O2 sensor at 5,00 volt constantly?

[EuroGSTSpyder]

Ok I had a bad sensor I am sure since I got really weird values on emission and also smelled gas behind the car when runing..SO I got a replacement sensor , universal one, cut the cables at correct length. Took the stock one and removed the connector pins fro minside the plastic connector. Soldered the pins on to the new harness and the put them back in the plug.

Everything seemed to work fine but Now when I am driving the O2 sometimes fluctuates between 0,1-0,9 roughly ...wich means it works right? BUT...it also goes up and holds at 5.00 volts according to logger...What is going on? Is there a glitch in the connector? Is the new one fried already? How comes it reads 5.0 if its not connected, shouldnt it read 0.0 then?

Help me out casue I need to fix this this weekend if possible

 

[Mikelb]

Standard O2 sensors shouldn't read more than 1 volt. I'm guessing you have a short somewhere.

Wideband O2's read 0-5V. Maybe there's a setting in your logger that you need to change for a standard O2 sensor.

 

[laserspeeddemon]

Did you remove the ground strap from the exhaust?

 

[EuroGSTSpyder]

nope strap still there

My logger is a regular pocket logger from obdlogger.com.
It does read correct ...and then goes to 5.0..then it might start read again..and then go back to 5.0.


Will pull it tomorrow and see if I can find any faulty wires on it....

 

[laserspeeddemon]

I dunno man. I haven't run into that problem. I can understand it going to 0.98v when under full throttle but 5v?

Is this your 1g?

 

[EuroGSTSpyder]

yuppers, it my 91 tsi awd.Weird s**t

 

[Mikelb]

Sounds like a short to the O2 sensor. if it reads correct sometimes, then goes to 5V (same value as when the O2 isn't present).

Check the wires.

 

[laserspeeddemon]

Sounds like a short to the O2 sensor. if it reads correct sometimes, then goes to 5V (same value as when the O2 isn't present).

Check the wires.

In conjuction with this statement. Try disconnecting the 02 sensor and see what reading you get. I thought you would get 0v, because the voltage is created by the presence of fuel, not the absence of it. Thus if you disconnect the mechanism responsible for producing it, then it should return 0v.

The oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage (see the patents below for details). The engine's computer looks at the voltage to determine if the mixture is rich or lean, and adjusts the amount of fuel entering the engine accordingly.

 

[Mikelb]

In conjuction with this statement. Try disconnecting the 02 sensor and see what reading you get. I thought you would get 0v, because the voltage is created by the presence of fuel, not the absence of it.


Quote:
Originally Posted by www.howstuffworks.com
The oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage (see the patents below for details). The engine's computer looks at the voltage to determine if the mixture is rich or lean, and adjusts the amount of fuel entering the engine accordingly.

I fully understand what you are saying. I realize what O2 sensors do, but in the first post
EuroGSTSpyder said

Everything seemed to work fine but Now when I am driving the O2 sometimes fluctuates between 0,1-0,9 roughly ...wich means it works right? BUT...it also goes up and holds at 5.00 volts according to logger...What is going on? Is there a glitch in the connector? Is the new one fried already? How comes it reads 5.0 if its not connected, shouldnt it read 0.0 then?

So, it's showing 5V when the O2 sensor isn't there. That means, this is most likely a short somewhere in the circuit.

 

[EuroGSTSpyder]

I havent removed the connector..I meant in my post that if there is a glitch IE it doesnt connect at all , would it then be 5.0? I would think as stated above that if the ECU looses conncetion with the sensor that it would drop to 0, not go to 5.0.

I will try to unconnect the sensor and see what I get.

Short..yes possible but I cannot se how since its a brand new sensor and the wires are covered by a plastic tubing just like the one was before IE stock. Maybe something has happened though..will check and see what I can come up with. Thanx for helpin though guys..keep it commin

 

[Mikelb]

I'm sorry, the way I read it was that you had disconnected it.

Yes, with the O2 disconnected, it should read 0 though.

 

[laserspeeddemon]

Even if you matched the wires by color, they could have different fuctions. This especially apparent with stereo installs. Just an FYI.

 

[EuroGSTSpyder]

update:
Disconnected the sensor and logger goes right back to 0,0. Plug it in again and it shows 5.00 directly so yes there is somethin wrong with the sensor or the wiring.

