

OK, I'm an engineer so I understand that and much more.  banana I do not know your background, so I will explain why cars have an O2 sensor before and after the catalytic converter.  The first O2 sensor checks for the available oxygen after the combustion.  The car computer then decides if the mix needs more or less fuel.  Then the gas goes thru the cat converter.  There the exhaust gases are further oxidized (for example- from CO to CO2).  The second O2 sensor then checks for the available oxygen to verify that the cat converter is doing it's job.  It does this by verifying that the amount of O2 has come down from the first reading (first O2 sensor).  If it hasn't then it will warn the computer that something is wrong (your cat is not working or you do not have one).

I realize that the voltage from the front O2 sensor is beyond the specification and why it can't be used.  That is a bummer.  I'm pretty sure that when I installed an A/F gauge on my turbo Talon I connected it to the front O2 sensor.  But that was a long time ago...  Since I already have the gauge and I need three for my center pod I will hook it up anyways.


P.S. the rear O2 sensor will always read richer (fuel vs. O2) than the front one.  Since there will be less free O2 after the oxidation of the other species and the amount of fuel will be kept constant.  Simple conservation of mass and energy rule.

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#16 2008-06-20 19:22:14

evengrift
ROLLER BEARING
From: Masshole
Registered: 2007-12-19
User Number: 2450
Posts: 512

Re: Correct wire to tap for Air/Fuel gauge install

Richardito wrote:

I realize that the voltage from the front O2 sensor is beyond the specification and why it can't be used.  That is a bummer.  I'm pretty sure that when I installed an A/F gauge on my turbo Talon I connected it to the front O2 sensor.  But that was a long time ago...  Since I already have the gauge and I need three for my center pod I will hook it up anyways.

If you're an EE, actually translating the front sensor output to 0-1v would be OMG easy. But if you understand what's happening, you'll also know there's no value in doing it.

Richardito wrote:

P.S. the rear O2 sensor will always read richer (fuel vs. O2) than the front one.  Since there will be less free O2 after the oxidation of the other species and the amount of fuel will be kept constant.  Simple conservation of mass and energy rule.

This is patently false, as I've actually done this, I had a wideband in my DSM O2 housing, and pulled the signal off the 2 lead O2. One of the main functions of a catalytic converter is actually to burn previously unburned hydrocarbons.  But nevermind that, in our cars (unless modded) the exhaust has already gone through a cat before hitting the first O2 sensor.

At any rate, the effectiveness of catalytic converters being what it is, and the accuracy of narrowband O2 sensors being what they are, the placement of the O2 sensor is almost irrelevant in our cars.


'05 Saabaru RIP

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#17 2008-06-22 02:01:57

Richardito
Member
From: Houston, TX
Registered: 2005-08-06
User Number: 661
Posts: 43

Re: Correct wire to tap for Air/Fuel gauge install

evengrift wrote:

Richardito wrote:

I realize that the voltage from the front O2 sensor is beyond the specification and why it can't be used.  That is a bummer.  I'm pretty sure that when I installed an A/F gauge on my turbo Talon I connected it to the front O2 sensor.  But that was a long time ago...  Since I already have the gauge and I need three for my center pod I will hook it up anyways.

If you're an EE, actually translating the front sensor output to 0-1v would be OMG easy. But if you understand what's happening, you'll also know there's no value in doing it.

Richardito wrote:

P.S. the rear O2 sensor will always read richer (fuel vs. O2) than the front one.  Since there will be less free O2 after the oxidation of the other species and the amount of fuel will be kept constant.  Simple conservation of mass and energy rule.

This is patently false, as I've actually done this, I had a wideband in my DSM O2 housing, and pulled the signal off the 2 lead O2. One of the main functions of a catalytic converter is actually to burn previously unburned hydrocarbons.  But nevermind that, in our cars (unless modded) the exhaust has already gone through a cat before hitting the first O2 sensor.

At any rate, the effectiveness of catalytic converters being what it is, and the accuracy of narrowband O2 sensors being what they are, the placement of the O2 sensor is almost irrelevant in our cars.

I will go ahead and install the A/F gauge on the B135 connector and call it a day.  Using "burn" to describe the function of a cat converter is incorrect since there is no combustion taking place there.  The high surface area and the carefully balance mixture of metals, etc. catalyzes the reduction of species like NOx and the oxidation of species like CO to less harmful ones like CO2 (reduction is the opposite of oxidation).  Like the name states, it is a catalyst so it does not takes part in the actual reaction so it does not need replacement because it is never spent.  The placement of many cats and pre-cats is to increase the efficiency of the reduction/oxidation process in one pass through the exhaust.   



