Re: used cats

[christian147@domain.elided]

>I will have the Autronic SMC which has closed loop and a wideband
>sensor input, which I think is much better than many mid '90s motronic
>EFI system.
>I guess it would be kinda strange why an EFI
>with a knock sensor, wideband O2 sensor input and a very high
>resolution map capability 
Here is asn excellent example why it is not allowed.  To what CLV(
calculated load value) do you allow the system to run closed loop?  It is
one of the programming parameters.  Manufactures suggestion is not more
then 20%.  How much do you allow the loop to adjust the map values? 
Again programing parameter and suggestion is not more then 3%.  With
Autronic, Haltec or EFI332 for that mater, the imputed fuel map is in
effect a V.E. map.  What A/F ratio you try to maintain is probably going
to  from the brake at high load and gas mileage and engine feel at low
load.  I have never seen a dyno shop with a BAR 90 gas bench, let alone a
reliable NOx sensor.  When you write the low load map did you use a
portable 5 gas bench?  With no EGR we can only control NOx  by cooling
the burn with more fuel, the cat can't handle more then about 550ppm NOx
and if you don't control temp and pressure the engine will make 4000-5000
ppm.  Does the cat have the extra capacity to handle the extra HC and CO
form the cooling fuel?  EPA compliance test ensure the manufacturer got
it right,  enhanced I/M testing doesn't ensure you got it right.

Smog inspections are not designed to catch all out of compliance cars,
the test are designed to catch 90% in the cheapest and easiest way
possible.  The loaded tests (IM240 and ASM)only test about 20% of the of
the EPA regulation.  To add to that the gas benches used are far from
"lab quality".  ASM's  NOx sensor can only detect NO , it extrapolates
NO2 from an assumed equilibrium.  It works pretty well in most cases.  

The people who wrote the inspection regulations are aware of the cost and
inconvenience they are causing, and they do do cost benefit analysis, so
what we as consumers have to put up with is nothing compared to what the
manufacturers have to go through

Chris Hall
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