Re: What Air to fuel ratio should a 16v run . ?

[Mark Shaw <autox@inficad.com>]

XXSpArCoXx@aol.com wrote:

> OK onelast time for everyone.
> After messing with the car replacing some worn components We finaly
> got the
> car to barely run 14.7:1 WITH the full throttle switch on.
> Now when the switch is OFF I run Lean.
> Now I want to run 14:7 or at least really low 15's  cause the car runs
> lean at
> idle and almost anywhere else unless the full throttle switch is open
> and
> thats where it will run the 14.7:1 to 14.3:1 range.
> Now all I want to know is how to richen my mixture But a list meber
> was kind
> enough to truly tell me how to do this so I'm off to VW to buy the
> proper
> tooling now.

Ah, ha...better explanation of problem.

>From your earlier post I assume that you are measuring
your air-fuel ratio at the tailpipe, since you have no cat.
Is that right?

If so, then I would suspect that your oxygen sensor
and/or its wiring have gone bad on you.  Having
a high impedance or open wire may make the
control module think that the mixture is too rich
and to try and lean it out.  When you engage the
full throttle switch you override the O2 sensor
with a richer mixture.

Find the wire to the oxygen sensor.  If the O2 sensor
has one wire it is easy, otherwise you have to find
the green wire (the red/white one is the heater).
If you ground the green wire to the engine block
the controller will think the mixture is too lean
and force the control to the rich mode.  If this
cures the problem, replace the O2 sensor.
The other check is to monitor the green wire
to the O2 sensor while the car is idling with
a high impedance voltmeter (preferably the
analog scale type, not digital) and see if the
voltage cycles between about 0.1 and 0.9
volts once or twice a second.  If not the
sensor may be worn out.

If your control module and O2 sensor are
running properly you should be at 14.7
all the time unless you are under full throttle
or the engine is cold.

Sorry for hassling you about this earlier,
but without a complete description of the
model year, engine type, test method, and
all the symtoms, we have to make guesses
on what is really the problem.

regards,

Mark



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