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Re: O2 sensor readings-correct?

> I put a digital voltmeter on my O2 sensor the other day, and here are the
> numbers I got. Tell me if you think (or better yet, know) whether this is
> right.
> Here's the background:
> 84 4000S quattro.
> Has good power, but seems to miss a bit off idle, jerks at 2000rpm,
> doesn't start as well as it used to, and I've never been happy with the
> gas mileage.

try new plugs, cap, rotor, maybe air filter.

> O2 sensor is a generic 3-wire, with less than 10000 miles, no vacuum
> leaks (I think).
> The data:
> engine cold, idleing or driving: 0.5 volts (I assume this is a bogus
> signal generated before the sensor warms up).
> warm, idleing: wanders from 0.2 to 0.7 volts, occasionally outside this range. * that's good
> warm, throttle closed, 1000-2000rpm: 0.7-0.8 * weird.  you mean if you give it gas the voltage goes up and stays up?  That's running rich.
> warm, throttle closed, >2000rpm: 0 * and that would be lean.  both of these are wrong, should still wander...
> warm, driving: wanders like the warm idle, but stays closer to 0.5. * that is good.
> full throttle acceleration: 0 at low rpm (2000) rising to 0.7 at high rpm
> (4000).
> Does this mean I'm leaning out at high RPM? Time for new filter?  * I just checked Probst to make sure... higher voltage is rich, that is what WOT is supposed to do, open loop forced slightly rich.

except for those two middle readings all seems ok.  How do you get 1-2k
and > 2k rpm with the "throttle closed", btw?

Huw Powell


82 Audi Coupe; 84 4kq; 85 Coupe GT