SR20DET B-Top O2 Sensor.

[drkidd22]

Hello all,

I have a quick question. How can I find out if my stock O2 sensor is working properly??

The reason I ask is because I have a PLX devices AFR wideband and it's always reading about 15.5-16.3 (lean) during iddle. I unplugged the stock O2 sensor and the engine ran the same way, nothing changed at all. I don't know if the stock O2 is bad and the ECU is always trying to keep the mixture at the levels my wideband is reading.

Also I installed a Nismo FPR and Walbro fuel pump, but I have not regulated the fuel PSI, in fact I don't even know my fuel PSI which it could be a factor in there. I'm just trying to figure out about the O2 and what it is that it really does.

[Projectenzo]

google it!

[drkidd22]

i've done that...no luck...that's why i posted the question

[GSXRJJordan]

Fuel pressure is definitely a concern - why would you install an adjustable FPR with no gauge? How were you planning on adjusting it lol?

Lean at idle is OK... lean during cruise is OK... lean during acceleration (especially in the boost) is NOT OK. What's your wideband tell ya during a 2nd gear pull?

[drkidd22]

Yeah, I tihnk it was a little stupid of me to even put in the FPR w/o making sure it was adjusted to the required PSI in the first place.

But why would the car run the same way with the stock o2 sensor unplugged?

[jdms13.4]

I've had my stock o2 unplugged since day one. get a gauge for your frp and adjust the press.

[drkidd22]

I've had my stock o2 unplugged since day one. get a gauge for your frp and adjust the press.

Ok...so what is the difference? there should be something going on then. It's there for a reason, it sends data to the ECU for processing and the ECU uses it for something else. what is the need ofr it then?

[drkidd22]

ok so I set the fuel at the FPR to 42 PSI and the wideband still at 15.8-16.2 during iddle with and without the stock o2 plugged it.

[godsmack]

There should be a difference when you unplug the 02.

[fliprayzin240sx]

What do you have for your tuning? Are you running a stock ECU, maybe a PFC? If your running a standalone like a PFC, you have the option not to use the stock o2 sensor. On my PFC, without the o2 sensor on, my AFR is roughly 11.5-12.0 afr on idle. But once i turned the sensor on, it bumped up to 14.0 or so.

[drkidd22]

There should be a difference when you unplug the 02.

There is no difference, I've done this already a few times and there is no change in the engine. I think it only matters in the later engines, S14,S15. on the S13 the heater will always be turned on where as the s14 ecu turns the o2 heater on and off depending on engine load/RPM. I got it figured out I think. It doesn't really matter if the o2 sensor is plugged in on the S13 as long as the timing and the fuel pressure are right also considering that the right MAF sensor is being used and mapped correctly. The fuel pressure might need to be adjusted between seasons(winter/summer) because of the change in the air density. That's my theory. I will have my O2 plugged in anyways and test with and without it to see if I can come up with some more data.

[drkidd22]

The problem was the fuel pressure. AFR is now 14.9 iddle