Does running your car on LPG ruin ur O2 sensor?

[b3h3m07h]

Hi all, few weeks ago i put a new o2 sensor in my car because i kept on getting error codes 13 and 44 and i thought it work all ok. But recently ive been running my car on petrol and the 44 code is comming up again but when on LPG it never does. could it be that LPG is stuffing it up or is there possibly something else giving the wrong readings? cheers

[xcop5l]

you will always get those codes with lpg. theres no way arround them. even if it only comes on rarly. it wil still come on. it is becaise the 2 fuels have different propertys. and they burn differently so they will have different levels of oxygen coming out of the combustion chamber. so the o2 sensor will read differently.. if that made sense

[b3h3m07h]

yes but why is it coming on when using petrol and not lpg, wouldnt the ecu have a pre programed min and max for petrol but not LPG which in turn would make sense if it lit up when using LPG? possibly could the sensor be getting a lean signal from another component malfuntioning?

[Sp0tteh]

is it running rough or differently then it used to on petrol?

[JD]

not sure why it woudl put out those codes my vn clubbie never did that on gas or petrol

[crackers450]

Hi Guys
I'm new at this but I am having big problems, when running on lpg the car performs faultlessly, change over to petrol it won't idle below 1000rpm, won't run properly and gives off a strange burning smell, could it be blocked fuel line or something else ??
Laurie

[b3h3m07h]

it is running rough on both petrol and gas, im possibly thinking my valves are gone.

[Murdoch]

not sure why it woudl put out those codes my vn clubbie never did that on gas or petrol

You had a VN Clubsport and you put it on gas!!!!!
What are you doing

[vt1538]

you will always get those codes with lpg. theres no way arround them. even if it only comes on rarly. it wil still come on. it is becaise the 2 fuels have different propertys. and they burn differently so they will have different levels of oxygen coming out of the combustion chamber. so the o2 sensor will read differently.. if that made sense

Dont know if I would agree with that mate. While both fuels need a different air fuel ratio for stoichemetry. Petrol 14.7 to 1, propane 15.7 to 1 the O2 sensor measures oxygen content left after combustion. Provided that both fuels are tuned correctly the o2 sensor will read the same.

[Not_An_Abba_Fan]

I would be checking the cat, as LPG runs hotter at the manifold but cooler at the tailpipe maybe it has started to melt the front of the cat. On petrol the O2 sensor would probably be coding because of the flow being restricted and having a mixture that is too rich at the sensor. On LPG the properties of the exhaust are different so the O2 sensor wouldn't pick up anything wrong.

Just a thought....

[JD]

You had a VN Clubsport and you put it on gas!!!!!
What are you doing

no i didnt it already had it.
and that car doesn't even have the stock engine in it anymore because of it.
flyen_vn has it now and it have a VS HSV 185i motor in it, but that got the gas system on it now.
VN v8 (project/weekend car) take a look

[vt1538]

I would be checking the cat, as LPG runs hotter at the manifold but cooler at the tailpipe maybe it has started to melt the front of the cat. On petrol the O2 sensor would probably be coding because of the flow being restricted and having a mixture that is too rich at the sensor. On LPG the properties of the exhaust are different so the O2 sensor wouldn't pick up anything wrong.

Just a thought....

Code 13 no signal
Code 44 lean condition
As stated above the o2 sensor measures oxygen left after combustion not the specific chemical make up of the fuel. I would check for a loose connection in the exhaust like loose bolts at the manifold etc. This can cause an earth problem that will set the code 13 or will allow air into the exhaust stream & cause the code 44 lean condition.

[Not_An_Abba_Fan]

Didn't check what the codes actually were, was just a suggestion. No silicone based products were used on the intake side anywhere or in front of the sensor? That can contaminate the sensor and give a lean code.

[b3h3m07h]

in regards to vt1538's comment would't a leak in the exhaust system cause a code 44 on either petrol / gas operation? Also where does the oxygen sensor ground lead actually ground on the chassis?

