[Diy_efi] Wide band sensor, F1

[Mike]

At 03:01 PM 8/22/05, you wrote:
>I would say "no", assuming you mean the usual WBO2 sensor used in petrol engines.  I have two reasons:
> 
>1.    It's calibrated to provide a response which, while almost linear immediately about the stoichiometric mixture for petrol (c. 14.7: 1? memory fails) its response goes rapidly non-linear on either side of that figure.  Diesel engines, AFAIK, run in a regime where there is always excess air to burn the fuel which is expected to be metered by the injection pump.  So the sensor would be stuck "on the end stops" of its response curve.

Damn good point, I forgot all about this, power=fuel, not air flow based.

I should have known as the first thing I did in Malaysia was rent a diesel
with turbo and jammed the wastegate off - tut tut...

>2    Even if the injection pump is injecting excess fuel which cannot all be burnt, it tends to come out the exhaust as fine particles of carbon rather than as unburnt fuel, which is what the sensor is looking for.  I'm not convinced the sensor would notice, because of the different combustion process (chemically and physically) going on in a diesel.

mmmm Surely though if there is excess fuel any O2 sensor will indicate
when (allowing for response time) and how far assuming it isnt jammed up
against the 'rich' stop so quickly... ?

So under those conditions would a wideband show lower than  say 11:1
and not have its judgement clouded (pun) by soot particulates ;) ?

ie. Even though its nonlinear wouldnt it be mappable, ie Calibrated to give
a known output, with an error margin, at extreme ends of the scale, its been
a long time since I looked at any O2 sensors admittedly...

I wonder what they use for F1 (or do they) when running 4:1 or is it
with that exception so they use such very rich mixtures just to cool
the exhaust valves at selected parts of the race when acceleration
isnt that important,



Regards from


Mike
Perth, Western Australia
VL Commodore Fuse Rail that wont warp or melt !
Twin tyres for most sedans, trikes and motorcycle sidecars
http://niche.iinet.net.au

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