1990 200 missing/lean under boost

[Louis-Alain Richard]

And don't forget that a standard (narrow-band) O2 sensor is useless if
mixture is not very close to stoich. So, in a case were the engine is either
too rich or too lean, a NB mixture gauge hooked to a standard narrow-band O2
sensor won't tell you anything. In some case, a rich engine will show lean
condition on a mixture gauge. Something like unburnt fuel will be monitored
as excess of O2, hence lean condition on a gauge but not in the engine.

There are many articles on that subject on the web. 

Louis-Alain


-----Message d'origine-----
De : quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com] De
la part de David Yentema
Envoyé : 8 juin 2011 20:33
À : audi at humanspeakers.com; quattro at audifans.com
Objet : Re: 1990 200 missing/lean under boost

Thanks huw, I honestly always mix those up.

Assuming a working fp, regulator, etc, control fuel pressure should remain
relatively constant during accelaration, correct?
On Jun 8, 2011 8:01 PM, "Huw Powell" <audi at humanspeakers.com> wrote:
>
>
>
>> Tony, from what I understand about o2 sensors, is the measure
>> presence of oxygen, not fuel. A lean mixture will result in less
>> oxygen, and a rich mixture in more. A misfire would mean more fuel is
>> unburnt, resulting in less oxygen, showing lean. If I am wrong,
>> please correct me..
>
> You are correct that they measure oxygen, then you got all the rest
> exactly backwards. Lean = more oxygen, rich = less. A misfire results
> in more oxygen, since it didn't get used burning fuel.
>
> Huw