From Wikipedia:


Three-way catalytic converters

A three-way catalytic converter has three simultaneous tasks:

   1. Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2
   2. Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2
   3. Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: 2CxHy + (2x+y/2)O2 → 2xCO2 + yH2O

These three reactions occur most efficiently when the catalytic converter receives exhaust from an engine running slightly above the stoichiometric point. This is between 14.8 and 14.9 parts air to 1 part fuel, by weight, for gasoline (the ratio for LPG, natural gas and ethanol fuels is slightly different, requiring modified fuel system settings when using those fuels). When there is more oxygen than required, then the system is said to be running lean, and the system is in oxidizing condition. In that case, the converter's two oxidizing reactions (oxidation of CO and hydrocarbons) are favoured, at the expense of the reducing reaction. When there is excessive fuel, then the engine is running rich. The reduction of NOx is favoured, at the expense of CO and HC oxidation. If an engine could be operated with infinitesimally small oscillations about the stoichiometric point for the fuel used, it is theoretically possible to reach 100% conversion efficiencies.

Since 1981, three-way catalytic converters have been at the heart of vehicle emission control systems in North American roadgoing vehicles, and have been used on "large spark ignition" (LSI) engines since 2001 in California, and from 2004 in the other 49 states.[citation needed] LSI engines are used in forklifts, aerial boom lifts, ice resurfacing machines and construction equipment. The converters used in those types of machines are three-way types, and are designed to reduce combined NOx+HC emissions from 12 gram/BHP-hour to 3 gram/BHP-hour or less, as mandated by the United States Environmental Protection Agency's (EPA) 2004 regulations.[citation needed] A further drop to 2 gram/BHP-hour of NOx+HC emissions is mandated in 2007[citation needed] (note: NOx is the industry standard short form for nitric oxide (NO) and nitrogen dioxide (NO2) both of which are smog precursors. HC is the industry short form for hydrocarbons). The EPA intends to introduce emissions rules for stationary spark ignition engines, to take effect in January 2008.[1]

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#18 2008-06-22 10:56:01

evengrift
ROLLER BEARING
From: Masshole
Registered: 2007-12-19
User Number: 2450
Posts: 512

Re: Correct wire to tap for Air/Fuel gauge install

arrow-up I obviously didn't mean burn in a literal sense. Anyone who understands the definition of "catalyzer" be it in this scenario or other should get that.

Although combustion has taken place in catalytic converters when cars run excessively rich for a long time..  This usually kills the catalytic converter. (and sometimes starts under-car fires)

Posting remedial and mundane articles from wikipedia will hardly garner you any favor. Consider I was trying to help you with something you didn't understand or have knowledge about.

No good deed goes unpunished..


'05 Saabaru RIP

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#19 2008-06-23 09:27:27

Richardito
Member
From: Houston, TX
Registered: 2005-08-06
User Number: 661
Posts: 43

Re: Correct wire to tap for Air/Fuel gauge install

evengrift wrote:

arrow-up I obviously didn't mean burn in a literal sense. Anyone who understands the definition of "catalyzer" be it in this scenario or other should get that.

Although combustion has taken place in catalytic converters when cars run excessively rich for a long time..  This usually kills the catalytic converter. (and sometimes starts under-car fires)

Posting remedial and mundane articles from wikipedia will hardly garner you any favor. Consider I was trying to help you with something you didn't understand or have knowledge about.

No good deed goes unpunished..

Well, I like things clear and without any discrepancy (I guess I'm a good engineer).  I do not like to confuse others that might read this thread. Wikipedia was the first place I found the info and after skimming through it looked legit and compact.  Your criticism is not welcomed or needed.  I am not looking for any favors from anyone and excuse me but I understand what I'm talking about.  Did you forgot that I am an Engineer?  I just wanted to have an intelligent conversation about my question.  I had already taken a look at the wiring chart but I wanted to make sure before I started the install.  I guess as you get older you get more cautious.

    I remember than when I got my '95 5.0 Mustang GT I used to visit the Saleem forums daily to learn about the car.  There were a lot of knowledgeable folks that posted responses with no attitudes and without talking down to anyone.  I also had a 300ZX while in college and I had already learned a lot by doing all of the maintenance myself including changing the timing belt and the water pump after a botched engine re-build by a so-called mechanic.  I eventually was able to put the car back in 100% working condition by myself.  For some reason now a days you get either a bit or a lot of attitude, regardless which forum you post in.  I guess that says a lot about our current state of mind and of our "pack" mentality.

