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O2 sensor output!
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keenman11 Offline
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Post: #1
O2 sensor output!
Mike,
I haven't received my EFIE yet, but how do I determine what reading my O2 sensor is sending the computer right now before I hook it up? Will this reading be the same after I start up my fuel saving HHO device? I understand that the EFIE device reading will be the offset number that it sends to the computer! The total that the computer receives will be this amount plus what it was already receiving. Would this be in millivolts? Would a digital muitimeter show this as 125 mv or .125 mv? I have read almost every post on your site & boy I'll tell you, it moves me to a point of confusion. I have assumed, from reading your device specs that when I do receive my EFIE it will be set at .100 mv or 100 mv. Which of these reading should I see on my multimeter? It gets real confusing when I see the reading sometimes as .250 mv and then as 250 mv. They are ,to me, entirely different numbers. I look at .250 mv as being 1/4 of a millivolt. I am probably totally wrong about this ,but?
(This post was last modified: 02-05-2008 01:47 AM by mike.)
02-04-2008 07:39 PM
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mike Offline
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RE: O2 sensor output!
First, your EFIE shipped on the 2nd, which was a Saturday, and therefore, probably didn't actually go anywhere until Monday. That means that you should get it tomorrow, or perhaps, the next day.

Next, yes, after installing the EFIE the value going to the computer will be the sensor's value plus the voltage added by the EFIE, and that amount is what you set the EFIE to add.

The amount the EFIE can adjust is between approx .020 volts (20 millivolts) and over 500 millivolts. But never go that high, as the computer will think your sensor is malfunctioning and will ignore it's data (and make your mpg go way down).

Per your example, your multimeter will show either .125 Volts, or 125 millivolts. Those are equivalent.

If you see .250 millivolts, someone made a mistake (hope it wasn't me). We don't use values that small ever. It's either .25 volts, or 250 millivolts, which are equivalent values. I'm liable to say either one, depending on what I think the person I'm talking to understands best. If they say .25 volts, then I usually use the same format. If they call it 250 millivolts, I usually also follow suit. But you can know that fractions of millivolts are a typo or something. We never have use for values that small.

Does this make a little more sense?

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(This post was last modified: 02-05-2008 02:35 AM by mike.)
02-05-2008 01:43 AM
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keenman11 Offline
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Post: #3
RE: O2 sensor output!
mike Wrote:First, your EFIE shipped on the 2nd, which was a Saturday, and therefore, probably didn't actually go anywhere until Monday. That means that you should get it tomorrow, or perhaps, the next day.

Next, yes, after installing the EFIE the value going to the computer will be the sensor's value plus the voltage added by the EFIE, and that amount is what you set the EFIE to add.

The amount the EFIE can adjust is between approx .020 volts (20 millivolts) and over 500 millivolts. But never go that high, as the computer will think your sensor is malfunctioning and will ignore it's data (and make your mpg go way down).

Per your example, your multimeter will show either .125 Volts, or 125 millivolts. Those are equivalent.

If you see .250 millivolts, someone made a mistake (hope it wasn't me). We don't use values that small ever. It's either .25 volts, or 250 millivolts, which are equivalent values. I'm liable to say either one, depending on what I think the person I'm talking to understands best. If they say .25 volts, then I usually use the same format. If they call it 250 millivolts, I usually also follow suit. But you can know that fractions of millivolts are a typo or something. We never have use for values that small.

Does this make a little more sense?
In your 3rd sentence above, :
(1) As I understand it, The value displayed on my EFIE screen (after being hooked up) will be my O2 sensor output value + my EFIE offset value?
(2) How do I check what my O2 sensor output value is (after it is warmed up), on my multimeter, before I hook up my EFIE?
(3) Will this O2 sensor output value, being read on my multimeter at this time, be the same after I start up my HHO unit, before I turn on my EFIE?
(4) The O2 sensor senses the amount of oxygen in the exhaust and outputs a number to the computer in millivolts, is this statement correct?
(5) Will all of the numbers I'm looking at on the EFIE screen be in averages?
(6) Will all of the numbers I'm looking at on the multimeter (I have a Radio Shack digital multimeter) be in averages?
02-05-2008 09:53 AM
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mike Offline
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RE: O2 sensor output!
1. You seem to have a misunderstanding about the EFIE. It doesn't have a screen. It has 2 ports that you can plug your multimeter leads into, and you then can read it's voltage offset from your multimeter.

