Is My 02 Sensor Stuffeed?

[mr_rbman]

Ok guys, i recently had my car on the dyno and the tuner said my oxygen sensor isn't working, he tested it by having the car in neutral on the dyno and just holding the car at constant revs and he said it wasn't working properly.

So at the momet its currently running open loop on the power fc cause the 02 sensor is switched off , which with these currnet fuel prices is lets just say putting a nasty dent in my wallet!

Now the 02 sensor is second hand but was definitely working when the last person had it, the exact same thing was happening with my old 02 sensor which was only a year old which i got brand new which is perhaps leading me to think it could be something else?????????

On my power fc once the car is warm and is idling it reads 0.74 volts or there abouts whether or not i have the power fc set to closed loop or not.

Any ideas would be very helpful!

Should i be running the car with the 02 sensor on or off in this situation?

[mr_rbman]

anyone got any ideas?

[Busky2k]

If its sitting at 0.74V on idle, with the O2 feedback on, that means that the base tune is still probably too rich.

An easy way to see if its working is to pull out some fuel in the IGN/INJ menu by about 1% each time, and check the O2 voltage. It should start to cycle when you've leaned it out enough.

[Cubes]

Ash,

Bring it around some time and I will have another look.

I remember the 2 cells under the idle cells were set too rich that would cause it not to drop in to closed loop on idle.

Why shaun did this i'm not sure, maybe it had an idle issue when leaned out. Will find out I guess.

The position of your o2 sensor may also make it lazy as its a fair distance from the back of the turbo and is smack in the middle where the wastegate pipe joines the exhaust.

Not optimal.

On the note of fuel economy.. I've just cracked 478km's and its just above the empty line, might get another 5km's before the light comes on, the strange thing is I've driven it harder than I usually do as I've got a set of tyres on the rear that grip.

[paulr33]

02 feedback isnt the be-all and end all of economy. it cerainly is a brialliant out of the box solution for economy in self drive mode but there are alternatives

tune the car with 02 feedback off and leave it off if you wish. mine is tuned like that. 1.5 hours on the road with wideband sensor will sort out the cruise and low load AFRS to get your economy back. im seeing 400's on the street with peak hour traffic with 02 feedback off. 1.5hours tuner work should cover the cost of getting a new 02 sensor, installing it and wasting some fuel in the meantime.

[mr_rbman]

Ash,

Bring it around some time and I will have another look.

I remember the 2 cells under the idle cells were set too rich that would cause it not to drop in to closed loop on idle.

Why shaun did this i'm not sure, maybe it had an idle issue when leaned out. Will find out I guess.

The position of your o2 sensor may also make it lazy as its a fair distance from the back of the turbo and is smack in the middle where the wastegate pipe joines the exhaust.

Not optimal.

On the note of fuel economy.. I've just cracked 478km's and its just above the empty line, might get another 5km's before the light comes on, the strange thing is I've driven it harder than I usually do as I've got a set of tyres on the rear that grip.

cheers for the replies people's!

I'll be in touch with you soon joel and we'll have a fiddle with it!

I've got the car set to closed loop again now but i'm not sure if i should given that shaun obviously tuned it with it not in closed loop!

[OFENSV]

i pluged my PFC in, hasnt been tuned but i noticed one of the 02 sensors reading like 3.1volts and the other about 1.2 volts, you think they are screwed or its the pfc?

[Cubes]

Mine reads high when its not up to temp, it takes roughly 1-2km of driving for it to come up to temp and begin working.

[Busky2k]

3.1V is something wrong. They only output a max of 1V so somethings whacky. And yeah a good O2 sensor will be operational well within within 1 minute of warmup. Some take longer cos the heater is burnt out or it is not heated at all.

[Cubes]

Mines a genuine o2 sensor from nissan, it definitely reads close to 4v when stone cold then drops as it heats. Always has since I dropped it in. I forget how the old one performed.

[mr_rbman]

so should i leave the power fc in closed loop or not?

[paulr33]

you should only disable closed loop if you can tune it with a wideband sensor. i found when i turned closed loop off in some bits it was a bit too lean. as with closed loop on it leans it out and richens it up where its needed to get ideal 14.7afr. thats my experience anyway.

[mr_rbman]

cheers!