Understanding Air-fuel Mixtures

[xXx]

  GihanFX said:

Aiyo no machan, belive me 95 octain is better than the normal one, more gas milage, good for ur engine n sensors specially o2 sensor n u get bit more power.,,

gihan is right, 95 octane does give some protection to the O2 sensor. what exactly does the O2 sensor do? and what happens when its not working?????

[Overdrive]

  xXx said:

gihan is right, 95 octane does give some protection to the O2 sensor. what exactly does the O2 sensor do? and what happens when its not working?????

The O2 sensor is part of the emissions control system and feeds data to the ecu (computer). The whole idea of the sensor is to help the engine run as efficiently as possible and also to produce as few emissions as possible.

the efficiency of the engine totally depends of the ari and fuel mixture. This mixture has to be perfect.

a petrol engine burns petrol when in contact with oxygen (through air intake as u know) so there is a ratio for air and fuel that is just right. If there is less air than this perfect ratio, then there will be fuel left over after combustion. This is called a rich mixture. Rich mixtures are bad because the unburned fuel creates pollution. If there is more air than this perfect ratio, then there is excess oxygen. This is called a lean mixture. A lean mixture tends to produce more nitrogen-oxide pollutants, and, in some cases, it can cause poor performance and even engine damage.

The oxygen sensor is positioned in the exhaust pipe and can detect if the mixture is rich or lean. Through a chemical reaction the sensor gives out a signal to the ecu. depending on the signal the ecu detrmines if the mixture is right. then it adjusts the amount of fuel entring the combustion area. bang bang...

The reason why the engine needs the oxygen sensor is because the amount of oxygen that the engine can pull in depends on all sorts of things, such as the altitude, the temperature of the air, the temperature of the engine, the barometric pressure, the load on the engine, etc.

When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.

Hope this answers the question.

Oh forgot. Higher the octain better the combusion, thus more power, more efficient for the same amount of fuel. more power, higher the octane level...Aviasion gas. (AV GAS).

[sharkster]

  Overdrive said:

The O2 sensor is part of the emissions control system and feeds data to the ecu (computer). The whole idea of the sensor is to help the engine run as efficiently as possible and also to produce as few emissions as possible.

the efficiency of the engine totally depends of the ari and fuel mixture. This mixture has to be perfect.

a petrol engine burns petrol when in contact with oxygen (through air intake as u know) so there is a ratio for air and fuel that is just right. If there is less air than this perfect ratio, then there will be fuel left over after combustion. This is called a rich mixture. Rich mixtures are bad because the unburned fuel creates pollution. If there is more air than this perfect ratio, then there is excess oxygen. This is called a lean mixture. A lean mixture tends to produce more nitrogen-oxide pollutants, and, in some cases, it can cause poor performance and even engine damage.

The oxygen sensor is positioned in the exhaust pipe and can detect if the mixture is rich or lean. Through a chemical reaction the sensor gives out a signal to the ecu. depending on the signal the ecu detrmines if the mixture is right. then it adjusts the amount of fuel entring the combustion area. bang bang...

The reason why the engine needs the oxygen sensor is because the amount of oxygen that the engine can pull in depends on all sorts of things, such as the altitude, the temperature of the air, the temperature of the engine, the barometric pressure, the load on the engine, etc.

When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.

Hope this answers the question.

Oh forgot. Higher the octain better the combusion, thus more power, more efficient for the same amount of fuel. more power, higher the octane level...Aviasion gas. (AV GAS).

gud explanation bro...to add to dat...the oxygen sensor is attached before the catalytic converter but there may also be a second oxygen sensor attachd after the catalytic converter to check its efficiency in emission control

[GihanFX]

  Overdrive said:

The O2 sensor is part of the emissions control system and feeds data to the ecu (computer). The whole idea of the sensor is to help the engine run as efficiently as possible and also to produce as few emissions as possible.

the efficiency of the engine totally depends of the ari and fuel mixture. This mixture has to be perfect.

a petrol engine burns petrol when in contact with oxygen (through air intake as u know) so there is a ratio for air and fuel that is just right. If there is less air than this perfect ratio, then there will be fuel left over after combustion. This is called a rich mixture. Rich mixtures are bad because the unburned fuel creates pollution. If there is more air than this perfect ratio, then there is excess oxygen. This is called a lean mixture. A lean mixture tends to produce more nitrogen-oxide pollutants, and, in some cases, it can cause poor performance and even engine damage.

The oxygen sensor is positioned in the exhaust pipe and can detect if the mixture is rich or lean. Through a chemical reaction the sensor gives out a signal to the ecu. depending on the signal the ecu detrmines if the mixture is right. then it adjusts the amount of fuel entring the combustion area. bang bang...