Many of your questions are answered in this article. Please write back if you don't understand something in it. But it goes into the voltages you will read with your meter hooked up to various points on the EFIE and your vehicle.

2. I don't know how to check this voltage with a multimeter. The trouble is that the oxygen sensor voltage is constantly changing, swinging from very low to very high multiple times per second. Your multimeter will only be able to show you an average, or possibly it will just give the voltage it reads at a particular instant in time. Regardless you will see a constantly changing voltage. Please note, that this is the oxygen sensor signal wire measured against ground.

3. If you could perceive the difference (which you can't as per #2 above), you still wouldn't see a difference. The reason is that while there will be more oxygen in the exhaust, the computer will adjust the amount of gas going in to compensate for that. Therefore, the sensor output will be the same. What will change is the amount of fuel being dumped into the engine by the computer. If you were able to read the electronics going to your fuel injectors, then you'd see the change there.

4. Yes, that statement is correct.

5. Already answered.

6. I'm not sure exactly. It could be averages, and it could be instantaneous voltages at it's sample rate (usually once or twice per second). I actually have never dug into how the multimeters deal with a source that has voltage fluctuations like this.

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02-05-2008 10:59 AM
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keenman11 Offline
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Post: #5
RE: O2 sensor output!
Mike,
The article you refered me to now makes sense. Thank you!
02-05-2008 11:38 AM
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qsiguy Offline
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RE: O2 sensor output!
Sounds like you have a good grasp on the details now. I just have one thought on the subject of reading the sensors output. If you really want to "see" exactly what the sensor is doing in real time you could try an analog meter. It will give you a needle that will move up/down as the sensor voltage rises/falls. The narrow band gauges available to read a/f ratios will show this fluctuation real time. I have one of these in my turbo car. Not really a useful gauge for determining your a/f ratio but it does show you when the ECU is in open or closed loop and it does show that the O2 sensor voltage is rising and falling as it should.

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02-06-2008 09:06 PM
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mike Offline
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RE: O2 sensor output!
I've wondered about an analog meter. Probably have to get it at a second hand store, or garage sale or something. Have you tried it? I was wondering if the needle movement would be able to keep up.

I did make a set of 10 leds that light up at .08 volt increments from .1 to .9 volts. That was quick enough so that you could see the activity. It doesn't tell you much, but it looked cool.

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02-07-2008 02:30 AM
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qsiguy Offline
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RE: O2 sensor output!
Analog meters are still sold. I saw a couple at Ace Hardware the other day. It was a pretty decent one but was a little spendy if you only want it for this. I see little cheapo ones at stores like Walmart all the time. Harbor Freight Tools will have some probably. Here's a few links to check out.

Not sure if it's still available...
http://www.harborfreightusa.com/usa/item...egoryName=

Ace Meters...
http://www.acehardware.com/product/index...age=family
http://www.acehardware.com/product/index...age=family
http://www.acehardware.com/product/index...age=family
http://www.acehardware.com/product/index...age=family

I have this one..
http://www.acehardware.com/product/index...age=family

I tried searching the Walmart site but they don't have them listed. I know I've seen them there. I can't say I've tried my analog meter on the o2 sensor wire. I have 2-3 of them around, just don't use them very often. I'll try it and post results before anyone goes out and buys one. The bummer is you can get decent digital meters cheaper than all of these.

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(This post was last modified: 02-07-2008 09:39 AM by qsiguy.)
02-07-2008 09:32 AM
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mike Offline
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RE: O2 sensor output!
Yes, plus digital meters basically just rock. It's like using a calculator vs using a slide rule. I learned how to use a slide rule once. I doubt I could do it now, but a calculator is more accurate and much easier to use.

Anyway, thanks for the links. If you get a chance, see what it reads for you. It's pretty easy to test, now that you have your EFIE installed. See if you can perceive the difference between the sensor and computer ports (vs ground).

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02-07-2008 11:32 AM
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qsiguy Offline
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Post: #10
RE: O2 sensor output!
I haven't got my EFIE installed yet but did wire up the analog meter to the O2 sensor wire at the ECU. It does show the pulses quite well.

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02-09-2008 09:21 PM
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