O2 Sensor Voltage SR20DET

wombat · Post by **wombat** » Sun Jan 27, 2008 3:17 pm

Hi all,

Does anyone happen to have a conversion table, or at least know the voltage to AFR equivalents for the 1.5V O2 sensor in the SR20DET? Specifically, the GTi-R. The voltages appear to be completely different to usual zirconia sensors.

Cheers.
-Adam

Fusion Ed · Post by **Fusion Ed** » Sun Jan 27, 2008 9:04 pm

They are, but you cannot use it to find AFR values they are too narrowband. Just get a real wideband if you want to know AFR.

wombat · Post by **wombat** » Mon Jan 28, 2008 12:25 am

Cool, yes, a wideband would be great, but I'd like to know where the stoich point is. Also, it'd be nice to know if I am still running at 10:1, or if my fuel restriction mod did the trick. No tuning, just a rough guide. I'm sitting at 1.4v at the moment under WOT and also at idle.

Can anyone give me a rough idea?

Cheers.

Eric · Post by **Eric** » Mon Jan 28, 2008 5:50 am

As far as I know. the GTI-r uses Titanium/Titania O2 sensors.

Apparently they work completely different as the more common zirconia sensors, but from what I've seen on my own GTI-r is that the ECU assumes stoich as roughly between 1/3 and 2/3 of the full voltage range.
So for these sensors it looks like it's roughly between 0.5 and 1.0 Volt.

anything lower then 0.5V is lean, everything above 1.0 volt is rich

-Eric

Fusion Ed · Post by **Fusion Ed** » Mon Jan 28, 2008 9:56 am

I would agree with the above.

Also, it'd be nice to know if I am still running at 10:1, or if my fuel restriction mod did the trick

Why on earth did you need to do a fuel restriction? Everything about the fuel system (except pump and injectors) is fine for 450+ bhp. There should be no need to do anything like that!

wombat · Post by **wombat** » Mon Jan 28, 2008 11:54 am

Lol, settle pettel

I had a blocked fuel return which was causing 90psi base pressure and richer than or equal to 10:1 afrs. I found the return blockage and fixed it, and my pressure returned to the normal range. My R still runs rich though, so I need to get to the bottom of it. I didn't block my return on purpose lol.

Yes, the GTi-Rs run on the Titania sensors which are resistance producing instead of voltage producing. ie, you need to pump voltage into it, and read the returned result, rather than the sensor itself producing any voltage.

My mate's GTi-R idles at 1.1v, and mine idles at 1.4v. I'm thinking of adjusting the kconst to bring it down to 1.2v and see how that goes, but I am a little hesitant, as I don't know if 1.1v is too rich or lean.

Has anyone got a wideband who can test it out? Matt - do you have one? All I need is for someone with a wideband to idle the car at 14.7:1 and tell me the voltage reading on Nistune for the standard O2 sensor. Plus, other afrs would be useful, but I won't hold my breath lol.

Cheers.

RB30-POWER · Post by **RB30-POWER** » Mon Jan 28, 2008 7:22 pm

if you can't afford a $300 techedge wideband to check mixtures, you can't afford a rebuild, why risk it?

wombat · Post by **wombat** » Mon Jan 28, 2008 7:59 pm

I've got dyno time booked already for mid next month. All I need to know is a ballpark figure so I can tell if I'm running stupidly into the black. If you don't know, no worries. Feel free to donate a wideband to me mate

Bernardd · Post by **Bernardd** » Tue Jan 29, 2008 12:37 am

check your sparkplugs

Fusion Ed · Post by **Fusion Ed** » Thu Jan 31, 2008 8:17 am

The stock ECU does a GREAT job of getting the lambda right in closed loop, provided the O2 sensor is working as it should be. Its really simple, hold idle at 2000 rpm watch the alpha learn feedback. It should be around 100%. If it its then its fine and the fuel table will be pretty accurate.

I've lost count of how many RNN14's I have worked on now, and I can tell you the above is accurate