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Eduardo Castrejón Elbjorn's Avatar
 
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Question 02 sensor

1984 auto

Hi to everyone !

Yesterday I worked on my 944

I already install the cam housing,belts, injection, the engine is running and appears to be ok, I don´t have more oil and air leaks !, at last
I´m happy.
Thanks to everyone for your help, I can´t did it with out this great forum !

I already use the 02 sensor to calibrate my new maf (C02)

My actual problem is:

I bought this car with yunk o2 sensor and unconnected, then I already replace the 02 sensor.

I want to check if the dme is reading the 02 sensor , How I can do it ?

Let me know
Regards
Old 05-08-2003, 09:25 AM
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I may not understand correctly, so if this doesn't make sense let me know. Unhook the O2 sensor. Then adjust the fuel mixture untill the O2 sensor reads over 1-1.2 volts constantly. Reconect the O2 sensor and check the voltage. The O2 sensor should read less voltage as it leans the mixture out. This will show if the DME is processing the O2 sensor signal.
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Old 05-08-2003, 09:34 AM
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Outstanding about the oil leaks. Good job, Ed!
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my web site Torque values maintainance and repairs lots of my rebuild pics weights and measurements
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Old 05-08-2003, 07:41 PM
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You can not measure the o2 readout while it's connected to the DME unless you have a high quality air/fuel gauge, or your voltmeter has shielded wires coming, is very accurate, and doesn't disturb the signal.

The readout is under 1 volt if I remember correctly. I would check the readout @ the DME, as this would tell you if the signal reaches the DME and if so what it reads. If I remember correctly, it should be pin # 24.
Ahmet
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Old 05-08-2003, 10:24 PM
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Thanks for your answers

Quote:
I would check the readout @ the DME, as this would tell you if the signal reaches the DME and if so what it reads. If I remember correctly, it should be pin # 24.
That is exactly I want, please let me know

regards
Old 05-09-2003, 07:32 AM
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also lots here that o2 testing:

http://frwilk.com/early944/co_level.htm

and this:

http://frwilk.com/early944/misc/oxygen.htm

but not as easy on with the 3 wire sensor...don't think yours is 3 wire anyway
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Old 05-10-2003, 06:33 AM
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Thanks Carsontc:

Yes, I followed this instructions before I post my answer.

I don´t have problems installing or measuring the co2 with the 02 sensor.

I only want to test if my dme is reading or not the o2 sensor.

Then I want to know if somebody can tell me the know how of how to read the o2 sensor by the dme ?
Old 05-10-2003, 08:19 AM
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I think what Roger was implying was by just disconnecting the o2 sensor you should notice a definite change in the way the engine runs...proving the DME is at least reading the o2 and doing something with the information...(assuming the o2 sensor is sending a voltage signal)
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Old 05-10-2003, 08:34 AM
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Quote:
I think what Roger was implying was by just disconnecting the o2 sensor you should notice a definite change in the way the engine runs...proving the DME is at least reading the o2 and doing something with the information...(assuming the o2 sensor is sending a voltage signal)
Yes, but I spend a lot of time calibrating my maf to now change the setting !
In this moment I don´t have change if I connect or disconnect the sensor but probably (I want to believe ) is because is almost stoichometric.

But if I don´t have an answer to how to check the 02 sensor by the dme I will do it.

In this moment I´m waiting for a new cone air filter then I will need to adjust again soon and I will take the oportunity to do it.
Old 05-10-2003, 08:58 AM
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I guess I am still not sure what you want. Are you

Verifing That the O2 sensor is working?
Verify the wiring is correct and that the O2 sensor signal is reaching the DME?
Verify that the system is working to adjust you Air/fuel mixture?
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Old 05-11-2003, 03:33 PM
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Quote:
Verify the wiring is correct and that the O2 sensor signal is reaching the DME?
I wan to know this

regards
Old 05-12-2003, 09:48 AM
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Quote:
Originally posted by 1.2gees

The readout is under 1 volt if I remember correctly. I would check the readout @ the DME, as this would tell you if the signal reaches the DME and if so what it reads. If I remember correctly, it should be pin # 24.
Ahmet
This will work for a single wire O2 sensor. I am not that familiar with the multiple wire sensors.

I am not sure which pin it is on your DME connector. However the O2 sensor will continue to send a signal while it cools down. If you run the car through two or three fan cycles. Then disconnect the connector there should be a voltage reading on that pin. It will continue to drop as the exhaust gases disipate and the O2 sensor cools down. the reading should start out less than 1.2 volts and drop to zero. I would not try jumping or splicing the wire to try and get the readinging while the engine is running. The O2 sensor wire is sheilded and since the signal is less than 1 volt it can be easily altered giving a false reading.
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Roger Hall

81 924 N/A

Some people are like Slinkies. Not really good for anything, but you
still can't help but smile when you see one tumble down the stairs.
Old 05-12-2003, 05:41 PM
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