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Old 05-29-2009, 11:12 PM
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Multi-meter used as a Air/Fuel Gauge??

I was thinking about getting two fuel air gauges with O2 sensors on each bank. That way I could tune the Edelbrock accordingly.

Instead of using gauges can I use a multi-meter? Doesn't the sensor just spit out ohms?

Thanks

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Old 05-30-2009, 08:38 AM
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Quote:
Originally Posted by ryankalel
I was thinking about getting two fuel air gauges with O2 sensors on each bank. That way I could tune the Edelbrock accordingly.

Instead of using gauges can I use a multi-meter? Doesn't the sensor just spit out ohms?

Thanks
I suspect you could, but how do you translate volts to AFR? Why not just buy a gauge?
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Old 05-30-2009, 08:56 AM
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Actually the sensor spits out volts, just like a thermocouple. Here is a link to a long page about holley carbs, if you scroll down about 2/3 you'll find a section about using a VOM with an off the shelf O2 sensor to read A/F
http://www.bob2000.com/carb.htm

When you are scrolling, look for the big graph. the adjacent section tells how it's done.

I don't know how accurate the page is, I never built one of the setups, but I did spend money on one of the LED light A/F gauges, and it sucked.

Later, mikey
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Old 05-30-2009, 12:26 PM
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I also found this site, not sure how accurate, but it seems on.

http://www.datsuns.com/Tech/oxygen_sensors.htm
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Old 05-30-2009, 01:01 PM
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Great link, added to my favorites. The chart with voltage is especially handy.The good part is that for the price of an O2 sensor, a bung found at any muffler shop and either a analog multimeter or good digital multimeter (which most guys already have), or even a stand alone meter that reads millivolts, and with that that you can build a A/F monitor to tune your car, then plug the O2 bung with an old sparkplug or something till you need to set it up again.

The problem I had with the Edelbrock LED A/F readout I had was it wouldn't ever do anything but spaz out from lean to rich and everywhere in between...I tried a bunch of different jets and settings and checked the wiring and O2 sensor and it never gave any indication that it wanted to actually EARN the 120.00 I paid for it.....So I fired it for no call/no shows, denied it unemployment, and threw it out.

How close will it be? It has to be every bit as close as doing a cut and coast from the fastlane, then reading spark plugs on the side of the freeway to tune your carb, and you can always double check your settings afterwards by reading plugs .

I'm actually kind of stoked, I have all that stuff in my junkpile, and I need to tune the 650 on my blazer, I put it on 4 years ago, pulled straight off some junkyard find and I think it's been long enough ...

I know it isn't lean, that's all I can say.

Later, mikey
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Old 05-30-2009, 10:21 PM
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The nice thing about using a voltmeter is if you have a fancy one with graphing capability you could store the results and review them afterwards...not to mention the response speed is very high with no lag.
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Old 05-30-2009, 11:08 PM
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I am glad that there is people up here smarter then me. Not having access to a dyno I have often wondered if there was a way to convert an oxygen sensor in to a tool for jetting. I don't really need it for any of my cars but it would be great on my bikes. In playing around with my old carbureted Harleys it has come to trial and error with a lot of driving on deserted roads and pulling the plugs to read them. This will definitely help.

Thanks for the info!
Chris
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Old 05-30-2009, 11:24 PM
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Quote:
Originally Posted by 4 Jaw Chuck
The nice thing about using a voltmeter is if you have a fancy one with graphing capability you could store the results and review them afterwards...not to mention the response speed is very high with no lag.
I think that having a slower response might help, in at least one of the articles it said if you use a digital meter to make sure it is a good one.

From the article that ryankalel posted.
Quote:
If you use a Digital Multi Meter, you have to use a high quality Digital Multi Meter such as the Fluke 87 due to the high impedance.

The O-2 sensor will respond to changes in air fuel ratio INSTANTANEOUSLY! If you have one cylinder miss fire on just one revolution of the crank, the O-2 sensor will detect it and your Multi Meter or Air Fuel Ratio monitor will show you a spike.
Yeah Chris, I am thinking about hooking up a couple of o2 sensors on my shovel too. I just haven't done it because it will mess up the patina on the pipes...well not all is lost...the one that's painted can always be regreased.

