What's oxygen sensor?

An oxygen (O2) sensor does what its name suggests - it senses the presence of oxygen in the exhaust and sends varying voltage to the electronic control unit (ECU, computer, etc), depending on the amount of oxygen in the exhaust. The higher the oxygen content, the lower the voltage. By monitoring the amount of oxygen in the exhaust, the ECU will adjust the ratio of fuel to air.

A Toyota Camry will have anywhere from 1 to 4 O2 sensors, depending on the year and engine. A modern Camry with a 4 cylinder engine will have 2 O2 sensors and one with a 6 cylinder engine will have 4 O2 sensors.

Do you happen to know if a car is converted to use natural gas, will some or most pollution control devices not be necessary? Just curious.

mark_

I dont know about legally, but generally most gas conversions utilise all the stock sensor equipment to provide best control over the engine

- all it does is work on a different AFR.

J

Theoretically, the product of perfect combustion is CO2 and H2O. Although natural gas burns cleaner than gasoline or diesel, it still is not 100% efficient so I'd say that most of the pollution control devices are still necessary. Also, natural gas does not have the lubrication properties that gasoline and diesel have.

The use of gaseous fuels (natural gas, propane, hydrogen) presents an additional set of problems over the use of liquid fuels.

In order to carry a useable amount of gaseous fuels, it must be compressed so special pumps and compressors (which require more power to operate than liquid pumps) are needed in the distribution supply chain.

Storage and transportation of compressed gasses requires a much sturdier and heavier vessel/tank, which cost more to make, require more materials to make, and which require more energy to transport - it takes more fuel to move a 200 pound fuel vessel than a 60 pound fuel vessel.

The shape of a compressed gas vessel will be a globe, cylinder, or box, making it more difficult to design into a passenger vehicle or reducing or eliminating cargo space.

A leak from a compressed gas vessel is much more difficult to control and of course, the resulting gas cloud can explode.

Every connection in a gaseous fuel supply chain, from where it comes out of the earth to storage, transportation, storage at the fueling stations, storage in the vehicle using the fuel, and movement from the vehicle tank to the engine must have a much higher resistance to leaks.

There is no delivery and fueling infrastructure for widespread use of gaseous fuels. Gas stations would have to be converted for storage of propane or hydrogen. Natural gas, as it is delivered to buildings in the U.S., is not under high enough pressure to be able to store in a usable quantity in a car so the consumer must acquire a natural gas compressor and be able to operate it safely. Think about the lowest common denominator among the drivers you see on the road and whether you would trust them to operate a system that handles explosive fuel and drive a vehicle carrying that explosive fuel on the road right next to you.

It is much more difficult to make a compressed gas vessel as crashworthy as the current generation of liquid fuel tanks.

Even if hydrogen fuel cell vehicles could be produced at an affordable cost, all those challenges to store, distribute, and transport gaseous fuels will have to be overcome.

Just as a side comment LPG is now very common in the UK, there is sufficient infrastructure installed to mean you are never really in a place where there isnt a supply unless you are in the highlands of Scotland and the hardware is very well proven. AFAIK there has only been one case of explosion due to leak from an LPG tank and that was due to the person leaving the tank connected in the boot but not held in place - it rattled too and fro until the pipes fatigued. The whole process is now legislated around and certified, insurance companies have to be informed and certificates presented.

We run a 3.5ltr bmw on gas, and have run a V8 rangerover on gas, both successfully only paying 38p per litre, as opposed to the current 101p per litre for unleaded!

LPG is used in a lot of other industries and applications and the vehicle fuelling side has only really added to what was there - we, like others, get ours from a chemical supply company down the road who supply all sorts of gasses. They now just get more delivered to cope with the demand.

A guy near me runs a 1.1 litre fiat on gas and gets 600 miles to =A313 of LPG!

Just as a side comment LPG is now very common in the UK, there is sufficient infrastructure installed to mean you are never really in a place where there isnt a supply unless you are in the highlands of Scotland and the hardware is very well proven. AFAIK there has only been one case of explosion due to leak from an LPG tank and that was due to the person leaving the tank connected in the boot but not held in place - it rattled too and fro until the pipes fatigued. The whole process is now legislated around and certified, insurance companies have to be informed and certificates presented.

We run a 3.5ltr bmw on gas, and have run a V8 rangerover on gas, both successfully only paying 38p per litre, as opposed to the current 101p per litre for unleaded!

LPG is used in a lot of other industries and applications and the vehicle fuelling side has only really added to what was there - we, like others, get ours from a chemical supply company down the road who supply all sorts of gasses. They now just get more delivered to cope with the demand.

A guy near me runs a 1.1 litre fiat on gas and gets 600 miles to £13 of LPG!

********* Interesting information. How big is the LPG tank in the boot? Does the tank make a big difference in useable cargo space?

LPG is widely used in the U.S. to power industrial lift trucks. Rather than refilling the tanks, the tanks are just exchanged. The tanks used to power industrial equipment here is a lot larger than a lot of people are able to lift, especially elderly folk.

Also, the government here would want to figure out a way to get taxes from propane tanks.

Yes, naturally its a 70 litre tank (about 250 miles range) and its approximately 800mm long and 450 diameter. IT sits between the rear struts and prevents the fold-down seats being used to add to cargo space but the car isnt used for that (we have a landcruiser for big stuff). But it still allows us to pack the boot with outboard motors and holiday stuff - the 5 series boot is fairly big.

I see your point. The place where we fill up are the sort of place that refils/exchanges those tanks. And garage forecourts which have increasingly added LPG to their list of fuels right next to the petrol and diesel pumps.

Ours put a tax 'freeze' on LPG - its not been upped for a long long time in a bid to reduce emissions. I believe you can even get road-tax reductions if your car is LPG only due to the low carbon emissions, but dont hold me to that!

J

I think the tank you are describing is approximately the same size as those used for forklifts in the U.S. The ability to refill the tank would be nice here in the U.S. but fire and zoning codes prevent most places from having the bulk tank to refill from. The industrial users have the tanks delivered, and the tank must be stored in a wire cage outside the building. Consumer propane tanks like those used for barbeque grills are much smaller and most places just exhange tanks instead of refilling them.

LOL! If LPG were to come into widespread consumer use for autos here in the U.S., I am not so confident that politicians here could resist the urge to tax it.