How to test my oxygen sensor??

[eclipse0508]

Hey everyone

I have a 95 eclispe gs, with CAI, header w/downpipe and mozart system exhaust. I am getting really bad gas mileage and i noticed some gasoline behind one of my spark plugs. Also, almost everyday, when i start my car, it will rev to like 1500 and then slowly bog down to 0 and shut off. I changed my air filter, plugs, wires and fuel filter. I think I might have a problem with my oxygen sensor, but Im not getting any check engine lights. Anyone with any helpful info, please post.....

im not sure how to test the oxygen sensor.

Thanks!!

 

[andymoraitis]

Considering how cheap an O2 sensor is, go ahead and change it out. While this is only a general rule, whitish coloring or a light tan means it's working properly, while a blackened tip will indicate that the sensor is reading lean (erroneously) and dumping fuel to compensate. It can also end up white from the lead in race fuel, but I don't think that ould apply on an N/T. The end result when it fails completely results in the ECU going into "limp" mode. No power and awful gas mileage are usually symptoms.

If you're looking for a replacement, go with an OEM unit from http://www.sparkplugs.com since they're direct fit and made to last. If it's never been replaced, now would be the time to swap it out and let us know how it goes.

Good luck!

Andy

 

[eclipse0508]

What do you mean by the ECU going into limp mode?? I am not getting any check engine codes. I do feel a power loss and Im only getting about 220miles per tank.

 

[andymoraitis]

Limp mode basically means that the ECU is running the motor in a reduced state because it perceives a condition where it needs to keep things "safe". Because failing sensors tell the ECU that everything is too lean, this is what triggers limp mode, even though the motor really isn't in any danger. So, you have a false overly lean reading and excessive fuel being dumped. Crappy gas mileage and reduced power will be the byproduct.

Note that an O2 can be in bad shape and still not trigger a code until it's really far gone. Just replace it.

 

[eclipse0508]

Hey man thanks....i really appreciate your help on this. I am going to get the Denso from sparkplugs.com....and i will let you know how it goes.

 

[DSMcrazy3]

You will need a voltmeter to perform this.​

To properly test the o2 sensor voltage disconnect the plug from the harness and check for continuity(about 12V at 68*F) between terminals 3 and 4 on the connector. If there is no continuity, replace the sensor.

Now start the engine until normal operating temp. is reached and use jumper wires to connect terminal 3 of the sensor connector to the positive battery terminal and connect a wire from terminal 4 of the sensor connector to the negative battery terminal. Now connect a voltmeter between terminals 1 and 2, now while repeatedly racing the engine measure the voltage, it should be 0.6v-1.0v. If not, replace the sensor.

*Info is straight out of the Chiltons guide.*

 

[andymoraitis]

You will need a voltmeter to perform this.​

To properly test the o2 sensor voltage disconnect the plug from the harness and check for continuity(about 12V at 68*F) between terminals 3 and 4 on the connector. If there is no continuity, replace the sensor.

Now start the engine until normal operating temp. is reached and use jumper wires to connect terminal 3 of the sensor connector to the positive battery terminal and connect a wire from terminal 4 of the sensor connector to the negative battery terminal. Now connect a voltmeter between terminals 1 and 2, now while repeatedly racing the engine measure the voltage, it should be 0.6v-1.0v. If not, replace the sensor.

*Info is straight out of the Chiltons guide.*

Leave it to Josh to have the answer on testing. Good one bro!