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1.5v Upstream Sensor in Nissan Frontier
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Mik3h Offline
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Post: #1
1.5v Upstream Sensor in Nissan Frontier
Haven't seen anything on this, so here's something new?
Trying to install a Dual EFIE from GreenTech and I'd hate to cut the wrong wires!
I have a 4L 2007 Frontier and I'm having challenges with the shop manual (online from AutoZone-THANKS!).

It states the upstream sensors (before the first '3-way catalyst') (2ea) are Air/Fuel Ratio sensors and show 6 wires for this device, expecting 3.1v, 2.6v, 2.3v, and 2.3v on 4 output lines.
Another page has a voltage/fuel ratio chart showing the output to expect 1.5v at the 14.7 ratio point !?

I actually have only 4 wires coming from these, and they are confusing with a DVM:
Wht B+; Pink 1.85V pretty steady when revving; Grn 7.3v-7.9v revving; Brn 2.24v steady. That makes Pink the best choice?

I have a DEMSI installed on the MAF sensor (no MAP) and I can drop the idle GPM on the Scantron from .35 to .20 GPM and the above Pink line stays pretty constant-thought that would change it for sure!

Ths manual names the downstream sensors HO2S2 (heated O2 Sensors) bank1 and bank2, and the manual states "Under normal conditions the heated oxygen sensor 2 is not used for engine control operation".
It shows a median at 0.73v ranging from 0-0.3-->0.6-1.0v when rich.

What kind of monster have I go here?

(manual pages attached)


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12-13-2009 07:24 PM
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mike Offline
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RE: 1.5v Upstream Sensor in Nissan Frontier
First of all, I'm assuming you have read the directions for your EFIE. The index for EFIE instructions can be found at http://www.fuelsaver-mpg.com/install.html

Wide band:
Find the correct instructions for your device there. For the wide band, front sensors, you'll need the wide band instructions. The 6 wire sensor, is actually for a 5 wire wide band, but with an added 6th wire used as an additional signal ground wire from the ECU. It will read 0 volts. Otherwise it is the same as a 5 wire wide band as described in the instructions. You are not looking for an "output" wire. You are looking for the current pump wires. There are 2 of them, and one has a higher voltage. Or if you find a wiring diagram, it will be labeled as "current pump +", or perhaps "IP+". The instructions tell you how to locate the current pump pair and which wire to install the EFIE on. If all else fails, you can get a wiring diagram for your vehicle from ahdol.com.

Downstream - narrow band:
You downstream sensors are standard narrow band sensors. Even though it says that the downstreams are not used "under normal conditions", they probably are. If you don't have an analog EFIE on them, you will likely get some trouble lights after you treat the upstream sensors. For those 2 sensors, the signal wire will be the one that is changing from "0-0.3-->0.6-1.0v". Install as per the instructions for analog, narrow band EFIEs.

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12-14-2009 08:38 AM
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Mik3h Offline
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RE: 1.5v Upstream Sensor in Nissan Frontier
Thanks, Mike!
I totally agree with the eval of the downstream sensor.

So you believe the upstream is a wide band because of the voltages even though there are only 4 wires coming out of it and none are ground? I might need another EFIE!

I accidently omitted the diagram of the A/F wiring that shows one B+ line from the power buss and 5 lines to the PDU that led me to believe that this model did not actually have an A/F as the upstream sensor since I only have 4 wires from the sensor.
The A/F sensor diagram is now attached-showing it is supposed to have 6 wires if it is an A/F sensor.

(correction on "voltage/fuel ratio chart showing the output to expect 1.5v " - it really states that this 1.5v is 'computed' by the ECM from the A/F sensor1 signal, and is not a 'measured' voltage - according to the P335 document)
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12-14-2009 11:41 AM
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mike Offline
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RE: 1.5v Upstream Sensor in Nissan Frontier
That helps, but it's still unclear. The designations are not standard ones, and there's no key to help us.

You can rule out wires 3 and 4, because those are heater wires. Probably also wire 5 because it has a "V" or "voltage" designation, but this isn't certain. My best guess is that the current pump wires are 2 and 6, but you would have to measure them. One of the last 4 wires (1, 2, 5 & 6) should have 0 volts on it. This would then also be able to be ruled out. You have to measure these with the engine running.

