Re: CIS-E fuel modification @ WOT

[Tony Lum <tlum@flash.net>]

Hi gang,

Having started this thread, I feel some responsibility to say to those
considering altering the FI system to increase performance on NA I5
engines-DO NOT FOOL AROUND WITH THE FUEL INJECTION SYSTEM UNLESS YOU KNOW
EXACTLY WHAT YOU'RE DOING.  My original post also stated the same (that
this was mental exercise for now).  Performance gains may be very modest to
nil and at worst could ruin your cat (the one on your car silly) or as
Probst says, "in some circumstances high enough to light the car on fire!".

The initial idea of this mod came from my analysis of an write up of
Techtonics Tunings enrichment module added to a 16V Scirrocco with CIS-E FI
in EC magazine. Their measurement technique used a special high speed OXS
sensor to monitor AF mixture. The system FI "hack" was so easy it might be
fun to try on my 4kq. Only after re-reading my Probst did I realize that
this mod (altering the coolant temperature sensor circuit) is one of the
oldest in the book.  Section 8.2 of the Probst book covers exactly this mod
and its attendant risks.

Why screw around the engine in the first place?  Like many others on the
list who own both big and little quattros,  once you've started modifying
and increased the power of the Turbo I5, it magnifies the absence of same
in the NA I5.  Short of the complete MC engine swap (which is the correct
mod to do) but which also costs up to 4.5K, you're going to try every
little trick you can-exhaust, timing, air intake, etc.  Thanks to ScottMo,
Qship, Phil and others who possess far more knowledge than I, we can
usually count on their expertise to tell when you're about to run headlong
into blind alley.

Sorry for the waste of BW,

-Tony
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Tony Lum  (tlum@flash.net)                  1987 5000CS Turbo Quattro
Berkeley, California, USA                      1985 4000CS Quattro
Audi Owner/Driver/Mechanic by Necessity ;^)      1980 5000S Sedan     
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