TDI VTG/N75 Troubleshooting: Common Issues & Fixes

'My Lupo 3L 1.2 TDI is lacking power.'

From the VTG technical article:
Tip: Even at idle speed, the VTG (Variable Turbine Geometry) is set to the 'max' position. The adjustment lever must...
So, when the engine is idling, it should be at one extreme position, and when the engine is not running, it should be at the other extreme position.


In my case, this is not the situation; it is deactivated in both cases, even though there is vacuum in the hose leading to the pressure sensor when the engine is idling.

However, using the 'output test' function in VagCom, the VTG (variable turbo geometry) moves smoothly from stop to stop.

I also did some testing, and in measurement block 3, the target value for air mass increases to 1000 when accelerating, but the actual value only reaches 580.
That was in ECO mode, and in retrospect, I now think that the power limitation was implemented by setting unattainable airflow target values.

The actual boost pressure values corresponded to the target values.

Error memory is empty.

AGR set to minimum using VagCom.

hmm

If the actual air mass deviates from the target value, but the boost pressure is correct, you should try replacing the mass airflow sensor (MAF). If nothing changes and the actual value remains constant at 580 mg/h, I suspect a faulty MAF sensor.

'Where can I find the measurement blocks for the Russian border and torque limitation on a 1.2 TDI PD engine?'

http://www.dieselschrauber.de/Solldaten_3_Zylinder_PD.html

Does the target LM (likely referring to a lambda value or similar parameter) only exceed the actual value during acceleration, or is it permanently higher?

Am I misunderstanding something, Roger? Didn't he write that the setpoint is above the actual value?

Yes, when accelerating. It doesn't mention anything about driving at a constant speed.
When accelerating, the target value should anticipate the change, similar to how boost pressure works. After reaching a steady state, the two values should ideally converge. However, this information is missing.

"In my case, the target value also reaches exactly 1000 at full load. However, all values are achieved during constant driving. I believe that the 1000 value will not be reached even with a new mass airflow sensor (MAF), and it's more or less an unrealistic target set by the control unit. According to the repair manual, a value greater than 700 mg/H is specified as the target value at full load."
Therefore, I think that Rogers' conjectures are heading in the right direction.


Dirk.

Okay, yes, I see that. The 1000 also seemed quite high to me. However, the difference of almost 420mg/H bothered me and raised doubts.
So, I'll join now .

Otherwise, we'll just have to wait and see if we receive more information.

Now the weather is suitable for full-throttle acceleration again, and I'm going to do some test runs tonight.