SDI21.1 knock retardation

Hi guys,

I have 2020 Cayman T PDK (982/718), with SDI21.1 ECU. It is a 2.0 turbo boxer engine.

The car originally is equipped with OPF, which is removed from the car.

I had stage 1 tune and I was checking logs before I mount the hybrid turbo, but I noticed some difference in the ignition and inj opening time between cylinders.

It looks like ECU is adopting and retarding ignition and injecting less fuel.

I use 100-octane fuel in Europe. Tested with 100 + octane booster, the same. Tested with 100 + octane booster + 50/50 wmi, the same.

So, what I did is, replaced the spark plugs, and got no difference.

Tested compression, it's the same on all cyl.

Then I removed the injectors and tested them on ASNU maschine and cleaned them. There was a slight difference in volume in the long-term test, but just slight, and after cleaning and replacing some filters, it was the same on all injectors. After that, the log was also the same.

I asked Porsche to upload ECU and TCU tunes to the latest stock, and after resetting adaptations, it was making similar inj and ign but for a few runs until it starts adopting again.

I became furious, and I did decarbonization, and it was the same after that.

So, the Car is stock except OPF deleted.

The last thing I can do is to change both lambda sensors (waiting for them to arrive) and put OPF back to test.

Do you guys have experience, or at least some idea, of what is wrong there? :D

Here is my latest log: https://datazap.me/u/mladjan/after-decarbonisation?log=0&data=2-3-4-5-31

Why do you think it's wrong? Modern ECUs have all sorts of behaviors to optimize fuel economy.

I was looking at the log from another Cayman with the same engine, and he has the same ignition on all cylinders :\

Also, I see 3-4 degrees of knock retard on almost all cylinders.

These retards are maybe ok because stock ignition is high, on stage 1 tune I had less ignition advance and there were no retards (but higher boost pressure).

This is the log from stage 1 tune, and why I started investigating things: https://datazap.me/u/mladjan/new-plugs-and-coils-pure-petrol?log=0&data=1-11-12-13-14&zoom=108-247

Ignition was different between cylinders.

Then I logged with bflash to get info about the cyl number and details about injector opening time, and injector opening time matches reduced ignition:

https://datazap.me/u/mladjan/injectors-ignition-log2?log=0&data=20-21-22-23&zoom=892-1094

So, it is commanded from ECU.

Now with stock tune, ignition is still different a bit, but looks much better: https://datazap.me/u/mladjan/after-decarbonisation?log=0&data=14-16-17-21-31&zoom=809-984

But fuelling is weird: https://datazap.me/u/mladjan/after-decarbonisation?log=0&data=31-41-46-50-51-52-53&zoom=809-984

And lambda regulation factor between banks is weird to me: https://datazap.me/u/mladjan/after-decarbonisation?log=0&data=31-41-42-46-47&zoom=809-984