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wideband oxygen sensor / afr sensors
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mtthhrs Offline
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Post: #1
wideband oxygen sensor / afr sensors
!!!HELP!!! I have a 2004 nissan titan. I have hooked up an HHO generator. I think I had some initiall mpg gains but they dissapeared. I was wondering if an efie will work and if not what will? I have nissans service manual and it calls the O2 sensors air fuel ratio sensors but the dealership tech said they're wideband oxygen sensors. I also have auterra dyno-scan software for my laptop that I can use. The sensor it's self has 5 wires comming out of it but after the connector it has 6 wire's the nissan tech said the sixth wire is just a shield wire. Also I have no idea which is the signal wire even with the manual. I should be able to include some attachments of my manual later if that would help.

Matt
(This post was last modified: 07-01-2008 05:56 AM by mtthhrs.)
05-27-2008 07:04 PM
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michiba Offline
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Post: #2
RE: wideband oxygen sensor
I have a 2006 Nissan Titan, but I think the sensors are the same. Too many! The two post cat sensors in bank 1 and 2 are the old style O2 sensors (HO2S2) that range between 0 and 1V in a sinusoidal like waveform. I disconnected mine as a test and no DTC codes were thrown. The manual says that “Under normal conditions, the heated oxygen sensor 2 is not used for engine control operation”. The other two sensors in bank 1 and 2 are pre-cat and are more complicated AFR sensors (A/F SENSOR 1) and NOT improved wideband sensors. There seems to be some confusion (maybe it’s me that confused) where wideband is the term given to AFR sensors. AFRs are based on current where wideband are still voltage based but give lower and higher limits to determine the oxygen level in the exhaust stream.

EFIEs won't work on AFRs. Your pre cat sensors are AFR type which is an enhancement of the wide range O2 sensors. I am having the same issue trying to figure out what to do with the newer AFR type sensors that rely on current flow.

The following information has been very helpful for me to understand these sensors.

Good article explaining their operation and actual testing results.
http://www.babcox.com/editorial/us/us10226.htm

An approach recommended is as follows:
http://www.fuelsaver-mpg.com/doc/TuningForMileage.html
Go to the AFR Sensors section about 7/8 down the page. However, I do not think this approach is ideal which I will explain below.

A good article explaining the Toyota sensors:
http://www.autoshop101.com/forms/h37.pdf

Another good link to explain the AFRs is as follows:
http://wbo2.com/lsu/lsuworks.htm

From what I can figure reading the 2006 Titan manual engine control and electronics section, the pinout for the AFR sensor on the Titan is as follows:
Pin 1 - UN1 = 3.1V UN1 Vs sense voltage
Pin 2 - IA1 = 2.3V IA1 current line
Pin 3 - Power
Pin 4 - H1 = Heater Power
Pin 5 - VM1 = 2.6V VM1 low voltage reference
Pin 6 - IP1 = 2.3V IP1 current line

I think you had mentioned in your post that only 5 of the wires were connected. This likely means that one of the 2.3V current sense lines may be the calibration line or Rcal. The sensor is either calibrated in free air, or there is some sort of resistor in the harness and the ECM is performing the calibration. Either way, I would not touch either of the 2.3V lines. The 3.1V (UN1 - pin 1) line is probably the voltage sense line used by the ECM. The 2.6V (VM1 - pin 5) line is the low end reference voltage. Notice that the difference in voltage between Pin 1 and Pin 5 is .5V or about 500mV. I think this is the 450mV reference that the ECM uses to determine if the sensor is lean or rich then adjusts the current +/- accordingly.

Explanation as to why I think the TuningForMileage AFR Sensor recommendation may not be ideal:
“To alter an AFR sensor, cut the blue signal wire and install low value resistors.” Assuming the blue wire is the current sense wire. This may not a good assumption for all AFR sensors since not all have blue wires in the harness including our Titan. If the ECM is using the current flow and amount to determine the mixture, adding a resistance will narrow the range of correction for both lean and rich. So, if using an electrolyzer, you should see leaner values from the AFR. The leaner values will be in the form of a slightly HIGHER voltage (opposite of the WRAF and older O2 sensors) and a current flow in a positive direction when using an amp meter in line with the signal input. Let’s say the current is +5mA. Adding a small resistance on the line may reduce the amperage and thus the amount of fuel the computer will inject. So I think this approach may work. However, it will work in the opposite direction too when current flows in the (-) direction. Meaning, if you begin to run too rich and need to lean, the computer will not lean out as much. Also, without knowing the impedance of the current loop to/from the ECM, choosing an initial resistance value may risk damaging the ECM. I could be wrong though as mpgmike has had more experience in faking out the AFRs.