[flyen]

no i didnt it already had it.
and that car doesn't even have the stock engine in it anymore because of it.
flyen_vn has it now and it have a VS HSV 185i motor in it, but that got the gas system on it now.
VN v8 (project/weekend car) take a look

it still has the gas system but i havent used it yet with the new engine
will get it tuned properly b4 i run it on gas

not really a fan of gas myself..on a vnv6 ****heap yeh its ok but on a vn clubsport why would someone do that..if u want better fuel economy get a v6 or 4banger but dont put a HSV v8 on gas.

[vt1538]

Yes, it should in reality read lean on both. I was just throwing another idea out there. Mind you what should happen is not necessarily what does happen.
Do you have any mods to the engine?

[walesy]

my vp 5ltr was on gas... never had any problems with it... or codes

[b3h3m07h]

ok i just thought of something. My LPG gas system a TELGAS 5000 or something actually taps into the signal line of the oxygen sensor so could this possibly when running on petrol adding a slight resistance to that line making the oxygen sensor read a low voltage thus giving error code 44? also what gas systems do u blokes have and doesnt modern cars automatically tune themselves, if not how can i do it and what equipment is required? cheers

[xcop5l]

Dont know if I would agree with that mate. While both fuels need a different air fuel ratio for stoichemetry. Petrol 14.7 to 1, propane 15.7 to 1 the O2 sensor measures oxygen content left after combustion. Provided that both fuels are tuned correctly the o2 sensor will read the same.

i agree with you about the reading part i stuffed that up... the o2 sensor will only read what is coming out of the cumbostion chamber. but you have said it your self here petrol has 14.7 parts air to 1 part fuel and lpg has 15.7 parts air to 1 part fuel there fore different amounts of oxygen going into the cylinder will have different amounts of oxygen coming out. also unburnt lpg/petrol will mix up the readings. lpg is a mixture of butane and propane and this mixture varies from servo to servo, and with the mixture changing the stoicheometric ratio for lpg will varie as the butane has a different burn property to propane. 15.7:1 is for the ideal mixture of butaine and propaine not what the servos sell you. (if i have confused any one im sorry)
also no one said that it was tuned.
i wouldent recomend trying to tune the lpg by your self. i would recomend to get the car dyno tuned on lpg it will run better. it cam be a mongrel of a job tuning lpg with the rite equipment.
also with the lpg system tapping into your o2 sensor this is so the lpg computer can make MINOR adjustments. it is better if it is set as close to perfect as posible. the computer should adjust the rest

[vt1538]

At the correct air fuel ratio both fuels will have no oxygen left in the exhaust gas. The stoichemetric ratio is how much air to fuel the engine needs for a complete burn. Any oxygen left in the gas will read lean, any fuel will read rich.
This is why the pro tuners use the EQ ratio or lamda instead of AFR. This way a vehicle can be tuned without having to know what fuel is in use.
Dont confuse the ratio going in to what comes out.

[b3h3m07h]

Cheers for all that extra information fellas but i am just looking for some reasons why the petrol system gives a lean reading and the lpg doesnt, could it be a faulty fuel pump, low pressure, stuffed injectors, really just some pointers so i can sus it all out?

[vt1538]

I think you may have had the right idea with the gas system using the o2 input. I would be checking the wiring in this area to see if there is a bad connection out of the unit to the pcm. The fact that code 13 comes up as well as 44 makes me think it is more electrical.
Bad fuel pump,blocked fuel filter,blocked injectors or air leaks are mechanical things I would check first.

[Not_An_Abba_Fan]

But he said just the code 44 comes up after he replaced the sensor.

[b3h3m07h]

yeh its just code 44 now, 13 was being set of by a bad earth connection on the O2 sensor lead.

[vt1538]

If you have a digital multimeter you can check the voltage being supplied to the pcm from the o2 sensor. Have the engine running around 1800 rpm for a couple of minutes.With the engine still running probe at the pcm with the multimeter positive on the violet lead pos D7 & the earth on the black lead D6.Does the o2 sensor read a fixed voltage below .30 volts ?
If yes disconnect the o2 sensor at the connector & note the voltage at the pcm the same way as before. Check that the voltage is now between 0.30 & 0.55 volts.
If it does then check you map sensor, fuel pressure, that your o2 sensors metal vent isnt covered with mud or a bad earth to the engine.
If not check the violet wire for a short to earth.
If you can follow these steps it should put you in an area where we can pinpoint the fault.