TDI: Insufficent Airflow at Full Throttle

Hello everyone,

Please help me.

The following situation exists: There is a slight deficiency in air mass at full load, approximately 80 mg/h.

It's not much, but I've done a lot of work on this engine, so I want to make sure everything functions correctly.

This year, the following items were renewed:

LMM (with the old one, there was a corresponding amount missing).
All 6 injectors.
DPF removed, welds opened, and cleaned with dry ice.
2 temperature sensors replaced.

The car is running normally.

No error codes.
Intake manifold and throttle valve removed, EGR valve removed, everything cleaned and checked.
The turbocharger air intake system has been pressure tested and is leak-free.

I've cleaned up the logs a bit; the part marked in red is my 'problem.'

Boost pressure, exhaust temperature, differential pressure - all within the expected range.
Everything is also fine at idle or under partial load.

Why is there a small gap between the 'IS' and 'SHOULD' values?

I would appreciate any suggestions or solutions.

Hi,

Do the swirl flaps open under load as well, and what about the differential pressure across the DPF under load?
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

Best regards, Rainer.

Camshafts thoroughly inspected?

Yes, the swirl flaps are opening, they have very little play, and according to the display, the actuators are working.

When I replaced the injectors, I visually inspected the camshafts and didn't see any signs of wear, nor could I feel any.

In my opinion, the differential pressure sensor is excellent. The sender and lines are also new.

Regardless of the gear and load, I'm not exceeding 230 mbar; before cleaning, it was over 300 mbar.


What else I've noticed is:

'If I unscrew the oil filler cap while the engine is running, nothing happens. There's neither noticeable vacuum nor pressure.'

Could the drain be clogged?

Oil consumption cannot be measured, and there are no signs of oil leaks.

Hi,

stop. I just reviewed your log, and you claim to have 80 mg/H of insufficient air mass.
I am 95% certain that your claim stems from a misunderstanding (misinterpretation of the logs), because only your actual air mass value is 80 mg/H below the target air mass value.

"Under full load conditions, as indicated by the recorded value, the EGR system is not active. Whether the actual value is higher or lower than the target value in this operating mode is, at best, dependent on the preferences of the application engineers."

If you therefore took everything apart and spent hours on it, that's a just punishment for not having purchased your VCDS from me after already finding help in this forum for over a year.

Because:
It's relevant to know if the air mass being drawn in under full load is too low, if the fuel injection quantity is being limited due to a misfire, or ideally, the current lambda value.
Do not include any comparisons between the desired and actual air mass values.

Okay:
The following measurements were recorded under full load:
- Force requirement for accelerator pedal (can also be specified as required torque in Nm). (1)
- Limiting quantity/moment via the transmission (2).
- Limitation of quantity/moment related to air mass/obscuration (3).

Then, in KDataScope, you should look at the three curves and as long as curve (3) is above curve (2), everything is fine.

Best regards, Rainer.