I think the best approach to defeat the AFR sensor electronically is to use a resistor divider to lower the voltage of pin 1, UNI Vs line. The way I plan on doing it is as follows:
- Get a 1M ohm POT (variable resistor) and configure it to be at its max value of 1M.
- Strip a section on pin 1 wire to connect one side of the POT. Strip the wire after the harness connector (the wire that goes from the harness to the ECM). Don't mess w/ the sensor wiring as it is special for high temp applications. Don't connect the other end of the POT to anything yet and insulate it so that it does not short to something else.
- Start up truck and let idle.
- Measure the voltage on pin 1. According to the manual, it should be around 3.3V.
- Then, connect the other end of the POT to ground. I would start with at least 1M ohms, max value. The larger the resistance, the least likely you are to kill the voltage to 0 if the impedance (resistance) of pin 1 is high.
- Measure the voltage. A small change would indicate a high impedance on pin 1. A drop in voltage close to 1/2 the voltage would mean that the impedance on pin 1 is also high. Now is where the experimentation begins to determine the best voltage offset similar to how Mike advises to setup the EFIE.
- Vary the POT value to determine the best offset voltage. As Mike has advised for the EFIE, I would try a similar offset of -100mV.
- If the voltage drop is high which I would find unlikely, a higher value POT will be needed to make smaller negative offset adjustments

Anyone feel free to correct me if any of the above analysis seems wrong.

To keep out of the electronics, I would say try O2 spacers or spark plug anti-foulers to help fake out the AFRs.

If I can get to the point where I can start seeing some mileage gains being offset by my computer, I will try the method above on the AFRs. I have yet to
see any significant mileage gains using the electrolyzer I made per water4gas and using a ScanguageII for measurements. You had mentioned that you were seeing some mileage gains. How did you figure out that you have gains?

Maybe you or someone can help me figure out if I am generating enough HHO from my electrolyzer.
- Distilled water = 650ml
- Baking soda = 1 teaspoon
- Amperage = 6.8A when feeding into a vacuum line
- I am using the EVAP vacuum line to pull in the HHO
- I displace 500mL in about 6 ½ minutes with gas from the electrolyzer

What is the amount of HHO I need to be producing w/o vacuum? i.e. My measurements of production have been with the electrolyzer bubbler off and filling a bottle with just the HHO gas from the electrolyzer.

I am happy to see another Titan owner trying this out.
Mik

PS. Mike, great forum for all of us to research and learn others experiences. Thanks.
05-29-2008 08:29 PM
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qsiguy Offline
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Post: #3
RE: wideband oxygen sensor
I am also at a loss when it comes to these newer O2 sensors and have not yet had an opportunity to check one out. I do have a few observations on your analysis. The way you are talking about wiring the pot to Pin 1 of your O2 seem incorrect. The way you described it, you will be tapping in to the Pin 1 wire to a pot, center pole I assume? Then one outer pole to ground. If this is how you intend to wire, this is not a resistor/divider circuit. You are just increasing the load on the Pin 1 wire. To wire this using a resistor divider circuit you will need to use all three pot terminals. One outer terminal to ground, the other outer to the voltage source (you'll need to determine for sure if the ~3 volts is coming out of the O2 sensor or coming from the ECU), and the center pot terminal is the voltage out. You will be cutting the wire coming from Pin 1. When the pot is turned all the way one direction you have full voltage/no change, with the pot the other way you have 0 volts output. If I'm understanding you properly on your wiring, you could easily damage either your O2 sensor or the ECU wiring it that way.

