Audi 80 TDI sleems sluggish on acceleration

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chip_one@hotmail.com - 08 Sep 2006 13:34 GMT

My 1995 Audi 1.9TDI seem sluggish on acceleartion and loses power on
hills.

Checked the ecu with a Geniscan code reader pointed to the Manifold
absolute Pressure sensor.

Cleared the fault and went for a spin, acceleartion seemed Ok.
Coming to work this morining seemed slow again, Checked again it was
the same MAP error.

Question where is on the engine, could it be the electrical module that
has three vacumm pipes connected to it, One from the waste gate
actuator, one from the turbo inlet pipe and the other pipe lookes like
it comes from the botton of the housing.

when the igntion is switched to position 2 it makes a ticking noise,
although it does seem to tick a bit quieter and less frequency.

Thanks

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Tim.. - 08 Sep 2006 13:51 GMT

> My 1995 Audi 1.9TDI seem sluggish on acceleartion and loses power on
> hills.
[quoted text clipped - 13 lines]
> when the igntion is switched to position 2 it makes a ticking noise,
> although it does seem to tick a bit quieter and less frequency.

I would put money on the fact that your AMM is the root of the problem,
especially if there is no smoke under hard acceleration, just reduced power.

Tim..

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chip_one@hotmail.com - 08 Sep 2006 14:14 GMT

I will disconnect the Air Mass module to see if the fault remains the
same, i remember a few years ago when the AMM was disconnected it was
awfull to drive, its not that bad.
Can the performance vary that much with speed, after i have reset the
ecu is seems alot better like it was in limp home mode,no lights on
dashboard and no smoke.
Seem strange its pointing to the MAP sensor, which is why i was asking
the question where it was.
will look at buying one, i know they are expensive.

Thanks

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M Cuthill - 08 Sep 2006 21:03 GMT

>I will disconnect the Air Mass module to see if the fault remains the
> same, i remember a few years ago when the AMM was disconnected it was
[quoted text clipped - 5 lines]
> the question where it was.
> will look at buying one, i know they are expensive.

The engine management uses the values from the MAP, MAF and Crank sensor to
carry out vairous calculations to check the integrity of the data.

By using the MAF and RPM sensor, the ECU can calculate roughly what the MAP
sensor should be.
And likewise by using the MAP and RPM values, the ECU can calculate roughly
what the MAF should be sensing.
With either MAP or MAF faulty, the ECU will know that one is wrong, but it
has to guess what one.

Off course, by using a live data read out, any competent technician can soon
tell which one is faulty, even though the ECU may of picked the wrong one.
Fault codes are not the be all and end all of vehicle diagnostics. They only
point you in the right direction, which in this case is a fault lying within
the inlet air system. And given it's a VAG vehicle, then it's 99% likely to
be the MAF.

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chip_one@hotmail.com - 11 Sep 2006 15:24 GMT

Fixed the car over the weekend.

It turns out it was the MAP reporting the correct fault.

Managed to locate the MAP sensor, this was located in a long black
plastic manifold pipe under the turbo. Checked the Map sensor this was
connected, however after checking the plastic pipe for splits i
discovered a split in a rubber hose that connects between the plastic
pipe and the top inlet manifold next to the EGR valve. After i replaced
the large 60 mm diameter pipe the acceleration was ok and no loss of
power up hills.

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