Later, mikey
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Old 05-30-2009, 11:56 PM
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Quote:
Originally Posted by powerrodsmike
I think that having a slower response might help, in at least one of the articles it said if you use a digital meter to make sure it is a good one.

From the article that ryankalel posted.


Yeah Chris, I am thinking about hooking up a couple of o2 sensors on my shovel too. I just haven't done it because it will mess up the patina on the pipes...well not all is lost...the one that's painted can always be regreased.

Later, mikey
Yeah Mikey, that shovel of yours is way kewel!

But what do you think about this. I don't want to mess up my pipes either so do you think that I could put one on the end of a metal rod and then slide it up in the muffler? I would have to use some kind of wire that would be heat insulated. Any thoughts would help.
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Old 05-31-2009, 12:22 AM
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I would think the whole sensor shoved up the ppe would create so much backpressure it would throw the readings off, but I would think you could fab up an adapter for the back of the pipe, with a heated o2 sensor, then take it off after you tuned on it. No dilution would be going on in the pipe, but the gas would cool so much at the back end of the pipe that I would guess the sensor would never heat up properly, hence the need for a heated sensor.. I know the last bike I did a bunch of fab work on had a pipe with O2 bungs welded in it at the first bend out of the head..

The FI fuel management modules they sell in the bike catalogs appear to all use the large O2 sensor. I'm not sure if they make one small enough to shove up a pipe and not mess up the flow.

Later, mikey
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Old 06-02-2009, 05:26 PM
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Okay, so if I made a devise that clamped on to my muffler outlet and it fastened the heated O2 sensor in the middle of the exhaust stream, I would need to use a heated sensor correct? Only problem I'm not familiar with the heated sensors and or how to wire one. Would the readings be the same?
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Old 06-02-2009, 05:53 PM
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In order to do what you are trying to accomplish you will need a wide band O2 sensor. The ones that would come in a Daily driver dont have a wide enough range.
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Old 06-02-2009, 08:28 PM
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If you use an unheated sensor it has to be very close to the exhaust manifold, because the sensor needs high exhaust heat to ensure accurate readings. If you move it out to the header collector, it won't give accurate readings at idle, when there isn't enough heat to keep the sensor stable.

A heated sensor is electrically heated, so it does not depend on exhaust heat. It can be installed in the collector, and should work even if you put it as far back as the tail pipe.

Bruce
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Old 06-02-2009, 11:33 PM
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Quote:
Originally Posted by T-bucket23
In order to do what you are trying to accomplish you will need a wide band O2 sensor. The ones that would come in a Daily driver dont have a wide enough range.
Chet I may be wrong but according to what I just read here
http://www.innovatemotorsports.com/f...hp/t-1578.html
I don't think a wide band sensor would be the way to go. From what I have found it seems as though the only thing that can read the 5 wire wide band is the cars ECM. But if you have a scanner hooked to the data port it will give the readings while the car is running. What we need is an 02 sensor expert to help us figure out which type of heated sensor would be the best and how to wire it. With the little bit of research I have just done I have found out that heated sensors come in configurations of two, three and four wire. Making a devise to hold the sensor at the tail pipe would be no problem. Just a matter of welding up a six inch or so piece of pipe that would clamp to the tail pipe with an air tight fit and it would be able to place the sensor directly in the exhaust flow. No problem. I could do that easy enough. I just need to know which heated sensor to buy and how to wire it.
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Old 06-03-2009, 01:24 AM
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I have a 3 wire o2 sensor and a motor on the test stand and a smog shop next door...
Imma gonna play around some.
I already found out if you hook the 2 wires that have continuity together (both white),the sensor gets hot...very hot. And if you read the voltage between the case and 3rd wire (black), it makes about 1.1 volts ...(by the charts, it should read less than that...more experiments tomorrow)

This is a kind of cool article:
http://mr2.com/TEXT/O2_Sensor.html

Later, mikey
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Last edited by powerrodsmike; 06-03-2009 at 02:22 AM.
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