Re: Wheels & Upgrades

[ti@amb.org (Ti Kan)]

Ken Keith writes:
> Wait a minute, what car are we talking about?  I must've "fell" into this
> discussion, but it sounded like we were talking about a 4kcsq, but AFAIK
> the 4kcsq and C-GT have totally mechanical fuel injection, not controlled
> by a computer.

Although the K and KE Jetronic fuel injection system on these cars
is mechanical, cars made for the U.S. since 1980 had to be equipped
with oxygen sensors and closed-loop fuel-air mixture control, therefore
an electronic control unit is necessary to achieve this.

In the early K Jetronic cars, this was accomplished by varying the
fuel pressure in the fuel distributor's lower chambers using a
frequency valve, which is controlled by the ECU.  The ECU would
vary the duty cycle to change the fuel-air mixture, based on input
from the OXS sensor, as well as a thermoswitch (which sets the
system in open loop enriched mode when the engine is cold), and
a full throttle switch (enrichment on full throttle).  There is
also a separate control pressure regulator that is used to provide
gradual enrichment during warm-up.

In the later KE Jetronic cars, the frequency valve and the control
pressure regulator functions were supplanted by the differential
pressure regulator, located on the fuel distributor.

Most K and KE Jetronic cars have analog ECUs, except the Audi
5000S turbos and TQs from the 84 model year and up.  These cars
use the K Jetronic system, but have digital ECUs that also deal
with the ignition timing and turbo wastegate control functions.

So, the answer is: yes, these cars do have a "computer" that controls
the fuel injection.  For your 4KQ or Coupe GT, the ECU is located
under the dash, to the right of your glove box.

-Ti
96 A4 2.8 quattro
84 5000S 2.1 turbo
80 4000 2.0
-- 
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Research Laboratories, Sunnyvale, CA. USA
  ///    ti@amb.org
 //////  http://sunsite.unc.edu/~cddb/tikan/
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