Another trick is to test the wire voltages with the ACC key in the "on" position but the motor not running. Measure the 4 wires then too. The voltage output wire (the one we DON'T want), will have a much different voltage than when the engine is running. This will leave the 2 current pump wires as the only 2 in the correct voltage range. (between 2.3 and 3.3 volts). Once you've found that pair of wires, the higher of the 2 voltages is the one you want. It should be about .300 mv higher in voltage. That's the one that you connect the EFIE to.

Note, you can stick a pin in the wire to measure the voltage without stripping the insulation.

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12-14-2009 12:05 PM
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Mik3h Offline
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RE: 1.5v Upstream Sensor in Nissan Frontier
(12-14-2009 12:05 PM)mike Wrote:  That helps, but it's still unclear. The designations are not standard ones, and there's no key to help us.

You can rule out wires 3 and 4, because those are heater wires. Probably also wire 5 because it has a "V" or "voltage" designation, but this isn't certain. My best guess is that the current pump wires are 2 and 6, but you would have to measure them. One of the last 4 wires (1, 2, 5 & 6) should have 0 volts on it. This would then also be able to be ruled out. You have to measure these with the engine running.

Another trick is to test the wire voltages with the ACC key in the "on" position but the motor not running. Measure the 4 wires then too. The voltage output wire (the one we DON'T want), will have a much different voltage than when the engine is running. This will leave the 2 current pump wires as the only 2 in the correct voltage range. (between 2.3 and 3.3 volts). Once you've found that pair of wires, the higher of the 2 voltages is the one you want. It should be about .300 mv higher in voltage. That's the one that you connect the EFIE to.

Note, you can stick a pin in the wire to measure the voltage without stripping the insulation.

               
Now that I have the correct pages for the 4.0 L version, the readers can see the right diagrams.
Please note that the pages in the 200-400 range are for a smaller engine.

The newer diagrams show Bank1: LG wire to ECMp56(A/F-1), Org wire to ECMp35(A/F+1);
Bank2: Pnk wire to ECMp75(A/F-2), Brn wire to ECMp16(A/F+2)
The data pages describe p35 and 16 as the signal lines varying around 1.8vdc with the A/F ratio, and state p56 and p75 are at approx. 2.2vdc.

Connecting the WB EFIE to p35 and p16 got me only a slight engine load rotating the pot all the way to max.
It does shudder a little after 3/8 turn or so up to max. I can almost kill it just with the DEMSI on the MAF sensor!

Disappointed with that, I tried the other wires (p56 and p75) and saw almost no affect at all.

Getting out the big gun - an oscilloscope, I found:
Grn to ECMp2 and Grn to ECMp43 have Battery Voltage w/a 50 mv squarewave signal on top of it (htr)
LG to ECM56 and Pnk to ECM 75 have 1.8vdc steady w/no A/C component
Org to ECMp35 and Brn to ECMp16 have 2.4vdc with a 100mv signal riding on it, 40ms wide. (idle)
Wht on sensors have a clean battery voltage reading (not connected to ECM).

Soooooo, in spite of the documents showing the reference line at approx. 2.2vdc and the signal line moving around 1.8vdc, I seem to have the signal on the lines with the higher 2.4vdc reading.
Adjusting the EFIE min to max does not appear to change the output as read on a dvm.
What could that mean?

I also added a Dual NB EFIE to the two rear HO2S2 sensors and with 2.2vdc offset left the 'trim' reading on a ELM327 OBDII scanner reporting 0.0% at idle (from -13.3% at full rich with no enhancers enabled)
(This post was last modified: 01-06-2010 10:04 PM by Mik3h.)
01-06-2010 09:10 PM
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mike Offline
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RE: 1.5v Upstream Sensor in Nissan Frontier
First of all, I'm assuming that you know that "Air Fuel Ratio" sensors are another name for wide band oxygen sensors. And also that you have since purchased one of our wide band EFIEs since that first post. If not, that's what you'll need to treat the sensors that are in the diagrams from your last post.

This is real simple now. I don't know what your documents are talking about in terms of a signal wire. But you have a current pump pair, and this diagram shows which they are. Those are the ones prefixed by "AF+" and "AF-". You want the one labeled AF+, and they were around 2.2 volts or so from your measurements. Connect the output of the wide band EFIE to the AF+ wire of each upstream AFR sensor.

