RE: Question of Air/Fuel ratio's and my Air/Fuel meter

["Fry, Larry" <LEF@chem-tronics.com>]

Keep in mind that neither the "best power" nor the "best economy" mixture is
going to give you the "best driveability".  There's no free
lunch....everything's a compromise. So, pick one.......:)

Larry  sandiego16V

-----Original Message-----
From: Randy B [mailto:sirocco@telocity.com]
Sent: Wednesday, October 24, 2001 9:47 PM
To: scirocco-l@scirocco.org
Subject: Question of Air/Fuel ratio's and my Air/Fuel meter


Ok, I have had a Westach analog Air/fuel meter in the car for about 1.5yrs
now.....not hooked up.
I *finially* hooked it up last week and am a little baffled as to what I am
getting with the readings.
The gauge is analog, 1/4 sweep needle, range 12:1 - 17:1 with 14.7 marked as
stoich.

When I initially hooked it up (with an old oxy sensor from my old Scirocco
that worked back then) I was getting reading of mid 16:1 under load and high
15:1 to low 16:1 while cruising (maintaining speed and load). After reading
Probst's Bentley Fuel injection book I attempted to adjust the air/fuel (by
means of adjusting the mixture next to the fuel distributor with the allen
tool) so that it would be at or around 12.6:1. According to him this is
maximum power with 15.4:1 being best fuel economy. As I adjusted it richer
and richer I did notice more and more power.

The problem is however that when the car is started cold it runs like a top
fuel funny car, missing and spitting and stumbling.
It used to start perfectly, and always ran very well (with a slight loss of
power).

And to confuse me even more...
I leaned it out a little and drove it tonight, after barely trying to keep
it running cold, and now it's reading ~16.2:1 under load and ~13:0:1 while
cruising. WTF???
Everytime I nail the throttle the gauge hard pegs at 17.0+:1 and slowly
comes back to 13.0:1 but if I go up a hill it will peg at 17.0:1+ and slowly
come back to ~16.2:1.

When I got home, I pulled the plugs (Beru Silverstones @ 28, indexed, with
Nology wires and coil amp) and all 4 had white powder on the arm and
surrounding area and black soot on the base where the arm comes up from -
sorry I don't know what these parts are called but I imagine you can
visualize it. The Oxy sensor also had white powder on it. This means it is
running lean right???

I switched the Oxy sensor for the one that used to be in the car and wired
it to the gauge. (Haven't fired up the car yet)
BTW, Westach says in their instructions that the signal from the oxy sensor
will not be affected as long as the provided size of wire is used....that's
what I used. A friend of mine and I bought these gauges from Ed Valvo (some
might know him) so I am positive it is a quality gauge and should work
right.

I guess my question (trying to figure this out) is what range should a guage
like this run in?
Is Mr Probst (fuel injection book) right that 12.8:1 is the magic #?....too
many variables to tell?
How do I get the system to run lean, seems the richer I make it the worse it
starts and doesn't seem to make much of a difference on the gauge.?
How do I get the gauge, ie.. system, to run a little more stable and give me
good cold start?

Sorry for such a confusing post but I am quite a bit confused. :(

Thanks for any insight,

Randy
81 Scirocco S (X2)
"The Twins"





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