HELP! Definitive answer on o2 cal at altitude?

[smurfinator]

This is really screwing me up!

I calibrated my sensor at exactly sea level. 

Then I moved to Denver - 5280 feet.

After a month or two I checked my sensor calibration with Terminal and it said 17%.

So, I fiddled with the numbers until it said 20.9% again but NOW (a year later) I just read that once the sensor is used, you can't calibrate it.

What do I do?  Should the sensor read 20.9% at 5000ft or 17%?

Should I put it back to 17% even though it's used because that's what it said after being properly calibrated at sea level when new?

What....the....forceful copulation!?!?!?!?!?!?!

Thanks for any info.  No speculation, please.  I need a scientific answer so my head does not explode.

[rob@vems.co.uk]

Once the sensor has soot on it it will never read O2 again properly, unless you can burn all of the soot off, and blow it out with compressed air (potentially damaging the sensor in the process).

The calibration is used for extreme values, i.e. it will always read lambda 1.0 at lambda 1.0 but once you move away from 1.0 the error come into play, the further you move the greater the error.

I would, in the first case get a new sensor and calibrate it fresh.

Failing that I'd go back to the original calibration value that you used.

[PeepPaadam]

What about removing the sensor? Does it alter VE table in some direction when using 1.0.73 firmware that seems to use Lambda target tables even when VEMS is set to operate on open loop (EGO correction disabled)?

[gunni]

That lambda table is there for you to have a more correct VE map.

the Lambda map is a correction/compensation map.

If you unhook the WBO2 sensor nothing fuel wise will change except if it tries to run closed loop

[GintsK]

I suppose BOSCH sensor is self-adaptive device to altitude. If You look closer to connector you will find breathing filter. Sensor element is connected to atmosphere through wire (like hose) and mentioned filter. So reference O2 will be less on high => readings stays correct

[PeepPaadam]

That lambda table is there for you to have a more correct VE map.

the Lambda map is a correction/compensation map.

If you unhook the WBO2 sensor nothing fuel wise will change except if it tries to run closed loop

Yes, I know the purpose of the VE and Lambda tables, but disabling EGO correction (but leaving sensor in place to get reading) and then changing Lambda table changes AFR readings when using 1.0.73. Why?

[lugnuts]

<<< changing Lambda table changes AFR readings when using 1.0.73. Why? >>>

- This is a feature. Autronic and other ECU do this.

- Ideally, you tune the engine to the values in the Lambda Table. Then, if you would like to run different Lambda values later on, you simply type in the new values (instead of having to re-tune the Fuel VE table)

[GintsK]

I am happy with this feature!!! With it VE table is more informative - it is clean from distortion from e.g. "cruising valley" . Easy to change desired/commanded AFR even without driving a single meter. Also you can tune VE table with conservative AFR. And then find ideal on dyno changing Lamda table only!

[cliffb75]

If you unhook the WBO2 sensor nothing fuel wise will change except if it tries to run closed loop

This is only true if you run a MAF or MAP based system.

If you are using TPS as the load input, the reduced air pressure at altitude will not be compensated for.

Fortunately the effect is to deliver more fuel than is needed as you go up in altitude - i.e. safe

But of course if you map it at 5000 feet and then come down to sea level...........

[Sprocket]

Which brings us directly to Barometric compensation. Can some one please confirm how this feature works with Alpha N

[gunni]

If you unhook the WBO2 sensor nothing fuel wise will change except if it tries to run closed loop

This is only true if you run a MAF or MAP based system.

If you are using TPS as the load input, the reduced air pressure at altitude will not be compensated for.

Fortunately the effect is to deliver more fuel than is needed as you go up in altitude - i.e. safe

But of course if you map it at 5000 feet and then come down to sea level...........

I was only mentioning it in relations to the Lambda table.
that it is not needed for the lambda table to work right.

[smurfinator]

we could all use a little more info on this, it seems.  Where I live now, I can easily see a 2000-4000 foot change in altitude in 30 minutes to an hour...  So, GInt, do you think that sensore really knows what is going in?  In that case, I'll have to revert my calibration back and re-map the engine  

But I meant to have new injectors soon and re-map it on a dyno anyway.

[rob@vems.co.uk]

You're using MAP on your Audi aren't you?

[GintsK]

Hi!

Here is quote from BOSCH datasheet:

9.13  For physical reasons the sensor needs ambient air at its reference gas
side. Replacement of the air volume inside the sensor must be guaranteed by
a sufficient air permeability of the wires and the connectors between sensor
and ECU. The breathability should be higher than 1 ml/minute at a test
pressure of 100mbar.
The current Bosch LSU connector is available with an integrated pressure
compensation hole with a permeable membrane, which guarantees a sufficient
air supply. This hole must be saved from deterioration as wax, oil etc.

No other mentions about pressure.

Datasheet can be reached here: http://www.not2fast.com/instrumentation/Y258K01005e03mar21eng.pdf

[smurfinator]

You're using MAP on your Audi aren't you?

Yes