Now, you won't see any results on a DVM. You'll only see results if you put an amp meter in series between the EFIE and the AF+ wire. The meter will need to be able to read very small amperages because when the EFIE is turned up to it's max setting (fully clockwise on the pot), the total amperage will be 1.5 milliamps. If the pot is turned counter clockwise all the way, then the reading will be 0 milliamps. I just don't think a voltage change would be detectable, and if it was, I don't know what it would be. We don't deal with voltages on a wide band, only current.

So hook up to the 2 AF+ wires and turn your pot to about 1/3 and see what happens with your mileage. You should be able to make adjustments and get the engine to change its idling characteristics, but this isn't always the case. Sometimes the idle fuel injector pulse width won't change, depending on how the ECU was programmed.

Your downstream sensors appear to be acting normally. Just install an narrow band EFIE on it (or them), and set it to add about .2 volts or so. Maybe try .25 volts. Install it per the instructions for narrow band EFIEs as they are wired differently than wide bands.

Don't worry. You're on solid ground here. There's nothing unusual about these sensors. The only think that's a little unusual is that this is the first time I've seen 4 wire wide bands used on a vehicle other than a Toyota. But, I've been expecting to see more 4-wire wide bands get used because it's the most efficient design or the wide band variants.

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01-07-2010 12:06 PM
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Mik3h Offline
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RE: 1.5v Upstream Sensor in Nissan Frontier
(01-07-2010 12:06 PM)mike Wrote:  First of all, I'm assuming that you know that "Air Fuel Ratio" sensors are another name for wide band oxygen sensors. And also that you have since purchased one of our wide band EFIEs since that first post. If not, that's what you'll need to treat the sensors that are in the diagrams from your last post.

This is real simple now. I don't know what your documents are talking about in terms of a signal wire. But you have a current pump pair, and this diagram shows which they are. Those are the ones prefixed by "AF+" and "AF-". You want the one labeled AF+, and they were around 2.2 volts or so from your measurements. Connect the output of the wide band EFIE to the AF+ wire of each upstream AFR sensor.

Now, you won't see any results on a DVM. You'll only see results if you put an amp meter in series between the EFIE and the AF+ wire. The meter will need to be able to read very small amperages because when the EFIE is turned up to it's max setting (fully clockwise on the pot), the total amperage will be 1.5 milliamps. If the pot is turned counter clockwise all the way, then the reading will be 0 milliamps. I just don't think a voltage change would be detectable, and if it was, I don't know what it would be. We don't deal with voltages on a wide band, only current.

So hook up to the 2 AF+ wires and turn your pot to about 1/3 and see what happens with your mileage. You should be able to make adjustments and get the engine to change its idling characteristics, but this isn't always the case. Sometimes the idle fuel injector pulse width won't change, depending on how the ECU was programmed.

Your downstream sensors appear to be acting normally. Just install an narrow band EFIE on it (or them), and set it to add about .2 volts or so. Maybe try .25 volts. Install it per the instructions for narrow band EFIEs as they are wired differently than wide bands.

Don't worry. You're on solid ground here. There's nothing unusual about these sensors. The only think that's a little unusual is that this is the first time I've seen 4 wire wide bands used on a vehicle other than a Toyota. But, I've been expecting to see more 4-wire wide bands get used because it's the most efficient design or the wide band variants.

Thanks for the quick reply, Mike.
In my post, the 'WB EFIE' is an analog Wide Band Dual EFIE made for the A/F sensors.
Therefore, when I say I connected to ECM p35 and p16, I meant a 'Y' off to the EFIE.
The rear ones are fed thru (cut/re-direct) a potted Narrow Band dual EFIE and the results were exactly as stated in the documents. I have them set to +.22v. That took the 'trim' readings on the ELM327 readout from -13.3% (full normal rich) to 0.0% and I figured that was enough to start with.

I'm just not seeing a mileage improvement with it adjusted about 1/3 CW, where it starts making the engine vibrate a little. The vibration does not increase nor can I kill the engine as I rotate the pot all the way CW. (!?)
Should I disconnect the rear HO2S2 sensors and maybe the MAF sensor (that pops a code) to force regulation only by the A/F sensors, disconnect the battery for 30 minutes, and start adjusting again?
Even if I don't have enough HOH running to make it really lean out (1L/6 minutes), I should be able to make it really buck to tell it is affecting operation?
I'll put it near 1/2 CW for the 13 mile drive home and watch the scantron 'instantaneous output' and Nissan built-in 'average mpg' readout.

