Re: quattro-digest V4 #2353

[ptimmerm@mashtun.JPL.NASA.GOV]

PDQShip Wrote

> EGT measures may be the temp fix between fixed lambda WOT and a
> better O2 sensor.  What we really need is a better O2 sensor. EGT isnot
> really relevent to lambda, it is relevent only to WOT bypassed/fixed 
> lambda values.

It is possible to run a car to a fixed lambda at WOT if you correct
for the temperature effects that WOT has on the O2 sensor.  The O2
sensor will tend to show leaning out under WOT, due to heat, not stoich.
Trying to run closed loop will fatten it up too much.  Thus open
loop @ WOT being common.  Perhaps Audi has fixed this issue the only
way currently available at a reasonable cost, with an EGT.

The much more expensive wide range, O2 meters don't have this
problem, because the run a reference concentration cell to 
calibrate against (essentially).  They are too bloody expensive for 
any production vehicle.

paul timmerman