NGK UEGO sensors

[robert dingli]

Jonathan writes :
> 
> robert dingli writes:
> > The NTK sensor which is useful for AFRs from 10 to 30:1 which costs close
> > to Aus$900 and the wide band Bosch unit which is wide band only in the lean
> > region and cost around Aus$250.  The Bosch unit operates as a voltage source
> > as do normal EGO sensors.  I'm not sure how the NTK unit (nor the Japanese 
> > UEGO sensors fitted to production cars) work.
> 

Note  NTK (above) should read NGK.   :-)

> I'm not familiar with the sensors that the Jap lean-burn stuff use.
> I have used the NGK UEGO (it was US$1000 back then) though.  The useful
> range is actually a Lambda range, the AFR range will depend on the fuel
> you are using.  I was using the sensor with a Horiba MEXA-101L and it
> worked GREAT for tuning!  It has two problems that I can think of for
> feedback control use, though.  First, it's useful life is somewhere
> around 200 hrs.  The second is that has to go through a 30 second
> burnoff cycle each time you turn it on, so you can't just turn it on
> when you get near WOT (I'm going by the Horiba owner's manual on this
> one, someone please correct me if this isnt really necessary).  I have
> heard of at least one person doing closed loop under transients with
> the NGK's on marine race motors.
> 

I colleague of mine tested the viability of using individual NGK sensors
in each of eight exhaust runners in a 5 litre Group A Commodore.  As part
of an initial test, he placed all eight sensors at the same point in an 
exhaust stream only to find that they each required individual calibration
as a function of temperature (I'm not sure of the specific problem here).  
Anyway, he later settled on using one sensor with individual exhaust 
tappings from each of the runners.  His concern was balancing the eight 
cylinders and thus only the relative AFR was important.

Robert
-- 
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             Robert Dingli           r.dingli at ee.mu.oz.au

Power and Control Systems                 Thermodynamics Research Lab
Electrical Engineering                    Mechanical Engineering
   (+613) 344 7966                           (+613) 344 6728
  University of Melbourne, Parkville, 3052, Victoria, AUSTRALIA
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