Wastegate 2.5 TDI (AEL): Questions & Answers

Since I've been experiencing occasional power interruptions when the engine is under full load, I took a closer look at the turbocharger this weekend.

An expansion was not possible without major issues, so I disconnected the hoses and oil lines and blew compressed air (1.5 bar) into it. During this process, I could clearly hear the wastegate's pressure relief valve opening and closing. Can I be reasonably sure that the valve will also function correctly during operation (when the solenoid valve opens)?
According to the Audi mechanic, the malfunction of the solenoid valve should be recorded in the error memory, but that memory was empty. So, it should be working, right?

Best regards,

Hannes.

Hi,
At 1.5 bar (overpressure), this cannot be guaranteed 100% during operation because the pressure in that area comes from the intake system, which is normally a maximum of 1 bar. This does not account for short-term pressure spikes.
Therefore, if a part of the rod is jammed in a way that requires a pressure of only 1.5 bar to overcome it, this would lead to malfunctions during operation.
According to my understanding, the control unit can only detect short circuits or open circuits. If the LDR valve jams and does not open as much as the duty cycle dictates, this will remain hidden from the control unit.
If a data acquisition device is not available, I would measure the voltage at the LDR during the ride and, if possible, also the boost pressure using an LDA sensor or a regular pressure gauge. "Desperate" attempts by the control system to reduce the boost pressure would then be recognizable.
To measure the voltage, I once tapped into the two connection wires myself using pins, but being careful to avoid short circuits.
Christian.

Well, there were 1.5 bar at the pressure regulator, then there's about 10 meters of air hose, and I couldn't perfectly seal the tip of the air gun directly onto the pipe. So, it must have been less than 1.5 bar that actually reached the turbo.

I heard a distinct clicking sound, so it seems to me that the mechanical part should be working correctly, or am I mistaken?

Best regards,

Hannes.

It sounds a bit different now. Based on my feeling, I would say the wastegate is probably okay, and we should look for the problem somewhere else. Besides, other people have already had issues with defective LDR valves.
Christian.

Hi,

Yep, that actually sounds less like a mechanical defect.
I would also suspect the magnetic valve for boost pressure regulation or the mass airflow sensor.
Of course, the fact that no error was logged is a drawback.
If you have the opportunity to test drive the parts (without any obligation to buy, which sometimes happens), I would suggest giving it a try.