Turbocharger Wastegate Valve Not Working?

hello

Regarding the vehicle: T4 TDI, ACV engine, manufactured in 2000, no VTG turbocharger.

I installed a new charge pressure control valve today because the old one was no longer working.

'I identified the fault using a Bosch tester, with the engine running and all external connections made. Everything is working correctly, including the AGR magnetic valve, with no issues. The turbocharger pressure control valve, however, wasn't responding. For safety, I connected a different AGR magnetic valve to the connector of the turbocharger pressure control valve, and it works; it's being activated.'

I only connected the AGR valve to the connectors because it's a vacuum valve, and the boost pressure is controlled by an overpressure valve, not directly to the lines.

Okay, now the problem is that the new wastegate valve isn't working either. The pressure sensor is clear, and I've checked all the lines with a small hand pump.

Are there any other possibilities? Does anyone perhaps have a diagram of the wiring and connections? Maybe something is missing, or perhaps there's too much. There's an intermediate connector/wire extension in the line leading to the control unit, and I'm not sure if it belongs there.


I don't have any error messages either.

I logged something, but I was alone and just pressed the 'start' button, which seems very strange to me.


Thank you, Peter.

Hi Peter,

I'm not entirely sure, but with the 1Z (also a wastegate turbo), the boost pressure cannot be adjusted through the diagnostic system. The N75 valve is only activated after the bypass valve. But you can hear it clicking.

The valve is just a simple 12V solenoid valve, so you should be able to connect a 12V LED to the contacts; that way, you'll be able to see it blinking clearly.
On the other hand, if you connect the battery directly to the MV (main voltage), it should work.

If it's blinking and clicking, the only possibility left is that you've swapped the signal cables (which is quite easy because the MV units aren't as clearly labeled as the VTG MV units (VAC, Out...)).

Here's another picture with your information:

hello

@martin

Thank you for the diagram.

The valve is ticking, quietly, but it's ticking.

@all

Okay, so I tinkered with it again this morning and went through everything.

- The connections are definitely connected correctly; I even disassembled another ACV for safety's sake .

- Checked the wiring again.

- Now, here's the important part: just to be safe, even though my EGR valve is clean and working, I disabled it using a plate, and sure enough, things have improved significantly. The turbo lag is less pronounced, the throttle response is better. I suspect it's simply responding too slowly.

The values have significantly improved, however, I still have a problem: the boost pressure builds up slowly; it always lags behind, although it does eventually reach full pressure.

The most interesting thing, as mentioned in yesterday's log, is that the boost pressure never reaches the target value when idling. Even when accelerating while stationary, it sometimes lags behind by 0.3 bar. What could be the cause of this?

My idea is that the printing bed is leaking, unfortunately I don't have a pressure gauge:oops:, but I will get one.

Next idea: boost pressure sensor. What do you think?

peter

My 1Z also doesn't have the correct pressure at idle either.

Otherwise, my log server is currently down, so I wouldn't be able to provide comparison graphs.

Thank you to the person who set their Wi-Fi router to the same channel as my provider .

m;

Okay, then let's wait and see, and have some tea.

If yours isn't delivering the expected boost pressure, that's already a good sign. However, I still have the small problem that the boost pressure lags behind, but okay, maybe someone with an ACV can log some data. Or someone else.

Thank you for your help.

peter

Hello Peter...

The MSG itself measures the pressure.
There should be a pressure line connected to it (a thin, fabric-covered hose, like the oil drain lines).
Possibly, this line is damaged or clogged.
The altitude correction factor should also be considered if the boost pressure is consistently below the target value across the entire speed and load range.

Regards,
Steve.

Quote:

When accelerating from a standstill, it sometimes lags behind by 0.3 bar; what could be the cause?

Normal... and without any meaningful information. Boost pressure must be measured under full load.
IMHO, but back then, he looked completely normal.

Best regards, Rainer.

The MSG itself measures the pressure.
There should be a pressure line attached to it (like a thin, fabric-covered hose, similar to the oil drain lines).

Does the 2000 T4 not have...?

if the boost pressure remains consistently below the target value across the entire speed and load range.

That's not the case; just look at the table or the diagram.


The boost pressure must be measured under full load.

'Yes, I have those values, but they are worse compared to previous values, and the fact that it was performing so poorly even without any load is something I haven't seen before.'
I will try to create more visually appealing logs and then post them.



peter

hello

Today, I did several runs, including measurements using K-Power.
The diagrams and tables regarding the charging pressure are in the appendix (how can I include them?).
The boost pressure builds up very slowly and only reaches the target value at one point. At this point, which is also visible with K-Power, the maximum torque is reached. However, it then drops off just as quickly as the boost pressure.

The maximum power output is, on average, 140 horsepower, and the maximum torque is 355 Nm, values that also correspond to my measurements on the dynamometer.

The problem here is that the torque range I'm familiar with from previous measurements is larger.

'Where could the problem be? Something else that occurred to me is that it might be the cat (catalytic converter), or the rubber ring that seals the plastic pipe on the intake side to the turbo, or a leak on the pressure side, but I think that's unlikely.'

Your opinions are needed again.

...or did I make a mistake in the measurement?

Thank you, Peter.


I've attached some additional information, including a table with all the values. I logged the LMM (Pierburg) and the turbo.