LASER: If it was wired wrong it shouldnt be flutuating correctly from time to time I guess? When it does connects it seems to read correctly cause it is between 0,8-0,94 then...
Will have to check it out thouroughly or buy a OEM to see if it helps.
Maybe this is why I got high HC values on emissions as well...but then..then wouldnt the lambda be correct. weird car**

 

[laserspeeddemon]

Not really, since you have a heated 02 sensor from the factory. I don't know how you wired it so I can't be sure, but if you some how wired the the reading sensor into the heating wiring, then it would shoot straight up since the voltage for the heater is 12v (5v may be at it's mechanical limit).

The other more obvious and overlooked problem is they sold you a faulty 02 sensor.

 

[EuroGSTSpyder]

wires stock are two black one blue and one white. Sensor I bought had the same colour wirings. Switched in the connector one by one so the pins got the correct wire to the correct pin. Then it worked for a few days but now its gone again...maybe the sensor, maybe something else. Weird anyways....will pull it again and see what I can find out.

 

[spyderturbo007]

What logger program are you using? You might have it set in 3000GT mode, or you might be looking at the wrong O2 sensor.

 

[EuroGSTSpyder]

digitaltunings pocketlogger program.

I am 1g so I only have one sensor, but I will ceck with the logger again to see what up. Still, it will not affect the values of the exhausts on the car since I only log it, not change it. My HC values were through the roof

 

[EuroGSTSpyder]

Ok problem with the sensor solved....
Looked at it today and found that right next to the sensor the cables has melted together for some reason. About half an inch of the cables were merged so they shorted out.
Separated them and the sensor seems to have made it, its reading just fine now.
I jusdt have to tape them up and make sure the protection cover on the cables are all the way down to the sensor.

Could this have caused the fact that my HC readings were way high on emissions? It would have been all wrong in fuel mixture due to this I assume wich cause it to dump unburnt fuel in the exhaust?

 

[laserspeeddemon]

Correct. When part of your fuel system is damaged or sending erroneous data, the ECU switches to a base map, which is setup to run rich. Mitsubishi designed it this way so in order of a failure it rather hurt the cat (by clogging it with a rich mixture) then the engine (piston failure due to lean mixture).

I would drive the car for a little before getting test, as left over residual fuel may still me in the cat, and you would fail again.

 

[EuroGSTSpyder]

will try to get out and drive some , but the car is banned from the streets til emissions passes so..I will have to go "stealth to avoid detection" **

Anyways..I will go out and drive some and see how everything goes..if the trims goes back to 100% and also try to borrow a friends emissions stuff at his work and meassure the car up.

Thanx all

 

[spyderturbo007]

I am 1g so I only have one sensor, but I will ceck with the logger again to see what up.

Ooops. I saw your avitar and assumed it was the 2g Spyder we were talking about.

 

[Doug99RS]

If I looked at the wiring diagram right, even though it's a 91 it's still a heated o2 which has 4 wires going to it. Meaning that it uses battery voltage of 12 volts to heat the o2 and the o2 itself is a voltage generating defice. Most other sensors use 5 volts as a reference voltage to go through a resistor that is part of the sensor and the balance of the voltage is sent back to the ECU to determine the temperature, position or pressure which indicates that sensors attitude. So, be that as it may, if it's internally shorted I cannot see how it's going to short exactly the same as a reference voltage.

I would be more inclined to say that you've got a reference wire that has shorted to your o2 signal wire OR possibly you've got corrosion on your ECU circuit board causing false reading on one or more sensors and the o2 just happens to be the one you've managed to catch.
Doug

 

[laserspeeddemon]

If I looked at the wiring diagram right, even though it's a 91 it's still a heated o2 which has 4 wires going to it. Meaning that it uses battery voltage of 12 volts to heat the o2 and the o2 itself is a voltage generating defice. Most other sensors use 5 volts as a reference voltage to go through a resistor that is part of the sensor and the balance of the voltage is sent back to the ECU to determine the temperature, position or pressure which indicates that sensors attitude. So, be that as it may, if it's internally shorted I cannot see how it's going to short exactly the same as a reference voltage.

I would be more inclined to say that you've got a reference wire that has shorted to your o2 signal wire OR possibly you've got corrosion on your ECU circuit board causing false reading on one or more sensors and the o2 just happens to be the one you've managed to catch.
Doug

We already found the problem NOOB!

 

[Doug99RS]

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