1.4 TDI Turbocharger Problem: Boost Control Error 17964

Hello.

My A2 has the following problem:

1.4 TDI Engine Code: ATL, Error Code 17964: Turbocharger pressure control - regulation limit exceeded.
Mileage: 96,127 km
Chip tuning from *** Allgäu, with 90,000 km on the clock.

No more power, emergency mode (maximum speed of 110 km/h - acceleration from 0 to 100 takes minutes).
Engine control unit warning light is on.
Restart --> working perfectly again --> back in emergency mode.

Repair attempt:

All turbocharger boost hoses were inspected for cracks (nothing was found visually).
All vacuum hoses were inspected for cracks (nothing was found visually).
Vintage rod, smooth action.
Intercooler, visually undamaged.

Error still present...

On my way home, I kept encountering him (in a town, on a country road). Once I was on the highway, maintaining a constant speed of 130 or 150 km/h, everything was fine.
Get off the highway and drive the last 30km on country roads / through villages --> 5 restarts required .

Today, I wanted to examine the vehicle again, and lo and behold, the warning light was off, and the car is running as usual .

There's nothing visible underneath the car either. However, I consistently have 130 mbar less actual boost pressure than the target boost pressure when the engine is idling.

At higher loads, the difference can be either lower or higher.
Is this normal?

I also noticed that the throttle body is very dirty, and that oil has leaked out from under the vacuum diaphragm of either the throttle body or the EGR control valve.
The charge air hose is also attached to this valve via a swivel joint. This joint has some play --> is that normal?

"If anyone has any suggestions, I would appreciate it. I don't want to have to swap out the parts randomly."

N75 Vacuum Magnet Block 6Q0 906 625 G, approximately €132.
AGR valve: 045 131 501 K, approximately €115.
Control valve 045 128 063 G, approximately €280.
I was unable to find a replacement part for the connection fitting for the charge pressure hose and the control valve.
The T/p sensor, model number 038 906 051 C, costs approximately 44€.
A new loader costs much more.

I'm a bit lost.

For emergency operation, the LD (Light Curtain) fault must continuously exceed a programmed threshold value for a specific duration (usually around 5 seconds).
If you give it full throttle for only 4 seconds and then briefly release the accelerator, the emergency mode will never activate, even if the LD exceeds the measurement range of the sensor (although the turbocharger could fail at any time).

LD-limit errors in electronically controlled engines are usually caused by the tuner, either due to inappropriate LD-parameters or due to hardware problems in the turbocharger resulting from excessive exhaust temperatures or too much soot.

Quote:

However, I always have 130 mbar less ACTUAL boost pressure than EXPECTED boost pressure when idling.

This is somewhat unusual for typical defects in the turbocharger. It should only occur, if at all, when the engine is extremely cold immediately after starting, and the turbocharger is not yet spinning.
Are the air pressure and boost pressure the same when the engine is not running (Measurement block 10/11)?

Please log measurement block 11 (->upload to 'Upload') at idle and full load (1000-4000 rpm). Also, try logging it at 2000 rpm with no throttle, then immediately apply full throttle.

Best regards, Rainer.

Quote:

However, I always have 130 mbar less ACTUAL boost pressure than the TARGET boost pressure

.

That almost screams for a "cast" LD setpoint. Add 10% to the entire KF (control loop), and it should work...

Check if the catalytic converter is rattling. Excessive back pressure can significantly hinder the lambda (oxygen sensor) control system.

Quote:

N75 Vacuum Magnet Block 6Q0 906 625 G approximately €132.

That would also be another potential problem area, but without VCDS or VAS, you can only rule it out by (cross-)checking with another vehicle.

Hi,

Thank you for your answers.

Let's see if I'll have time to take measurements today.

I have VCDS - can I use it to test the N75 valve?

Best regards, David.

EDIT: The catalytic converter is fine - there are no issues with it.
It also doesn't rust much, or hardly at all.
I also assume that AhBeehTee has added a general +x% markup.
But the engine performs much better with the chip. Not just in terms of power, but more so in terms of driving characteristics.

Quote:

I have VCDS - can I use it to test the N75?

Please create a log for MWB 003 and 011, and specifically monitor the duty cycle in field 4 for MWB 011.

