O2 Voltage Constant On Constant Rev

[Rekin]

Hello all,

After a minor tune and an extensive drag day, I noticed that my car was pulling/hesitating when crusing.

I looked into the o2 sensor voltage and saw that whilst crusing (ie constant revs) my o2 sensor voltage would sit at 0.04v and not fluctuate between 0.00 - 1v as it should. (NOTE: I am reading the o2 sensor voltage via the ECU through Consult Port Readout!)

Only when I would stop at the lights and idle it would fluctuate and when I accelerated.

So thinking it was a busted o2 sensor, I bought a brand new NTK o2 sensor.

Put it in the car and followed NTK's testing method;

Run the engine at approximately 2000 rpm. A properly functioning oxygen sensor will show a rapidly fluctuating output voltage between approximately 0.1 and 1.0 volts. The time taken for the voltage to change from 0.1 V to 1.0 V (referred to as the lean to rich response time) should be about 300 milliseconds. A similar time should be measured when the voltage changes from 1.0 V to 0.1 V (rich to lean response time).

When revving and holding at 2000rpm, the voltage is sitting constant on 0.14v and I still have the same issue of 0.04v whilst cruising on the streets. (Reading from Nissan Consult)

Therefore it appears my problem is not o2 sensor related?

My question is; What else affects the o2 sensor voltage? Why is my voltage not fluctuating? Can it be fuel-map related? (ie. my latest re-tune?)

Can I disconnect the plug from the o2 harness and directly hook up a multimeter to get a raw voltage reading? Or does it need to be plugged to the car?

Any help would be greatly appreciated!

Thanks

[Moodles2]

Is the O2 sensor, Titania-based (NTK OTx-xxx) or Zirconia-based (NTK OZx-xxx). Running rich or running lean might have killed the original sensor on the drag day (made worse by fuel additives).

Do a ECU reset, unplug the car battery and pump the brake pedal to drain whats left, and see if it still does it then.

Otherwise try to borrow a windband and check AFRs or get it back to the tuner and get them to check the AFRs.

[Rekin]

Is the O2 sensor, Titania-based (NTK OTx-xxx) or Zirconia-based (NTK OZx-xxx). Running rich or running lean might have killed the original sensor on the drag day (made worse by fuel additives).

Do a ECU reset, unplug the car battery and pump the brake pedal to drain whats left, and see if it still does it then.

Otherwise try to borrow a windband and check AFRs or get it back to the tuner and get them to check the AFRs.

Its a OZA395-E2 sensor.

Good idea about the ecu reset, ill go do that now. Will post results soon.

Thanks

[NewKleer]

get latest ecutalk v1.3.5 beta6 and log everything and post. but particularly o2, water temp, speed, aac, a/f alpha, m/r lean(whatever its called), tps.

[mad082]

i am assuming you have some form of aftermarket management (nistune, or remap, etc). if so that may be part of the issue. was it definately working properly before the drag day? and was it definately working properly after the tune? it may be that when they did the tune they partly cancelled out some of the closed loop mapping and simply tuned it to run at the desired AFR when cruising.

[Rekin]

i am assuming you have some form of aftermarket management (nistune, or remap, etc). if so that may be part of the issue. was it definately working properly before the drag day? and was it definately working properly after the tune? it may be that when they did the tune they partly cancelled out some of the closed loop mapping and simply tuned it to run at the desired AFR when cruising.

yeah I got nistune. I dont recall any problem before/after the tune, but the car was only retuned the day before the drags so cant remember if it was playing up before. I will log the sensors on the weekend and see what it reveals. Might also splice into into the o2 sensor wiring and see if its the same voltage as whats shown on the consult readout.

To be continued...

[R.3.2.G.T.R]

whats the voltage range on titania o2 sensors?

0v-1v?

mine sits at 3v+ on ignition and on startup/warm is around 1.6-18v?? does this means its dead as it doesnt really vary with revs etc

my tuner disabled o2 feedback on pfc due to abnormal readings

Edited August 7, 2010 by BWRGTR

[Moodles2]

Titania narrowband is 0v to 1v, Zirconia narrowband is 0.1v to 0.9v. I don't understand how a narrowband O2 sensor can give readings above 1v though. Can you confirm you have a PFC specifcally for a R32 GTR and are running Titania based sensors, and are both sensors reporting the same voltage, or is one showing normal range while the other is showing the wrong range (should have 2x O2 readings, the front and rear turbo)? Titania and Zirconia are electrically different too, is it possible you have aftermarket dumps and the previous owner put Zirconia O2 sensors in?

