RE: Mass Flow Meter Implementation and Emissions (long)

["Shah, Anand" <anand.shah@xxxxxxxxx>]

I just took my 88 M5 through emissions testing here in New Mexico, and as
Jim C 
pointed out in reference to the 944 Turbo post, my car got past the sniff
test, 
it didn't pass. Jim is completely correct in that the system is user
adjustable 
and thus no knowledgeable emissions inspector would pass it.  I kind of view
it 
in the same vein as a good equalizer for a stereo; you tune it so the entire

system matches your needs and then leave the settings alone until something
in 
the system changes (like a new exhaust/header).  The you re-calibrate.  Of 
course if I lived in CA I would simply put the air/fuel ratio LED and ARC2
out 
of sight; I think it would be near impossible for anyone unfamiliar with the

exact appearance of an E28 M5 AFM to know anything was different.

Out of curiosity I dug out the two year old emissions slip for the car  and 
compared it to the present one.  I don't have them with me and if anyone
likes I
can report the actual numbers.  In any case I have no real clue as to what
they 
mean or what the repeatability/calibration specs of New Mexico air care
stations
are, or how NM compares to CA.  I can say this: the present configuration,
with 
a Jim Conforti chip and Split Second MAF/ARC2 kit the way I adjusted it, has

WORSE emissions than the bone-stock car based on the results (I did not
lean-out
the car before testing).  Note this is a ten year old vehicle with a ten
year 
old cat and O2 sensor, but I believe the difference between modded and
un-modded
(and I would bet it is NOT the chip).  The only readout that looks
significantly
worse is CO at idle.  This may be a direct result of what I see as the only 
shortcoming to the Split Second setup - I experienced some stumbling when 
starting from a stop when cold, and some low popping when decelerating.  To
cure
both of these I increased the richness of the mixture a bit at low rpm.  The

high rpm measurements (~2200 rpm!?) looked "clean" and compared well with
stock 
car measurements, but were all slightly higher.

So I find this to be an excellent modification - I do feel maybe slightly
guilty
that the idle emissions went up.  The "illegal" factor doesn't really bother
me 
(unless of course I get caught and have to pay a large fine - I knew the
risks 
and took them).  Most engine mods and speeding (and even many satisying
sexual 
positions in some states) are also illegal; just know what line you are
crossing
when you do it and accept consequences.  I always like to remember that the
law 
is not about right and wrong, it is about legality.  A Jim C chip still
seems 
like by far the best and most cost effective mod (and still technically 
illegal?) that can be made to an E28 M5.  Aside from the cold hesitation,
the 
car has much better throttle response at all rpm and much better high rpm 
performance with the MAF conversion.  If you do a MAF conversion in a
vehicle 
that has an AFM that is not restrictive like that on the M5, I don't know if

there would be much if anything to gain for your $900.

- - Anand
88 M5
93 Corrado SLC

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