4000 q goes lean on throttle

[R Mangas]

Hi John-

   Dunno for sure, but I'm not certain that unplugging the thermo sensor
qualifies as 'open-loop'; I think that the ecu may see that as a really cold
engine.

   Have you verified fuel delivery volume in addition to pressure?
   What about air meter plate freedom of motion?

   Where are you located?

Robert, Detroit




>From: John Booth <jrbooth3 at yahoo.com>
>Reply-To: jrbooth3 at yahoo.com
>To: Quattro <quattro at audifans.com>
>Subject: 4000 q goes lean on throttle
>Date: Tue, 11 Feb 2003 21:00:27 -0800 (PST)
>
>I have replaced with new or remanufactured the
>following
>isv
>fuel distributor
>fuel filter
>o2 sensor
>water temp sensor
>idle and full throttle switches
>I have checked
>idle to bentley specs.
>fuel pressure
>diff pressure regulator
>The problem I am having is that at idle the mixture is
>fine and the car runs great. At anything above 2000
>rpm the car goes lean 16.5 to 1 on the air/fuel gauge
>with the car in closed loop. It will surge with power
>and the mixture will jump up but then the car goes
>lean again. In open loop (I disconnect the water temp
>sensor) the car runs ok but rich (12.5 to 1). It seems
>that the o2 sensor is bad but it shows fine on the
>gauge and I can see the 4.5 volts from the ecu during
>warmup so I think the wire is fine. Any help off line
>would be great. My only other thought is to buy an ecu
>and try swapping it out.
>
>John
>
>=====
>John
>Driftunderground.com
>Midwest drift racing
>
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