And thanks for the DVM readout education!
01-07-2010 02:38 PM
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mike Offline
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RE: 1.5v Upstream Sensor in Nissan Frontier
(01-07-2010 02:38 PM)Mik3h Wrote:  In my post, the 'WB EFIE' is an analog Wide Band Dual EFIE made for the A/F sensors.
Therefore, when I say I connected to ECM p35 and p16, I meant a 'Y' off to the EFIE.

I'm just not seeing a mileage improvement with it adjusted about 1/3 CW, where it starts making the engine vibrate a little. The vibration does not increase nor can I kill the engine as I rotate the pot all the way CW. (!?)
Should I disconnect the rear HO2S2 sensors and maybe the MAF sensor (that pops a code) to force regulation only by the A/F sensors, disconnect the battery for 30 minutes, and start adjusting again?
Even if I don't have enough HOH running to make it really lean out (1L/6 minutes), I should be able to make it really buck to tell it is affecting operation?
I'll put it near 1/2 CW for the 13 mile drive home and watch the scantron 'instantaneous output' and Nissan built-in 'average mpg' readout.

And thanks for the DVM readout education!

OK. I'm assuming you're talking about the Dual Wide Band EFIE Basic from FuelSaver-MPG.com. Also, I think you have a typo because the terminals you should be using are p36 and p16, per the diagrams you attached. Is that the ones you're using? Note, my copy is pretty small and while it looks like it says "36", it may be "35" and I just can't tell the difference between a 5 and a 6. Just make sure your using the wire marked "AF+1" and "AF+2". And to be real sure, make sure that they are about .3 volts or so higher than the corresponding "AF-" terminals. That will make sure you're on the correct wires.

Many vehicles have ECUs programmed to not let the injector pulses drop below a certain minimum amount at idle, so not all cars will lug down and eventually die with the sensor adjustment. They just don't all do that. So that doesn't mean there's a problem with your installation. So, you can't expect the engine to buck from the use of these devices. The ECU often will not allow this to happen no matter what you do with the sensor data.

Do not disconnect the MAP or the downstream sensors. This is not the correct way to solve the problem, and will likely put the car into open loop and your mileage will get worse than before you started.

Lastly, if you're only making 1/6 LPM of HHO, you now need to get a hydrogen generator that is sized for your vehicle. That's just not enough, and trying to improve mileage with an EFIE only is not only not recommended, but very difficult to do. So, after checking that you're on the right wire as described above, your next step is to get your hydrogen debugged.

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01-08-2010 10:12 AM
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Mik3h Offline
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Post: #9
RE: 1.5v Upstream Sensor in Nissan Frontier
Yeah, I tried expanding the files I left on the site and they are kind of hard to read as they get fuzzy. Anything else I leave will be better quality if you don't have a document size limitation.
My Dual Wide Band EFIE Basic is connected to the AF+1 and AF+2 lines, the Org and Brn ones. I'll double check that.
The only thing I've seen on HOH volume needed was on a blog here where someone said a minimum was 1/2 L/min per L of engine size. I don't remember the max stated, the paperwork is at home.
Therefore, I guess for a 4L I need a dry cell to get 2 L/m output.
I'll research more on the W4G Jars using NaOH or KOH to keep it away from boiling at higher outputs.
BTW readers-note in post #5 above that the statement "The data pages describe p35 and 16 as the signal lines varying around 1.8vdc with the A/F ratio, and state p56 and p75 are at approx. 2.2vdc." has the voltage values reversed from what I actually measured. The signal lines are the ones labeled that, but the + signal line has the 2.2vdc and the - line has the 1.8vdc
01-08-2010 11:55 AM
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mike Offline
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RE: 1.5v Upstream Sensor in Nissan Frontier
There is a doc size limitation. But I wasn't complaining. Just expressing that I might have been mistaken on my number. It seemed possible that I was misreading it.

Actually, I got the formula from Bob Boyce personally. It is actually 1/4 to 1/2 LPM per liter of engine displacement. You don't need 2 LPM for a 4 liter engine. You need 1 to 2 LPM for a 4 liter engine. 2 LPM would be the highest amount you should use.

Now the only thing I would add to that is that Bob was talking HHO from a good system that didn't make alot of stream. Some systems are run so hot that we call them "steamers", and their volume can be quite high, while producing very little actual HHO. So just bear that in mind. If the cell runs at 100 degrees or so, and is still producing over 1 LPM, then you are in good shape.

Thanks for the clarification on the voltages. That makes it all make sense now.

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01-08-2010 05:45 PM
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