I'd like to take advantage of the collective wisdom =
of The
List. I need some basics on the operation of the digifant =
system. I
too have had problems with the lumpy idle, stalling etc. I have =
replaced
everything except the AFM (which checks OK with a cheap digi =
multi-meter) and
the computer. I have messed repeatedly with the "don't even think =
about
touching this" , mixture screw. I finally decided to experiment on the =
AFM with
the adjustments that are found on the "wiper" under the small plastic
cover. Tried changing spring tension. Looser (allowing wiper =
to move
more for a given volume of air) helped some. Changing the position =
of the
wiper contact relative to the air flow vane (richer) helped alot, =
**but** only
with the 02 sensor disconnected. When I reconnect the 02 sensor,
everything returns to crap. The easy answer is that I need to =
replace the
02 sensor right? Did that 2 years ago. Ran like crap before =
and
after the new sensor. While doing my experimentation, I have =
connected the
multimeter to the 02 sensor output (while sensor is disconnected from =
the
computer). It is working. All of the basics are correct: no =
vacuum
leaks, good ignition, new fuel filter, idle stabilizer, =
etc. The
static timing is advanced @ 5 deg. Makes more power this way, =
and
does not seem to effect anything negatively. The engine =
really only
wants to run well when the 02 sensor shows that it's running very rich: =
.80 to
.90 mv. At this setting, it really does run well. Steady =
idle, no
stumble on clutch release, no popping and kicking on decel, and gobs of =
power at
cruising speed. The question then is: why can I only get this =
thing to run
right when the injection is apparently too rich? Is this what =
VW
intended? Is this the only way that it would pass emissions specs =
or get
acceptable mileage? Does the 02 sensor provide input to the =
computer
at all operating speeds/loads or just at idle? Does the C0 =
adjustment
screw affect the entire "map" of operation or just at specific =
speed/load or
when the 02 sensor is out of the loop? I am very happy with the =
way our
wbx is running now, but this setup is not right.
Why?