Oxygen sensor and gas

[levymetal]

Hey guys, I was just wondering if the oxygen sensor has any effect on the mixtures for lpg at all. Ever since I got gas installed, I've been having the check engine light pop up, so I checked the codes and it comes back as 44 - Oxygen Sensor Lean (O2). As far as I know, the computer then richens the mixture up to compensate. I was thinking that it just reads different because of the gas, and that it doesn't matter because I don't think the computer controls the mixture for gas. But then the check engine light comes on when using petrol as well (I should really check to see if it's the same code, but I assume it is). It only comes on for a bit, then goes away. Could this be affecting my economy, even on gas?

[Blown V6 Hatch]

The 02 sensor is the only way the LPG computer can tell what the mixture is, so yes in short, the 02 sensor is a big part of the gas system. Having said that, most gas powered cars have the engine check light come on from time to time and 99% of the time it will be an 02 sensor related code. Replacing the 02 sensor will fix the problem for a short period, but it will end up with the check light coming on again, but the 02 sensor needs to be replaced about every 40,000 k's on gas, so replace it and go from there. The engine light coming on when on gas is nothing to get too concerned about, it's just one of those things with owning a gas powered car.

Anyway, thats just my findings from working on gas powered cars, but i'm sure one of the gas "experts" on here will say different.

[DavoVP]

mines on gas and i have the same thing, did it since i braught it when it wouldnt run on gas at all.

[Vt-Brrrlina]

nope my old vp the same - replace it regularly unfortunately - once of those added bonus's of cheap fuel - O2 sensors burn out that bit quicker - once its renewed u prob shouldnt see that code for some time again

[levymetal]

i guess mine probably is buggered now that it's showing up when the car's on petrol as well as gas! are the ones off egay any good? or should i just go to repco...

thanks for your help guys!

[Not_An_Abba_Fan]

Is it an LPG carby or injected set up? If it is carby, how does the ECU adjust the mixture? It is a screw on the side of the mixer that does it.

My missus VN is LPG carby, no petrol at all, fuel tank has been removed, injectors are all unplugged. The ECU has nothing to do with the fuel mix on her car. Doing a code check brings up the O2 sensor error but it does nothing in her car anyway.

[Cheap6]

A gas conversion on a car using closed loop fuel control - simplistically running on unleaded fuel and using a catalytic converter - and converted after 1989, will use the O2 sensor for fuel mixture control when running on LPG, as well as on petrol. The LPG mixture (on all but SVI/LPI LPG) will be controlled with an electronic unit external the factory ECM though.

The reason O2 sensor code(s) set(s) on LPG is that the rate at which the fuel mixture, and hence the O2 sensor voltage (signal), varies on LPG is necessarily much slower with an LPG carb. set up than with the petrol injection system. The response is outside the range of normal O2 sensor operation so codes can be set.

If the mixtures on LPG are different from that on petrol (on average they should be the same - different is an LPG tune issue) the ECM will attempt to correct for the error, despite having no control over the fuelling, and learn new values for the petrol injector opening times (fuel map). When you revert back to petrol operation after driving for some time on LPG, O2 sensor codes can also set on petrol until the ECM again learns the correct values for petrol operation. To be certain that this is happening, clear the ECM memory and drive on petrol - no O2 sensor codes should be found.

The factory LPG system includes a Memcal that will not set the O2 sensor codes, nor relearn the petrol fuel map, while operating on LPG.

[Circlotron]

...running on unleaded fuel and using a catalytic converter - and converted after 1989, will use the O2 sensor for fuel mixture control when running on LPG, as well as on petrol.

That's interesting.
My VP was converted in 1993. It is a Gas Research setup and doesn't appear to have and kind of mixture controlling device. What's more, the O2Low and O2Hi malfunction detect bizzos in the memcal are turned off. Sounds like a bit of corner cutting to me.

[mr calais 5.0]

My v8 vn is on duel fuel and I mainly run gas and never get the light come on.. Are you guys running stock spark plugs and gas motor oil?

[Circlotron]

Dunno about the plugs. I'm running ordinary old GTX or something, not gas oil.

[drewVHSS]

my mates' vr wagon does it as the ecu thinks there's an issue with the petrol whilst in lpg mode, with his old vq statesman i did the wiring (identical system) and found two extra wires to connect to the ecu that on his vr wasn't connected, it had something to do with telling the ecu that it's ok that the injectors aren't firing (due to the intercept on the injectors from the lpg system) whilst the fuel pump was still pumping fuel.

I'll take a wild guess the engine light usually lights up when you're stationary for a little while at lights etc but goes away when you're moving again?