Just a question. Does anyone here run no Oxygen Sensor?

From reading, it seems our cars can run fine without one, they just go into open loop, and all fueling is calculated from preset maps on the ecu. Sounds better to me this way.

yeh i do, and i have done so for the last seven months and had no problems. never has had an emission problem and cops never said anything.

mike

given recent threads relating the O2 sensor to fuel consumption i would like to know about this too.

but my gut says that its there for a reason, prob best to keep it

Oh and my average per 100kms is about 10-11ltrs

I assume, that with running no O2 sensor, you may need a retune to get the best out of the car.

But seeing that the aim of the o2 sensor is to send info back to the ecu, inorder to achieve a air-fuel ratio of 14.7:1. This ratio produces the least exhaust emmisions apparantly, but, we all know, a 14.7:1 afr ratio is not what we want inorder to gain power.

Yeh i got the car retune once i disconnected the O2 sensor. reason being it is burnt out anyways lol when my car was running really rich beggining of the year, because of air leaks, hoses on wrong etc... it burnt the poor sensor out, and i got it disconnected because at the time i couldnt fix it due to no money.

Oh and my average per 100kms is about 10-11ltrs

heh i get that economy with my blower :nuts:

heh i get that economy with my blower :nuts:

Is that downhill in neutral? :P

Is that downhill in neutral? :P
nah, its what the tow truck gets

nah, its what the tow truck gets

lol

no i seriously get 9.8-10.2 per 100, i did from tamworth to Newcastle to Taree several weeks ago was about 480k from memory and i used 47.6l of fuel, as i have the reciept in my wallet

without an 02 sensor the car can only be tuned for one state, either open throttle or light throttle.

You will lose out the gains from one if you pick and tune for the other.

i would be apprehensive about it but on the other hand, on low throttle applications i have tuned my SAFC so that there is no more trim left in the fuel map (equivlant to having no 02 sensor feedback). This is irrelevant when i stomp on it as i have left the 40% throttle or more fuel table standard.

Not really oxy sensor related, but my Beast does 8/100 with 120 plus kg in the trunk, 2 ppl, and hard driving, on holiday long trips. That's a bit of difference. up to 12/100 in Sydney suburb driving tho.


lol
no i seriously get 9.8-10.2 per 100, i did from tamworth to Newcastle to Taree several weeks ago was about 480k from memory and i used 47.6l of fuel, as i have the reciept in my wallet

Not really oxy sensor related, but my Beast does 8/100 with 120 plus kg in the trunk, 2 ppl, and hard driving, on holiday long trips. That's a bit of difference. up to 12/100 in Sydney suburb driving tho.

depends, the o2 sensor can affect your economy greatly if its burnt out, if its not giving readings and the ecu goes into the closed loop its not uncommon to see 13-16l per 100, given that i have a chunk of blower sitting on top of my motor 10l per 100 is not bad, pre blower i was getting 7-8l per 100 on the highway.

I assume, that with running no O2 sensor, you may need a retune to get the best out of the car.

But seeing that the aim of the o2 sensor is to send info back to the ecu, inorder to achieve a air-fuel ratio of 14.7:1. This ratio produces the least exhaust emmisions apparantly, but, we all know, a 14.7:1 afr ratio is not what we want inorder to gain power.

isnt 14.7:1 the stoicometric ratio? (IE the ideal ratio), this is where cars run getting the maximum power and minimal emmissions, but cars on a standard factory tune will run slightly leaner, towards 14.1:1 ratio as this gives better fuel economy without sacraficing too much on performance or emissions? some one correct me if im wrong??????

Generally cars run in closed loop using the O2 sensor to maintain close to lean ratios. Part to full throttle results in the car going into open loop without the O2 sensor being used.

The stoichiometric ratio 14.7:1 means you need 14.7 units of mass of air to 1 unit of mass of fuel for complete combustion. Lower and its too rich, with the O2 sensor seeing theres too much unburnt fuel in the exhaust, and higher its too lean with excess oxygen in the exhaust. Having the O2 sensor giving feedback to the ECU is primarily to reduce emissions and increase efficiency, not so much performance.....however it is not a performance hindering device.

Snap the throttle though and the ECU goes to the fuel map to determine how much fuel to give the engine given various parameters. Everything errs on the side of too rich as it heaps the engine keep cool and on those hot days keeps detonation at bay.

Generally cars run in closed loop using the O2 sensor to maintain close to lean ratios. Part to full throttle results in the car going into open loop without the O2 sensor being used.

The stoichiometric ratio 14.7:1 means you need 14.7 units of mass of air to 1 unit of mass of fuel for complete combustion. Lower and its too rich, with the O2 sensor seeing theres too much unburnt fuel in the exhaust, and higher its too lean with excess oxygen in the exhaust. Having the O2 sensor giving feedback to the ECU is primarily to reduce emissions and increase efficiency, not so much performance.....however it is not a performance hindering device.

Snap the throttle though and the ECU goes to the fuel map to determine how much fuel to give the engine given various parameters. Everything errs on the side of too rich as it heaps the engine keep cool and on those hot days keeps detonation at bay.

what he said

cars rarely push 14.7:1 though as any leaner is classed as a detonation event, which is not good on hi-compression cars like ours. Newer lowish compression 8.0:1 cars actually run in closed loop a.f.r's close to 15:1 with very little igniton advance, at cruising speeds above 70 on under 10percent throttle to make the most of fuel, our magnas didnt have this kind of technology, but could be tuned in if you went stand alone engine managment

About a year ago my O2 sensor was stuffed. Before I replaced it, I noticed I was getting about 1-1.5L worse than normal fuel economy in daily driving, but no other differences.

Yes, in a nutshell a working O2 sensor allows the ECU to run in closed loop mode during lean-cruise and low-throttle situations. Without a functioning O2 sensor, the ECU will use pre-determined maps, which are rich to allow for a margin of error.

My tune is 12:1@WOT across the board, however in lean cruise/low throttle/idle situations I saw it get as lean as 18:1 on the dyno - although I suspect at this point it is actually in open loop, as I believe narrow-band O2 sensors can't measure AFRs so far from the 14.7:1 stoich.

Anyone know what the range of a narrow band O2 sensor is? From memory it's something like 12.5:1-15.5:1.

O2 sensors tend to misread or react slow as contaminents from the exhaust build up on it's surface. Apparently often an O2 sensor can be "fixed" by simple cleaning it with a quick blast of a blowtorch. But then again, for a relatively low cost I'd just replaced it for peace of mind. If your car is running abnormally rich for some reason, the O2 sensor will become stuffed nice and quick.

My O2 sensor was stuffed by around 85,000kms, so the service life for them doesn't seem to be that great.

sweet thanx guys, sorry for hijacking the thread too