2.0 TSI ignition timing temporarily negative during acceleration

Good evening, diesel mechanics.

I've noticed that the ignition timing is being significantly retarded during acceleration in my Golf 6 GTI with the CCZB engine. In the area where the ignition timing is negative, a noticeable drop in performance is observed.
So far, I haven't found anything that could trigger this ignition timing retardation.
The engine had already been repaired due to high oil consumption. During the repair, the pistons, intake and exhaust valves, injectors, and turbocharger were replaced. The camshafts were inspected and are in good condition, and the camshaft timing is functioning correctly, as confirmed by the target and actual values in VCDS. Similarly, the values for rail pressure and boost pressure are also correct.

Do you have any idea where this might be coming from, and how we can best narrow it down?
In the attached log, you can clearly see that the ignition timing is being retarded, but the knock control system is not responsible for it.

This performance issue was already present before the engine overhaul, and it occurs with both the standard tuning and with performance upgrades, although it is more pronounced with the latter.

I would be very grateful for any help, as this has been troubling me for a very long time.

Greetings and have a lovely Sunday.

Hannes.

Hi,

What kind of fuel do you use? Is there a measurement block available for knock sensors?

Best regards, Rainer.

Evening, Rainer,
Right now, there's Aral Ultimate in the tank. It's slightly more powerful when using Super 95.
What values from the knock sensors would be interesting? The values for the ignition timing retard of the knock control system can be found in the MWB 20, in the log.
Greetings.
Hannes.

Hello,

Regardless of any performance issues, it would be interesting to compare the results with the standard data set when the ignition timing is adjusted. "It seems some strange values have crept into the relevant data fields..."

Have you checked the intake air temperature and the correction factors for the lambda control (the engine may be running too lean because the injectors are clogged or the fuel pressure is insufficient)?

What is the behavior of spark timing retard and lambda control at high RPM and full load?

Best regards, Rainer.

Hi,
I'll flash the original dataset onto it this afternoon. It looked similar to a timing retard, but I don't have any proper logs to confirm that.

The charge air temperature, depending on the engine load and when the engine is warm, is between 2° and approximately 15° above the ambient temperature. Under load, the temperature rises relatively quickly to a few degrees above the ambient temperature.

The lambda values seem to indicate a mixture that is too rich. The correction values at idle are currently at -1.5, and the value for partial load is between -3.5 and -4. The real-time values are also tending towards the negative range. With chip tuning and the original data set, these values are in the same range.

The injectors were replaced during the engine repair, which is what I suspected. Unfortunately, without success.

I've been told that the lambda values could be affected by a clogged catalytic converter. The pressure side of the turbocharger, from the turbocharger to the engine, and from the air filter to the turbocharger, are sealed. The crankcase ventilation system also maintains the boost pressure.

I will run the full-load tests today or tomorrow. Should I drive one car with the chip tuning and one without, for comparison?

Greetings.

Hannes.

Good evening.

Here is the full-throttle log with the standard dataset. There was only about a 10-minute gap between the flashing and the driving, so the engine control unit was not yet able to collect any learning values.

Have a good evening.

Greetings.

Hannes.

Hi.

"The possibility of a serial error has already been ruled out." Please consider the air mass and ensure a good sampling rate.
Someone might have comparable data for a similar engine.

Best regards, Rainer.

Hi,

What other values, besides air mass, should be visible?
For a sampling rate of 7 samples per second, I can log two data streams. Is that enough, or should I just try driving one where the focus is primarily on the air mass?

Greetings.

Hannes.

Here's a full-throttle log in 4th gear, showing air mass and ignition timing from the engine control unit (ECU), and another full-throttle log in 4th gear. Walk with the MWB 1 and MWB 3.

Hi.

I only observe a noticeable reduction in ignition timing below 2500 rpm. The maximum air mass is approximately 180g/s, which is roughly equivalent to...
Okay, I'm ready. Please provide the German text you want me to translate.
it can be estimated to have a power output of 163 kW, which is approximately 222 horsepower.

Best regards, Rainer.

Hi Rainer,

The range below 2500 RPM is also where I notice it.
Do you have any idea what might be causing this? If it turns out, as I've been told, that the issue is related to the catalytic converter (I'm not sure if that's the case), can I check it without having to use a separate connection on the downpipe to measure the exhaust pressure?

Greetings.

Hannes.

According to Google, the CCZB engine has approximately 210 horsepower. Therefore, the airflow rate required for 222 horsepower is a good fit, and a blockage is unlikely.

Best regards, Rainer.

Okay, that's good, at least I can rule out the cat.
The question remains: why is the ignition timing being retarded so significantly that it affects driving performance?
What would you check first in this situation, if you didn't know what had already been done to the engine?

Greetings.

Hannes.

I would first compare it to other engines of the same type and then decide whether it is abnormal or not.
Best regards, Rainer.

The EA888 engine has an adjuster for the intake camshaft that is rotated by oil pressure. In VCDS, there is a measurement block that displays the target and actual values for the camshaft adjuster. Do you know if it's possible to tell from the values whether the adjuster is working correctly?

I went back to the workshop again because of the shaking/sagging issue. Unfortunately, so far, everyone is at a loss as to where it could be coming from.
Is there anyone nearby Bielefeld who is knowledgeable about engines, or knows someone who is?

Greetings.

Hannes.

Hello.
Is there a basic setting on my engine that allows me to disable the lambda control (oxygen sensor)? It's listed in the dropdown menu in the basic settings of VCDS, but it doesn't work.
It just says that it's not available.
Greetings.
Hannes.