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Switchable O2 Input / 2x Narrow & 2x Wideband, possible ?


Dynodom
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Hi

Vehicle: GTR R32

We are having to pass EURO2 emmisions test on this Vehicle. (Failed once already)

For this purpouse, I am using the two factory narrowband O2 sensors for Cat precision, mapping very closely to Lambda-1, in closed Loop NB dither mode. 

 

The exhaust system is also equipped with two Link Can2Lamdda modules, not yet connected though.

Is it possible on the Xtreme G4+ system, to use both, NB and WB sensors, by defining a switchover point, ie Map or TP or LA-target based, so that NB O2 sensors would be used in all areas where Lambda-1 is the target and all richer target areas would use WB ?

 

TIA

 

 

 

 

 

 

 

 

 

 

 

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There is no way to switch between narrowband control and wideband.  However, narrowband cant do anything a wideband cant.  If you use the "Stoich Mode  (wide band)" CLL mode then the CLL works like a traditional narrowband by dithering the fuel mixture 0.02 lambda either side of target.  So if your target is lambda 1.00 it will work just like a traditional narrowband.  

Then say above 100kpa you can target a richer mixture.  It will still dither either side of target but 0.02 lambda would not be a concern for most.  This mode is typically a bit slower at high loads than the auto mode however.  

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Hello Adam

In response to your elaborate answer, I have one more question.

<<However, narrowband cant do anything a wideband cant.  If you use the "Stoich Mode  (wide band)" CLL mode then the CLL>>

I am aware of that. But, isn't a narrowband sensor more accurate, respectively faster responding at L1, compared to a linear wideband signal?

D

 

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Not significantly as far as I have seen.  The system doesnt even need to be particularly fast, most OEM CLL systems only oscillate at 5Hz or less.  I think the main reason for narrowbands in older OEM's was cost - it was the cheapest way to achieve the objective.  Most modern cars have changed to wideband sensor pre and post cat now as emissions output has gotten more stringent.

A wideband has exactly the same narrowband nernst cell inside - it just has an oxygen pump cell working beside it at the same time, when you are at L=1 the oxygen pump is doing nothing.     

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Hi Adam

One more question  came up.

What is the function of the afr target table in Narrowband stoich mode?

Is it still being looked at by the ECU in the Background?

 

Load Input for Fuel is Alpha N, TP by the way.

 

Thanks in advance.

 

 

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In Fuel Main settings if "Open loop lambda table" is set to on, then the lambda target is taken into account as part of the fuel equation - much like a modelled/VE type strategy.  Ie You can change the target lambda later after tuning and the mixture should follow without needing to retune the fuel table.  The target table will always be used for CLL target regardless of this option being on or off in wideband stoich mode.  

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