Audi: Audi A6 2.5TDi Power problem

Hi Ed,

On 9 Feb 2004 05:56:32 -0800, co.uk
(Rugbytrader) wrote:
 
 
 

Did you have the air mass sensor checked? It's a device sitting in the
back of the engine compartment. The sucker is not wired into the
onboard telemetry, so an error is not recorded.

This thingie fails quite regularly on any TDI engines and the Bosch
one yours has (such as my 99 A6) does that equally often. Usually it's
due to moisture or oil fumes settling on the heated wire. Then it
gives a false signal (too little airmass reported) and the injection
system adjusts the fuel to the airmass it sees. ==> Reduced power.

A nice indication is if top speed is not reached. Another is, that at
around 2700 rpm you have a real drop in torque and you need to shift
down to speed up quickly.

The workshop should be able to determine a faulty sensor by attaching
the VAG computer to your car. Then they drive slow in third gear and
press the pedal to the floor. When spooling up, the airmass should
read something like over 800 at 3500 rpm (I posted it previously and
dont have it in the top of my head anymore)

Anyway, there is a test drive cycle they should be able to run. I'm at
my 4th sensor and there are Audi service bulletins on how the wiring
in the car should be changed so that the post-ignition heating of the
sensor wire is disabled.

The part is around 250 Euro here IIRC and is changed in less then ten
minutes with a screwdriver, but if you search the web, cheaper sensors
from mercedes (where only the sensor and not the complete assy is
sold) can be had. Never tried one myself, but it's _supposed_ to work.

HTH

Regards

Wolfgang
--
* Audi A6 Avant TDI *
* reply to wolfgang dot pawlinetz at chello dot at *

"Rugbytrader" <co.uk> wrote in message
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Probably the MAF (Mass air flow meter). Expensive to replace but a common
problem.

Check your exhaust smoke when you floor your accelerator in sixth gear. If
you see a cloud of smoke in your wing mirror and the MAF is OK, it's
probably a torn intake hose.

Check and see if your problem can be reproduced whenever you floor the pedal
on the same slope and long gear, and if there is a difference when you apply
gas gently all the way to the floor and when you floor it suddenly. If there
is a consistent difference and your problem only takes place when you floor
it suddenly, it could be that your hose is being strangled at maximum
suction, then it would be a matter of your having your hose replaced with
one that was not so flexible.

My father experienced something very similar in his '97 A6 2.5 TDI and the
VAG machine showed everything to be OK, when it was obviously not.

My two cents,

JP Roberts


"Rugbytrader" <co.uk> escribió en el mensaje
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