O2 spacers don't accomplish what we normally want to do to increase mileage. An O2 spacer will make the sensor see a leaner condition which will cause the ECU to add fuel. This is the opposite of what we want to do. O2 spacers are often used by people who are eliminating the cat on the post cat O2 sensor. They want it to see a leaner condition so the ECU believes the cat is still installed and burning off some fuel.

Sounds like your generator isn't making much HHO. From your numbers you are only making about 77 mL per minute. Most fairly efficient generators I've heard of produce about 500-1000 mL per minute. My first generator would produce just under 500 mL per minute and it wasn't efficient enough to provide me any gains. Of course that output was generated at about 12-15 amps.

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(This post was last modified: 05-30-2008 10:49 AM by qsiguy.)
05-30-2008 10:47 AM
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michiba Offline
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Post: #4
RE: wideband oxygen sensor
qsiguy Wrote:I am also at a loss when it comes to these newer O2 sensors and have not yet had an opportunity to check one out. I do have a few observations on your analysis. The way you are talking about wiring the pot to Pin 1 of your O2 seem incorrect. The way you described it, you will be tapping in to the Pin 1 wire to a pot, center pole I assume? Then one outer pole to ground. If this is how you intend to wire, this is not a resistor/divider circuit. You are just increasing the load on the Pin 1 wire. To wire this using a resistor divider circuit you will need to use all three pot terminals. One outer terminal to ground, the other outer to the voltage source (you'll need to determine for sure if the ~3 volts is coming out of the O2 sensor or coming from the ECU), and the center pot terminal is the voltage out. You will be cutting the wire coming from Pin 1. When the pot is turned all the way one direction you have full voltage/no change, with the pot the other way you have 0 volts output. If I'm understanding you properly on your wiring, you could easily damage either your O2 sensor or the ECU wiring it that way.

O2 spacers don't accomplish what we normally want to do to increase mileage. An O2 spacer will make the sensor see a leaner condition which will cause the ECU to add fuel. This is the opposite of what we want to do. O2 spacers are often used by people who are eliminating the cat on the post cat O2 sensor. They want it to see a leaner condition so the ECU believes the cat is still installed and burning off some fuel.

Sounds like your generator isn't making much HHO. From your numbers you are only making about 77 mL per minute. Most fairly efficient generators I've heard of produce about 500-1000 mL per minute. My first generator would produce just under 500 mL per minute and it wasn't efficient enough to provide me any gains. Of course that output was generated at about 12-15 amps.

Thanks qsiguy. You are right about the POT. I did not explain it correctly. Pin 1 to the 3.1V signal from the sensor, pin 2 to the ECM, and pin 3 to ground. I was assuming that 3.1V was coming from the sensor, but it would be best to make sure as you stated.

The O2 spacer idea was taken from another forum thread:
http://www.fuel-saver.org/showthread.php?tid=220
Maybe I misinterpreted, I think you have more experience here, so I appreciate your feedback.

I am going to have to figure out how to generate more HHO. Having a 5.7L V8, I guess I will need alot more.

mtthhrs, what are using for an HHO generator and how did you measure the gains?

Mik
05-30-2008 04:55 PM
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mtthhrs Offline
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Post: #5
RE: wideband oxygen sensor
[/quote]

Thanks qsiguy. You are right about the POT. I did not explain it correctly. Pin 1 to the 3.1V signal from the sensor, pin 2 to the ECM, and pin 3 to ground. I was assuming that 3.1V was coming from the sensor, but it would be best to make sure as you stated.

The O2 spacer idea was taken from another forum thread:
http://www.fuel-saver.org/showthread.php?tid=220
Maybe I misinterpreted, I think you have more experience here, so I appreciate your feedback.

I am going to have to figure out how to generate more HHO. Having a 5.7L V8, I guess I will need alot more.

mtthhrs, what are using for an HHO generator and how did you measure the gains?

Mik
[/quote]

I'm using 2 water4gas jars hooked up in a series pulling about 6 amps not sure how much hho it makes. I used auterra dyno-scan program for my laptop. It showed I gained about 4 mpg for one evening along a 6 mile route I usually travel. Let's keep each other posted about how our progects going. And thanks both of you for your help.

