Hi guys, I'm trying to tune my LPG using a volt meter connected to the o2 sensor.
I'm having a hard time figuring out the conversion from volts to AFR.

At the moment I have it running at around .85v some info says that's around 14.01 other say 12.5, 13.2.

Does anyone know for sure how read this off the third gen o2 sensor?
I'm aiming for between 14 and 15.5 which appears to be the best performance/economy ratio for LPG

Apparently Petrol is stoich at .45v, so I should aim for about 300 ? or just go for 14.7 @ .45v because it won't be lean and will perform slightly better

Hi guys, I'm trying to tune my LPG using a volt meter connected to the o2 sensor.
I'm having a hard time figuring out the conversion from volts to AFR.

At the moment I have it running at around .85v some info says that's around 14.01 other say 12.5, 13.2.

Does anyone know for sure how read this off the third gen o2 sensor?
I'm aiming for between 14 and 15.5 which appears to be the best performance/economy ratio for LPG

Apparently Petrol is stoich at .45v, so I should aim for about 300 ? or just go for 14.7 @ .45v because it won't be lean and will perform slightly better

From what I've read, O2 sensors (either narrow or wide band) don't directly report AFR, but report lambda. Lambda = 1 is stoich, and in the standard Bosch narrowband configuration that is 0.45V.
Stoich for ULP is at an AFR of 14.7, for E10 stoich is at an AFR of 14.1, and for LPG stoich is at an AFR of 15.5.

So nominally you should be targeting 0.45V for LPG, as the OEM ECU does for any fuel it controls delivery of (in closed loop mode anyway). 0.85V is very rich.

If you look at the "NBSim" section of this page (http://wbo2.com/2j/default.htm), it will give you an idea of the voltage to AFR (nominally for ULP) relationship. Note that this is a simulated narrowband output from a wideband sensor, but this should be close enough, although the response of normal narrowband sensors on the rich part of the scale can vary considerably with exhaust gas temperature.

Hmm, even with the BLOS set to the minimum amount and the car nearly stalling I'm not getting any lower than around .8v, on petrol it rapidly switches around all over the place, maybe this isn't the best way to tune LPG

Hmm, ordered one of these to make things easier.

http://autospeed.com.au/cms/article.html?&A=0217

As the o2 sensor only shows rich or lean I've tuned so it's oscilating between rich and lean which I assume it stoich.