2.0 TDI (CR) Engine Code CBAB - No Power + Soot Formation

Good morning,

I am new here and would like to start with a case study right away.

We have a 3C Passat, model year 2008 - engine code CBAB.

Customer Complaint:
No performance in the low-speed range.
Sometimes the Christmas lights flicker.

Error codes read out:
Download pressure limit threshold breached.

> VTG printing cylinder inspected.
> VTG printing canister is defective.
> VTG printing container replaced.

From now on, things will get weird:

If you gradually increase the throttle while stationary, the engine will run smoothly and all the values from the boost controller will be within the correct range.
If I give it full throttle while stationary, the engine speed will remain at approximately 2500-3000 revolutions per minute and the engine runs or "knocks" very harshly.
Sometimes he manages to go even further - one time, a cloud of smoke comes out of the exhaust and he revs the engine to its maximum.
If I give it gas until around 2000 RPM, briefly release the pedal, and immediately give it full gas again, it also revs up normally.

We suspect there is a problem with the VTG adjustment. Turbocharger removed and disassembled - everything is okay.

We have also repeatedly adjusted the pressure canister to the required values. (VCDS MWB 120) - No change.

- The particulate filter has already been burned out, as it had an extremely high differential pressure.
- The AGR valve was replaced because it was completely clogged with soot.
- The solenoid was temporarily replaced.


What is also striking is that the target values for the air masses are much higher than the actual values achieved.
The target/actual value for the charging pressure also does not match.

Addendum:
If you disconnect the vacuum hose from the VTG pressure gauge, the motor will normally start and run without stalling.

Please set full Auto Scan.

Here is the vehicle scan as requested.

Shame on my head
Now that I'm looking at the car scan.

Could it be the clutch position sensor...?
We only have the engine control unit data.

VTG failure = lots of soot. Load the particle filter accordingly.
You already wrote that he had a high differential pressure and that you had flushed him. But what is the differential pressure now?

MarcMS246 wrote:

Sometimes he even manages to go beyond that - one moment, a cloud of smoke comes out of the exhaust and he revs the engine to the maximum.

Strong soot from the exhaust should not actually get through the DPF. Perhaps it is already partially lodged and mistaken for soot in the exhaust system, etc. That would (just like a clogged DPF) explain the low air mass.

PS: However, a higher LM setpoint does not necessarily indicate a problem. It primarily means that the AGR should be completely off (as it is controlled by the LM). While the boost pressure LD also has an influence on the air mass LM, it is not regulated by it.

Greetings
Guste

Without problems with the fuel injection, engine control unit, or throttle position sensor, the engine speed cannot remain at 3000 RPM even with VTG (Variable Timing Gear) problems at idle.

Check the engine voltage at idle and the nozzles for leaks.

Experienced spontaneous ignition issues during idle and shifting (nailing and RPM fluctuations) due to excessively leaking injectors.

Greetings

Bo

The differential pressure is currently 21 mbar again.

The particulate filter was, however, sent out for cleaning.
Images from both the entrance and exit sides were satisfactory.

"The voltage at no load is also acceptable."
The return rate of the injectors was measured at idle - everything was also normal.

21 mbar at idle?
In my opinion, it's a bit higher than normal.

Yes, 21 mbar at idle.


But why does it spin out when I slowly increase the throttle in a normal way? Don't give it full throttle, just give it a quick burst.
If I disconnect the hose from the VTG, it still rotates normally, regardless of how much gas I give it.

MarcMS246 wrote:

Yes, 21 mbar at idle. But why does it spin out when I slowly increase the throttle in a normal way? Don't give it full throttle, just give it a quick burst. If I disconnect the hose from the VTG, it will also rotate normally, regardless of how much gas I give it.

Pump failure due to excessive back pressure in combination with VTG is possible, but then the speed only remains high for a very short time and does not stabilize. Na, that doesn't really help.

Greetings

Bo

Ste.Bo wrote:

Yes, 21 mbar at idle. MarcMS246 wrote: But why does it spin out when I slowly increase the throttle in a normal way? Don't give it full throttle, just give it a quick burst. If I disconnect the hose from the VTG, it will also rotate normally, regardless of how much gas I give it. Pump failure due to excessive back pressure in combination with VTG is possible, but then the speed only remains high for a very short time and does not stabilize. Na, that doesn't really help. Greetings Bo

Do not forget to check the oil level (overfilling). Also, check the function of the KGE, i.e., whether the oil filler cap remains loosely on the opening when the engine is idling or immediately falls off.

Is the motor control device software original? How did the error occur, from one day to the next, and when was it first noticed?

Best regards, Rainer

I will check the oil level again tomorrow morning. But since a colleague had already run the particle filter through the diagnostic tester before we sent it, he should have checked the oil level beforehand.

We checked the crankcase ventilation briefly today > The oil cap definitely needs to be in place. He's already starting to "dance" a bit.

According to our current knowledge, the engine control device software is original. (At least, that's what the customer says)

Unfortunately, we cannot say exactly when or how the error occurred. We don't know exactly how the engine was running before the faulty pressure canister was replaced.


I tried to perform a reset of the turbocharger (the VTG pressure sensor) again today.
However, he stops there. (Using both VCDS, BOSCH, and HELLA/GUTMANN) He starts with the basic setup, but is unable to achieve a signal voltage of approximately 0.9V. (The lower value was set to 0.760V according to specifications.)

MarcMS246 wrote:

I tried to perform a reset of the turbocharger (the VTG pressure sensor) again today. However, he stops there. (Using both VCDS, BOSCH, and HELLA/GUTMANN) He starts with the basic setup, but is unable to achieve a signal voltage of approximately 0.9V. (The lower value was set to 0.760V according to specifications.)

Likely, the VTG rod in the pressure container is incorrectly adjusted, be careful, risk of engine damage (if not already).

See:
/viewtopic.php?t=10810

Attention, do not adjust the settings according to your specific situation not. You have simply replaced the can.
During test drives always monitor the boost pressure trend and be prepared to ease off the accelerator before it overboosts and the turbocharger components are sucked in by the engine!

Best regards, Rainer

In a CR motor, it is perfectly normal that it does not rev up when stationary. Mine stops at 2500 min-1, regardless of which pedals I press. When it rolls, it can be raised.

Your MSG has experienced intermittent communication problems with multiple STGs (Brake, Air Conditioning, Central Electrical System, Switch Panel, Diagnostic Interface, Steering Assist, Parking Brake) after the log. However, it is working with their data. Even if it's just a sporadic error, the transmitted data doesn't necessarily have to be flawless.
I would like to delete these errors and see if they reappear. The central electrical system is also complaining about occasional undervoltage. Additionally, there is a problem with the clutch position sensor.
Before making any changes to the engine, perhaps it would be best to first get the electrical system under control?
hg
Herbert

dieselschrauber wrote:

Likely, the VTG rod in the pressure container is incorrectly adjusted, be careful, risk of engine damage (if not already). See: /viewtopic.php?t=10810

Later, be careful!

The CBAB has an inverted pressure vessel.
"It sucks" the pole out... the others suck in.

Okay, so that the arrows in the first image correspond to the aforementioned. Link not - they are different on CBAB !!!

Greetings
m;

Okay, we left for the weekend on time

Spoke with the customer and agreed that we will replace the turbocharger.

-> New turbocharger installed, basic turbocharger settings performed (worked without problems) and the car is running.
(We suspect that the replaced air filter housing might simply not "work well" with the turbocharger. "Although I managed to decipher the original message, I suspect something might still be wrong.)

Thank you for all the feedback!

Best regards
and a wonderful weekend!