extreme lean condition at high boost.

[Bernard Littau]

Another item that is relatively easy to check is fuel flow.  You may have
good idle fuel pressure, but may be loosing fuel pressure at load.  Any of a
clogged fuel filter, a clogged fuel pump intake, or a weak fuel pump could
be a problem.  How noisy is your fuel pump?

The fuel flow test is fairly simple, just disconnect the fuel return line to
the tank (near the fuel filter) and route it into a suitable container.
Energize the pump and let if flow for the time spec'ed by Bentley Manual.
Measure the amount and decide if flow is good or not.  I don't have the
Bentley handy, so maybe someone else can chime in with the specs.

Bernard

On 10/24/06, Huw Powell <audi at humanspeakers.com> wrote:
>
>
> > Yea, but if all the other systems are delivering fuel, somewhat
> > proportionately to airflow, why would it go "off the scale lean"
> > suddenly? It sounds as if something is either reducing fuel delivery or
> > abruptly stopping it at a certain rate.
>
> Is that a reason not to check the WOT switch?  It's easy to check the
> switch, a slight pain to check it from the ECU end, but still a low
> impact (on the technician) test to eliminate one common failure item.
>
> >>> As soon as I put on the accelerator hard, it goes off the scale to
> >>> the lean side--which is dangerous to the engine at boost.
> >>>
> >>> I've got all new injectors on the car, good fuel pressures, good ISV
> >>> and known good warm up regulartor.  Any ideas?
> >>
> >>
> >> Test your WOT switch, connector, and wiring.  It tells the ECU to go
> >> rich once you are past a certain point of pedal motion.  If it's bad
> (or
> >> not talking to the ECU...), this could explain your problem.
>
> --
> Huw Powell
>
> http://www.humanspeakers.com/audi
>
> http://www.humanthoughts.org/
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