The reason why the engine needs the oxygen sensor is because the amount of oxygen that the engine can pull in depends on all sorts of things, such as the altitude, the temperature of the air, the temperature of the engine, the barometric pressure, the load on the engine, etc.

When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.

Hope this answers the question.

Oh forgot. Higher the octain better the combusion, thus more power, more efficient for the same amount of fuel. more power, higher the octane level...Aviasion gas. (AV GAS).

kool machan thanx for the explanation, n i have a question, my vehicle rpm cutoff is at 6000 rpm. so when i shift arond 5500 - 5900 rpm, car backfires with a sound , specially in 1st to 2nd n 2nd to 3rd gears,, so o2 sensors are working properly, bt i remove the cat , is it because the rich mixture ? so wut can i do ?

n wut do u think about Octan Booster ? they say it increases octane leve 3-5 points

Thanx-

  Bhara said:

know that... just kidding machan....no worries..

Ela Ela

[Overdrive]

  GihanFX said:

kool machan thanx for the explanation, n i have a question, my vehicle rpm cutoff is at 6000 rpm. so when i shift arond 5500 - 5900 rpm, car backfires with a sound , specially in 1st to 2nd n 2nd to 3rd gears,, so o2 sensors are working properly, bt i remove the cat , is it because the rich mixture ? so wut can i do ?

n wut do u think about Octan Booster ? they say it increases octane leve 3-5 points

Thanx-

Ela Ela

How did u come to the conclusion that if the car backfires O2 sensor works properly.A car backfires because unburned fuel is getting to the muffler. (Rich mix) The heat of the exhause causes the fuel to combust, thus a backfire. Do you smell petrol from the exhaust when in idle..( Dont get ur face burnt now!!)..Y surely must be having a bigger exhaust right? Straight through?

Machan seems like u want to have the cake and eat it. Do You want a good drag car or an efficient everyday car? If were talking about max perfrmnce this is not going anywhere.

Thank the gods for not having emission control yet in SL.

The octaine boos ur talking abt is only 3-5 points, r u sure, thats not much. cos 1 octaine unit is 10 pints. A good Octaine booster will be valveline, but don't put it too often. also get valveline injctor cleaner if u have had the car for awhile. how old is ur car? No i am not promoting valveline!! I just thinkits a bloody good product.

[GihanFX]

  Overdrive said:

How did u come to the conclusion that if the car backfires O2 sensor works properly.A car backfires because unburned fuel is getting to the muffler. (Rich mix) The heat of the exhause causes the fuel to combust, thus a backfire. Do you smell petrol from the exhaust when in idle..( Dont get ur face burnt now!!)..Y surely must be having a bigger exhaust right? Straight through?

Machan seems like u want to have the cake and eat it. Do You want a good drag car or an efficient everyday car? If were talking about max perfrmnce this is not going anywhere.

Thank the gods for not having emission control yet in SL.

The octaine boos ur talking abt is only 3-5 points, r u sure, thats not much. cos 1 octaine unit is 10 pints. A good Octaine booster will be valveline, but don't put it too often. also get valveline injctor cleaner if u have had the car for awhile. how old is ur car? No i am not promoting valveline!! I just thinkits a bloody good product.

Do you smell petrol from the exhaust - YES

surely must be having a bigger exhaust right? - YES 4 inch apexi n1 muffler

Straight through? - No bt i removed the cat

so machan u think the fuel mixture is too rich so wut can i do ?

[Morgoth]

  GihanFX said:

Do you smell petrol from the exhaust - YES

surely must be having a bigger exhaust right? - YES 4 inch apexi n1 muffler

Straight through? - No bt i removed the cat

so machan u think the fuel mixture is too rich so wut can i do ?

This is an interesting topic, why not move it to "ask an expert" or something? Cos it would be helpful. I know a european car where I guess the mixture is too rich cos there is a strong smell of petrol sometimes, and the engine has stalled even at speed on occasions, is that due to flooding or what?

[Overdrive]

  GihanFX said:

Do you smell petrol from the exhaust - YES

surely must be having a bigger exhaust right? - YES 4 inch apexi n1 muffler

Straight through? - No bt i removed the cat

so machan u think the fuel mixture is too rich so wut can i do ?

angal hatharak ethida? machan it comes with the territory. when you have a bigger exhaust you burn more fuel no? As i said you have to face the consequences if you put racing exhaust.

[Overdrive]

  Morgoth said:

This is an interesting topic, why not move it to "ask an expert" or something? Cos it would be helpful. I know a european car where I guess the mixture is too rich cos there is a strong smell of petrol sometimes, and the engine has stalled even at speed on occasions, is that due to flooding or what?

whats the car, model? year?

[sharkster]

i've created this thread to continue the conversation on fuel mixtures in the post whore thread...i'll add the first bits of the convo shortly...

P.S. if u can think of a better title let me knw n i'll change it