02 Sensor Check - Voltage Range And Sensitivity

[benl1981]

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 October 10, 2005 by benl1981

[Skas33]

benl1981

You can get a o2 display from jaycay for about $50 you can watch what the sensor is doing on the fly, giving you a good idea if it's working or not. Not to mention being able to watch the a/f ratio constantly

[benl1981]

Yeah - but I already have the powerfc so I can see whatit is doing. Thanks for the idea. I think the sensor is quick enough to react - at 2500 rpm its cycles quite quickly.

[justin911]

my pfc/o2 sensor reports about the same voltages.. 0.2v - 0.8v

In the r33 workshop manual It ses it should be approx 0.3v - 0.6v.. so I figured it was within spec..

[benl1981]

It also depends on the fastness of these oscillations

[RB30-POWER]

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]

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.