    Thanks for everyone's help, I really appreciate everyone's time and effort in responding and helping me with this.  I'll install my gauges in a couple of weeks and will be very happy.  I am waiting for the warranty to expire before going to Stage 2 and about six months later I will upgrade the turbo.  Probably will use a VF34 turbo in my case since I have an automatic transmission.  After I do this I will surely post kind of an install guide to help everyone out there that wants to do something similar.  Thanks again.

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#20 2008-06-23 09:31:42

Chad W
Supporter
Supporter
Registered: 2005-05-27
User Number: 104
Posts: 3349

Re: Correct wire to tap for Air/Fuel gauge install

NEEERRDDDDD FIGGGGGHHHHHTTTTTTT!!!!!!!


2013 DGM OBP  6spd
Enkei | Falken | Azenis | Tsudo | Polk | Pioneer

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#21 2008-06-23 09:51:36

evengrift
ROLLER BEARING
From: Masshole
Registered: 2007-12-19
User Number: 2450
Posts: 512

Re: Correct wire to tap for Air/Fuel gauge install

Richardito wrote:

Well, I like things clear and without any discrepancy (I guess I'm a good engineer).  I do not like to confuse others that might read this thread. Wikipedia was the first place I found the info and after skimming through it looked legit and compact.  Your criticism is not welcomed or needed.  I am not looking for any favors from anyone and excuse me but I understand what I'm talking about.  Did you forgot that I am an Engineer?  I just wanted to have an intelligent conversation about my question.  I had already taken a look at the wiring chart but I wanted to make sure before I started the install.  I guess as you get older you get more cautious.

    I remember than when I got my '95 5.0 Mustang GT I used to visit the Saleem forums daily to learn about the car.  There were a lot of knowledgeable folks that posted responses with no attitudes and without talking down to anyone.  I also had a 300ZX while in college and I had already learned a lot by doing all of the maintenance myself including changing the timing belt and the water pump after a botched engine re-build by a so-called mechanic.  I eventually was able to put the car back in 100% working condition by myself.  For some reason now a days you get either a bit or a lot of attitude, regardless which forum you post in.  I guess that says a lot about our current state of mind and of our "pack" mentality.

    Thanks for everyone's help, I really appreciate everyone's time and effort in responding and helping me with this.  I'll install my gauges in a couple of weeks and will be very happy.  I am waiting for the warranty to expire before going to Stage 2 and about six months later I will upgrade the turbo.  Probably will use a VF34 turbo in my case since I have an automatic transmission.  After I do this I will surely post kind of an install guide to help everyone out there that wants to do something similar.  Thanks again.

You're an engineer and infallible, got it. http://www.cnn.com/TECH/space/9909/30/mars.metric/

You wanted to have an intelligent conversation?  But you responded with acerbic and false claims about the information I provided, not questions. You want a no-attitude response?  Skip the attitude in your posts.

Who is the "everyone" in the "everyone's" help?  Everyone but me?  The person who actually did help you?

You're the expert, you know everything, no one here could possibly know something you don't, funny then how this got started with you asking which wire to tap for a simple narrowband a/f gauge install..

Oh and by the way, you go and write an install guide for your turbo, there are only a few hundred out there, and there's nothing special about a VF-34 install..  You can teach us all what we already know..  And, my god son some of us are oh so much further down the development path you're embarking on..

Last edited by evengrift (2008-06-23 09:54:32)


'05 Saabaru RIP

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#22 2008-08-09 02:21:32

Richardito
Member
From: Houston, TX
Registered: 2005-08-06
User Number: 661
Posts: 43

Re: Correct wire to tap for Air/Fuel gauge install

lol  lol  Some people are so touchy...  I just stumbled into this thread since June and it is very funny re-reading parts of it.   driving 

I should use that in my sig:  "The Infallible Engineer".   lol  lol

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#23 2019-12-11 20:19:32

ayumuyume
Member
Registered: 2019-11-05
User Number: 46677
Posts: 7

Re: Correct wire to tap for Air/Fuel gauge install

bump from the dead.
So if I happen to have a narrowband from a previous car I can use that in the dash, but will still need a separate wideband setup to stick in the tailpipe when I start tuning?

What's best for tuning with an openport?

Last edited by ayumuyume (2019-12-11 20:21:03)

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