o2 readings

[Bob Valentine]

I've noticed that single-wire 02 (for gm, at least) seems to work OK with
just a high-impeadance DVM, while the heated 02's I've tried (ford, mopar)
have the low-output symptoms when not hooked to a ECM.

Not sure why, just an observation.

-> Bob Valentine
-> bob at tecmark.com

At 06:47 PM 1/1/2001 -0800, you wrote:
>Thinking out loud here.....sounds like you have just recently added this O2
>sensor to your conventional carb'd quadrajet setup, and that the O2 sensor
>is not now (nor has it ever been) a part of a computerized feedback loop?
>Also, with what are you measuring the small O2 sensor voltages, and what is
>that device's input impedance?  Normally, a feedback O2 sensor (conventional
>zirc) would be part of a larger signal conditioning circuit within a
>computer, and would superimpose small voltages overtop a 450mv carrier
>signal.  I'm not entirely sure what you would observe if you were to measure
>the raw unconnected O2 sensor output voltages with say a normal DVOM.
>Perhaps someone else has tried this and can relate to your numbers.
>
>As for the wiring of your sensor, use your DVOM to check continuity from red
>to black and then red to grey (you later called that one white).  Whichever
>combo has the least resistance is your heater circuit pair.  The remaining
>wire (probably the grey) will be your signal wire.  To measure the resultant
>output voltages, you'll need to connect your test device from the signal
>wire to the shell of the O2 sensor.  Your test device had better have at
>least 10 Mohm input impedance, with closer to 100 Mohm being best (as per
>Fluke's published data).
>
>Walt.
>
>
>
>
>
>
>> the o2 sensor is a Sorensen 779-7020, I bought it some time ago and just
>had
>> a bung welded in.
>>
>> I do not know if this is from a gm tpi application or not, I thought that
>> they were all pretty much the same.
>>
>> does the wiring I have look right ? red=+12v, black = gnd, and white is
>the
>> sensor ?
>>
>> it varies between 11.09 at idle up to 36 mv with partial throttle. It
>takes
>> about 45 seconds or less for it to warm up and give me some readings.
>>
>> thanks, Diane
>>
>> thanks, Diane
>> ----- Original Message -----
>> From: "Programmer" <nwester at eidnet.org>
>> To: <gmecm at diy-efi.org>
>> Sent: Monday, January 01, 2001 3:30 PM
>> Subject: Re: o2 readings
>>
>>
>> > You're using a 3 wire heated ? Ok--happen to have the part number
>> > handy ? With the numbers that low, the ECM is going to command
>> > longer pulse on the mixture control solenoids--and go full rich.
>> >
>> > Lyndon.
>> > -----Original Message-----
>> > From: Diane Stowe <dianes at speakeasy.org>
>> > To: gmecm at diy-efi.org <gmecm at diy-efi.org>
>> > Date: December 31, 2000 2:14 PM
>> > Subject: o2 readings
>> >
>> >
>> > >Hello, a question. I thought I would test my newly installed 02 sensor
>> > prior
>> > >to my installing the new map tpi. I have a quadrajet on it now.
>> > >
>> > >I presumed that the red and black were 12v+ and -, and that the gray
>lead
>> > >was the sensor reading. The sensor is welding in a bung that is about
>5-6
>> > >inches below the passenger side exhaust manifold.
>> > >
>> > >anyway, with 12 to the o2 heater, which is on all the time, I get 11mv+
>> at
>> > >idle and somewhere between that and 36+ mv on driving up hills or
>> > >strightaways.
>> > >It never goes below that, or negative. Is this what I should be seeing
>?
>> my
>> > >rpm never gets above 2300 due to the 700r4 and the 2:88 rear I have in
>> the
>> > >car. I am trying to track down the cause of the poor fuel mileage, it's
>> > >about 10 mpg. that with a custom grind crower street cam, a new timing
>> > >chain, a edelbrock performer and recently 21/2 inch pipes from the
>> exhaust
>> > >headers to the front mufflers and the installaiton of a crossover pipe
>> > after
>> > >the transmission. sadly none of these changes have helped much. I'm
>> > assuming
>> > >that the quadrajet is just running too rich, however I am not sure from
>> > >these readings.
>> > >
>> > >thanks, Diane
>> > >
>
>
>----------------------------------------------------------------------------
>To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
>in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>
>
----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org