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02 Sensor Check - Voltage Range And Sensitivity

benl1981

By benl1981,
in General Maintenance

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benl1981 Grand Master

benl1981

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My fuel economy on the highway is still at about 11L/100km for an R33 gtst with very smooth and small throttle openings - i.e not good for a 2.L 6 cylinder (A 3.8 commo can do better)

I have hooked up a Powerfc and you can do a sensor check - at idle the 02 sensor varies between 0.1v and 0.9 v like it should :)

However, it seems to stay on say for example 0.85v for about 1 second or so then drop to the 0.1v or thereabouts. I was reading on the web and found that it should be about 300ms for a healthy sensor...

Anybody that has put a new one in noticed a change in reaction time and fuel economy?

Sorry the other thread is getting huge. This thread may help people to determine if it is worth replacing as I read a lot of people replacing with no change :)

Minimum and maximum sensor voltages are just part of the picture. How fast these transitions occur is an equally important measure of O2 sensor health. Lean-to-rich and rich-to-lean transitions should occur in 300mS or less; anything greater may indicate a worn or contaminated sensor. An oscilloscope or graphing multimeter is essential for this test.

Seems like because ours are heated they generally have a longer life...

Heated oxygen sensors have smaller slots in the protective tube at the tip. This limits the amount of exhaust that reaches the sensing tube, and limits the contaminants that can reach the sensor and diminish its response. Consequently a heated O2 sensor may last 100,000 miles or more.

o2 sensor info

Edited by benl1981
RB30-POWER Mentor

RB30-POWER

Posted
Posted

Drive along at light load at 2500rpm or so, and it should crosscount back and forth quite rapidly.

At idle, if the sensor is a bit old, it will be quite un-responsive and make it difficult to determine what happening.

So yeah, check it as your drive along, that way there is alot more hot gas flowing past the sensor and the response should be quite rapid!

On a standard ecu and mild car, it should be in closed loop right up to 0 vacuum on the boost guage.

benl1981 Grand Master

benl1981

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Thanks RB - yeah at 2500rpm it was fairly quick at oscillating back and forth.

I guess I'll see on the dyno if it is actually holding 14.7 AFR though.

Hey RB acan you check my last post in the thread Crap fuel economy (in Gerneral Maintenance area)..thought you may know.

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