A6 2.5 TDI: No Power? Troubleshooting Guide

Hello everyone,

After the timing belt broke, I had to have the engine replaced in the aforementioned vehicle.
The workshop then installed a used (15,000 km) engine block from a T4 into the Audi, using the original Audi components for the attachments.
However, increased wear was also detected on the turbocharger compressor wheel, and while it was being replaced, a different one was installed at the same time. The only thing is that this one was slightly smaller in diameter!!!???
That's what the workshop stated, anyway.
The car hasn't been pulling properly since the repair was done.
'No herring will leave the plate when it's cold, but it will when it's warm.'
170 km/h END!
Now, they want to install a larger compressor wheel or a different turbocharger for me again.
It might also be interesting to note that I recently had the error memory read and cleared, and the car seemed to run slightly better afterwards (at least, that was my impression). According to the mechanic, several errors were stored in the error memory.
The boost pressure was at the lower end of the tolerance range.
Could someone please explain to me what's going on here?

Best regards, bramme

I believe you can probably answer the question yourself .

The workshop installed a smaller impeller.
2. There was also something in the error memory, indicating that a tolerance limit had been exceeded.

It probably has something to do with the turbocharger pressure.

Given that your question suggests you don't have much knowledge about the matter, go to a workshop and have the error fixed. Because if they install something like that, they should be responsible for it working correctly. 1

Hello Bramme,

What kind of workshop was that? I've never seen such nonsense (smaller impeller). Have them restore the turbocharger to its original condition and try to get some real data (use a VAG-COM or, if necessary, have a diagnostic test performed with all the important parameters).
The most important things are:

- Boost pressure
- Injection quantity
- Air mass
- Valve timing

Is the engine code still the same after the engine replacement? If not, was the vehicle identification number (VIN) also changed?

Hello Marco,

I just learned from the workshop that the engine code is no longer the same, and the mileage has not been adjusted.
Supposedly, everything has been adjusted.
Is it really that simple?

bramme

Of course, that's not so easy.
Different letter codes correspond to different control units.
In very rare cases, that works.
It's best to take it to a workshop and have them fix it, including the turbo wheel.