[R.3.2.G.T.R]

Titania narrowband is 0v to 1v, Zirconia narrowband is 0.1v to 0.9v. I don't understand how a narrowband O2 sensor can give readings above 1v though. Can you confirm you have a PFC specifcally for a R32 GTR and are running Titania based sensors, and are both sensors reporting the same voltage, or is one showing normal range while the other is showing the wrong range (should have 2x O2 readings, the front and rear turbo)? Titania and Zirconia are electrically different too, is it possible you have aftermarket dumps and the previous owner put Zirconia O2 sensors in?

O2 sensors are definately titania, has red wire and takes 17mm,

i have r32 gtr with 32R pfc although i have 34 gtr engine, loom wasnt touched btw

i have genuine hks split dumps and both sensors are showing 3v+ on ignition and 1.1v on warm engine

i dont know if problems is due to dead sensors or something else, as i dont want to buy new sensors only to find out it behaves the same

could it be the earth is dodgy, i have yet to test with multimeter

[Moodles2]

O2 sensors are definately titania, has red wire and takes 17mm,

i have r32 gtr with 32R pfc although i have 34 gtr engine, loom wasnt touched btw

i have genuine hks split dumps and both sensors are showing 3v+ on ignition and 1.1v on warm engine

i dont know if problems is due to dead sensors or something else, as i dont want to buy new sensors only to find out it behaves the same

could it be the earth is dodgy, i have yet to test with multimeter

Were they direct plugin O2 sensors (genuine Nissan, aftermarket etc), or did you have to re-wire the new sensors with the old plugs (possible that a heater and voltage reference wire were mixed)?

Really strange behaviour, as you should see 0v until the engine is warmed as they're heated sensors (should be seeing 0v when theyre dead)

[mad082]

it almost sounds like the pfc is reading the voltage wire and not the feedback wire. the ecu sends a voltage to a heater in the sensor to make it warm (and therefore more functional) when you first start the car and then once they heat up the voltage is dropped. almost sounds like that is what it's reading, however i thought that the voltage it sent was 12v, but then i've never really tested it.

[R.3.2.G.T.R]

Were they direct plugin O2 sensors (genuine Nissan, aftermarket etc), or did you have to re-wire the new sensors with the old plugs (possible that a heater and voltage reference wire were mixed)?

Really strange behaviour, as you should see 0v until the engine is warmed as they're heated sensors (should be seeing 0v when theyre dead)

they appear to be std o2 sensors from all the pics i have seen so far, also the wires are in the correct order on the front o2 sensor, yet to check the rear.. i will put a multimeter on both to confirm voltage readout

i will also try will voltage at pin 29 and 55 at ecu to confirm

will a dead sensor exhibit such behaviour as i always thought they just stop fluctuating once dead

[mad082]

once dead they normally stop fluctuating and will sit at a set voltage (can't remember where it is 0.1v or 1v, but it's at 1 end of their normal range)

[NewKleer]

most commonly they die at 0v or 0.3v (0.3v is also the volt it starts at often when u start car, before its heated up to temp...so make sure car was warm before assuming you have dead o2).

[R.3.2.G.T.R]

ok update time

so got out the multimeter over the weekend to do some tests, not very scientific but a stab in the dark

o2 sensor does get 12v in one the wires and the other one is 1v+ which is what shows on the hand controller and the last one being the ground.

now need to confirm, without the engine on, my voltage on H/C is 3+ volts, should it be zero????

checked at the ecu pins (29 + 55) and one is showing the 1v+ and the other oddly is showing ~0.3v which i assume is more normal

so i suspect perhaps an earth issue

paper clip into one of top plug (forget which one) to chassis for earth does reduce each of the 02 volts to below 1v (0.2 - 0.4v)

dont know if i should be earthing or just get another pair of o2 sensors..

also on a side note, if I was to put in a wideband sensor at my front pipe, will be it be able to output narrow band signal for the ecu (o2 feedback)??

[Rekin]

o2 sensor voltage should deff be between 0 - 1v. I once had a GTR o2 sensor in my GTST which would read 2.55v which is obviously wrong!

Replaced with a gtst o2 sensor and was back to 0 - 1v.

Double check the model number on the o2 sensors to confirm if you have the correct one for your car. Even though it plugs diresctly into the connector doesnt mean it is the right one.

[Rekin]

My constant o2 issue is still ongoing. Found a lot of vac hoses leaking on the manifold, along with the hose attached to the outlet of the turbo. Will replace these and see if my o2 sensor issue is fixed!

[NewKleer]

0.3v is normal voltage when car is not warmed up. so the one reading that sounds right. 12v would be heater power.

wideband can output narrowband signal (depends which you get) but i wouldnt be worrying about that till you work out the problem here.