Matt
05-30-2008 08:44 PM
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michiba Offline
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Post: #6
RE: wideband oxygen sensor

Thanks qsiguy. You are right about the POT. I did not explain it correctly. Pin 1 to the 3.1V signal from the sensor, pin 2 to the ECM, and pin 3 to ground. I was assuming that 3.1V was coming from the sensor, but it would be best to make sure as you stated.

The O2 spacer idea was taken from another forum thread:
http://www.fuel-saver.org/showthread.php?tid=220
Maybe I misinterpreted, I think you have more experience here, so I appreciate your feedback.

I am going to have to figure out how to generate more HHO. Having a 5.7L V8, I guess I will need alot more.

mtthhrs, what are using for an HHO generator and how did you measure the gains?

Mik
[/quote]

I'm using 2 water4gas jars hooked up in a series pulling about 6 amps not sure how much hho it makes. I used auterra dyno-scan program for my laptop. It showed I gained about 4 mpg for one evening along a 6 mile route I usually travel. Let's keep each other posted about how our progects going. And thanks both of you for your help.
[/quote]

Are you feeding the HHO of each jar into a PCV or both jars HHO in series to the EVAP vacuum line?
05-31-2008 11:05 AM
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mtthhrs Offline
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Post: #7
RE: wideband oxygen sensor
[/quote]
Are you feeding the HHO of each jar into a PCV or both jars HHO in series to the EVAP vacuum line?
[/quote]

I hooked them up in a series electrically. Then I had to ad about 6 teaspons of baking soda. But it is more efficent. I have dual outputs coming out of the jars one goes to the evap vaccum line the other I tapped into the air intake just before the throttle body. I conected the outputs from the jars with Ts so that I'd just have one line going to the evap and one going to the air intake. But then u should put in some check valves. If you connect both jars with a T and route it to the evap vaccum line that should be fine. If you want to later on you could add dual outputs.

Matt
05-31-2008 01:28 PM
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aespeedy47 Offline
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Post: #8
RE: wideband oxygen sensor
hello guys it looks like i found the right place. i have an 06 armada and im just dying to get a system up and running on my SUV but before i go diving head first into it im doing my research and i too have the manual to my vehicle and saw that instead of o2 sensors i had 5 wire a/f sensors. im electrically and mechanically inclined but im kind of sort of at a standstill with what to do. michiba you said to put that 1Mohm pot in series with the a/f sensors, how has it worked out for you? does anyone else know of any other information out there to trick these 5 wire/wideband a/f sensors with results? lol i bought this vehicle last year so me and my family can go places but now its too expensive for me and my kids to go anywhere now, i need this to work or im up you know what creek without a paddle.
06-06-2008 02:16 PM
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mtthhrs Offline
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Post: #9
RE: wideband oxygen sensor
aespeedy47 Wrote:hello guys it looks like i found the right place. i have an 06 armada and im just dying to get a system up and running on my SUV but before i go diving head first into it im doing my research and i too have the manual to my vehicle and saw that instead of o2 sensors i had 5 wire a/f sensors. im electrically and mechanically inclined but im kind of sort of at a standstill with what to do. michiba you said to put that 1Mohm pot in series with the a/f sensors, how has it worked out for you? does anyone else know of any other information out there to trick these 5 wire/wideband a/f sensors with results? lol i bought this vehicle last year so me and my family can go places but now its too expensive for me and my kids to go anywhere now, i need this to work or im up you know what creek without a paddle.

I emailed george wiseman at eagle research he said they figured out that an efie works for air fuel ratio sensors too. I'm still waiting for the details though on how to connect it. Wouldn't you need to use a lot lower resistance pot for a voltage spliting circuit though.

Matt
06-06-2008 02:47 PM
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qsiguy Offline
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Post: #10
RE: wideband oxygen sensor
My understanding was that the 5 wire wideband sensors could be offset with the EFIE but the 4 wire AFR's could not as they operate on current. I believe it's all just discussion at this point. I have not personally tried one yet nor have I heard from anyone that's actually done it. It is going to take some good research.

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06-06-2008 03:25 PM
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