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O2 Sensor Voltage @ X Rpm, What Should It Be?

NateR31

By NateR31,
in Engines & Forced Induction

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NateR31 Grand Master

NateR31

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Recently my o2 sensor died, so i replaced it with a ford el item, works fine again, but what should the voltage be @ x rpm? when i nail it it vairys from .80 - .90v's and while cruising i thkn closed loop mode is .04v but im not sure, can somone with a pfc check thier voltage for me? at first start up, and while cruising when it goes in closed loop mode, also when giving it a thrash?

thanks

paulr33 Grand Master

paulr33

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it has nothing to do with rpm. its based on cruise load

when cruising (constant throttle below 4000rpm) it should bounce slowly and then become steady. you can use SENSOR SW CHECK to see its value

NateR31 Grand Master

NateR31

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it has nothing to do with rpm. its based on cruise load

when cruising (constant throttle below 4000rpm) it should bounce slowly and then become steady. you can use SENSOR SW CHECK to see its value

thats what ive been looking at, tomorrow morning ill write down all the values from cold to warm and cruising when i get to work, because i still think its using a bit too much fuel.

When i first fixed it, 450kms easy out of a tank. now its around 350 ish :P

paulr33 Grand Master

paulr33

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its all relative on how you drive the car.

my car has been leaned out off the planet with a wideband sensor and sure as hell if i give it consistent curry on the streets i can get around 330's on a full tank. if i baby it around i can get 400k's to a full tank.

how are you driving it? i would expect 250ks to a full tank regardless of load / driving habits with a busted 02 sensor, incorrect voltage, or 02 feedback off.

blind_elk Grand Master

blind_elk

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At cruise (constant load), it will continually cycle between a low value and a high, but overall should average out at 0.5V. This is the software in the ECU continually adjusting the fuel to achieve a stoichiometric A/F mixture. It cycles becuse it is reactive, and is so stupid that it can never actually learn what the correct value is.

Under load (boost), it will read high, becaue the ECU is programmed to enrich the fuel component of the Air / Fuel mixture.

When you back off (snap throttle shut, either in gear change, or sudden deceleration), it willl go to 0V (ultra lean) because the ECU has shut down the injectors for a short time.

NateR31 Grand Master

NateR31

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alright today..

started the car at 6am and it was on 0.88v , drove around and it droped to 0.06v while cruising, bouncing up and down a bit from .06v - .12v, but always setteling on 0.6v. when in giving it some gas the max volt it sees is 0.90v.

befor it goes into closed loop mode and bouces ont he lower volts is up around .60v-.80v.

NateR31 Grand Master

NateR31

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Funnily enough, the output of an oxygen sensor has jack shit to do with RPM. Its output depends on the oxygen content of the exhaust gasses (which is why its called an OXYGEN sensor, not an RPM sensor)

i know this now from pauls post..

but the way i thought of helping my problem was, there would be more ext gasses at 6000rpm than at 1000rpm, hence giving it a different reading..

anyway

rob82 Mentor

rob82

Posted
Posted
Funnily enough, the output of an oxygen sensor has jack shit to do with RPM. Its output depends on the oxygen content of the exhaust gasses (which is why its called an OXYGEN sensor, not an RPM sensor)

It does if your testing its oscillation as over 4000rpm your open loop.

Cubes Grand Master

Cubes

Posted
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thats what ive been looking at, tomorrow morning ill write down all the values from cold to warm and cruising when i get to work, because i still think its using a bit too much fuel.

When i first fixed it, 450kms easy out of a tank. now its around 350 ish :P

Have you noticed any drivability issues with extremely light throttle? stumbling when you give it a quick stab from idle? hard lumpy cold starts?

My fuel consumption was fine one day then basically sh*t the next. Replaced o2 sensor, no difference, replaced injectors with instant improvement/back to normal economy.

Strange enough around 350km's per tank is what mine dropped to when the injectors decided no more.

I've always wondered if running them at 100% duty accelerated their death.

In closed loop mode the o2 sensor flicks between 0.2v and 0.8v. It should flick back and forth around 3 times within 1 second (from memory) with rpm above 2000rpm. If you find the voltage settling for any period of time it means its NOT in closed loop, i.e when you are giving it a little it will generally sit anywhere between 0.72v and 0.94v depending how rich its running. Mine hangs around 0.86v at WOT.

When mines first started obviously the o2 sensor is not operational as its not up to temp, I remember seeing 3.94 or something volts, it gets up to temp fairly quickly once driving and beings flicking between the 0.2 and .8v.

NateR31 Grand Master

NateR31

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Have you noticed any drivability issues with extremely light throttle? stumbling when you give it a quick stab from idle? hard lumpy cold starts?

My fuel consumption was fine one day then basically sh*t the next. Replaced o2 sensor, no difference, replaced injectors with instant improvement/back to normal economy.

Strange enough around 350km's per tank is what mine dropped to when the injectors decided no more.

I've always wondered if running them at 100% duty accelerated their death.

In closed loop mode the o2 sensor flicks between 0.2v and 0.8v. It should flick back and forth around 3 times within 1 second (from memory) with rpm above 2000rpm. If you find the voltage settling for any period of time it means its NOT in closed loop, i.e when you are giving it a little it will generally sit anywhere between 0.72v and 0.94v depending how rich its running. Mine hangs around 0.86v at WOT.

When mines first started obviously the o2 sensor is not operational as its not up to temp, I remember seeing 3.94 or something volts, it gets up to temp fairly quickly once driving and beings flicking between the 0.2 and .8v.

the car is driving fine, have no cold start issues except for the odd hunting now and then. Injectors are only running at around %8x.

Maybe ill run some injector cleaner through the system and see how it goes

thanks

blind_elk Grand Master

blind_elk

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Perfectly normal

started the car at 6am and it was on 0.88v ,
The engine is cold, the O2 sensor probe is cold, the ECU adds fuel (mixture rich).
drove around and it droped to 0.06v while cruising, bouncing up and down a bit from .06v - .12v, but always setteling on 0.6v.
Engine is now warm, O2 sensor probe is hot, ECU running 'normal' mixture.
when in giving it some gas the max volt it sees is 0.90v.
ECU enrichens mixture under high loads.
NateR31 Grand Master

NateR31

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thanks for that! So according to everything its working fine..

But why am i molesting fuel :D

I dont even make boost when i drive to and from work :rofl:

Do you think using some injector cleaning stuff would work, is there a better way to clean them other than running the stuff though the system?

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