Rainer K. wrote:

Quote: However, I always have 130 mbar less ACTUAL boost pressure than EXPECTED boost pressure . This is somewhat unusual for 'normal' defects in the turbocharger. This should, if at all, only occur when the engine is extremely cold immediately after starting, when the turbocharger is not rotating.

Yes, but in my opinion, it definitely doesn't create a pressure of -130 mbar compared to the surroundings.
If you provoke it, for example, by disconnecting the VTG control hose, you will see almost no vacuum in an aspirated LDA at idle (in the range of up to ~30 mbar).
If you start driving (until the emergency mode kicks in), the LDA reading will decrease slightly towards -0.1 bar as the engine speed increases, but I've never seen it reach the full -100 mbar.
I suspect there's also an LD watering can modification being applied throughout the entire vehicle.

. . . It's amazing that, despite all this "extensive" customization, there's still enough profit left over to maintain the Allgäu glass palace .



EDIT

@davidshoes:
At what altitude did you conduct the tests that showed a 130 mb difference?
Simultaneously log data from MWB channels 10 and 11 while starting the engine. This should provide all the necessary information to solve the problem.

Okay, I've taken the measurements now:

For Ulf: MWB 10 and 11 during startup.

For VW enthusiasts, tools MWB 3 and 11.

Rainer Lehrlauftest: Full load at 1000-4000 min^-1 and 2000 min^-1 dynamically.

and then I just logged a regular trip.


I'm curious to see what happens. I suspect the problem lies in the chip and a combination of unfavorable factors like air pressure, temperature, and who knows what else.

Here's the translation:

"P.S.: The altitude is approximately 250 meters above sea level."

davidshoes wrote:

Okay, I've taken the measurements now: For Ulf: MWB 10 and 11 during startup

Nice:).
So, a target LD (line pressure) of almost 1100 mbar for a stationary engine is quite unusual.
Unfortunately, I don't have the original software for your engine. Based on my current understanding, it seems that the LD target value was increased using a "bucket" method.

Current status:

The vehicle is working better now, but it still occasionally malfunctions. The error seems to have resolved itself (instrument cluster, EDC).
It mainly occurs in damp conditions.

In the attached image, you can see the throttle valve and the EGR valve.
Below the pressure chamber of the AGR, there is oil.
The AGR pipe and cooler were recently replaced (due to a crack in the metal pipe).
The throttle valve (or swirl valve) is quite dirty, but I can't reach it to clean it. I probably need to remove the EGR cooler and the entire piping system in the back to get to it.
Unfortunately, due to time constraints, it was no longer possible to do any of those things.

Hi, there's nothing new to report yet, but something else occurred to me.

My father traveled 300 km over the weekend. For the first 20 km, he experienced the same symptoms again.

When I was recently inspecting the turbocharger system for leaks, I noticed that all the pipes were oily on the inside. When you tilt them, oil leaks out.

There was so much oil that a rag was completely soaked after I cleaned all the pipes.

I'm familiar with that from gasoline engines - the fuel can sometimes leak out strongly through the crankcase ventilation system.

Question: Is the oil normal?

It depends on how much it is... definitely no more than a tablespoon should come out of the tube.

Quote:

So, a target LD (Load Demand) of almost 1100 mbar for a stationary engine is quite unusual. Unfortunately, I don't have the original software for your engine. Based on my current understanding, it seems that the LD target value was increased arbitrarily.

I don't have the exact 1.4 TDI , but for example, the 019 BM has a target value of 1030 mBar in the low load range.

The 019 BR has a target pressure of 1018 mbar in the LL (Low Level) system.


I once tried it: using a watering can, I measured a meaningful value at full load, and it resulted in the aforementioned 1100 mBar in the LL (low load) condition .

I would say it was about 1.5 tablespoons...


I'll keep monitoring it.

Okay, some news.
My father drove a distance of 250 km on Friday.

In gears 4 and 5, it vibrates slightly at engine speeds of 1600-2000 RPM.

Otherwise, it runs perfectly - and the fuel consumption is also fine.

My guesses, in order:

* EGR valve leaking / clogged.
* The check valve in the intake manifold is stuck/clogged.
* VTG can leaking.
* Vacuum system leak, N75 valve defective.
* VTG mechanism jammed --> loader malfunction.

Unfortunately, I won't be able to get my hands on the vehicle until the end of February.
Then everything will be checked again, cleaned, and the seals will be replaced.

Can my father still drive the car for now?
imo is fine with that - what do you think?

Regards,
David.