Pinging noise and hot engine 1.4 BBZ

[Crt_cc]

Hello everyone, I need help on a VW Polo 9N3 1.4 BBZ.
The engine suffers from severe spark knock/pinging under load (around 2000 RPM) and runs excessively hot.

Here is the live data from OBD (Car Scanner):
• Long Term Fuel Trim: -23.4% at idle.
• Short Term Fuel Trim: -6% at idle.
• Engine Coolant Temp: 95°C cruising at 60 km/h, climbing up to 104°C in city traffic.
• MAP Sensor: Reads normal, 36 kPa at idle.

The radiator fan 1st stage seems not work, it only kicks in at 103°C. I have already replaced λ sensor, radiator, water pump, and thermostat twice. The throttle body has been cleaned.
What could be forcing to pull 23.4% of fuel, lean condition and knocking under load? Could a wrong fuel filter or a faulty EVAP/EGR valve? Any insights on what is the problem would be highly appreciated!

[iichel]

With LTFT at -23%, the ECU is pulling fuel, so the data points to a rich condition or the ECU being fooled into thinking it is rich, not a lean condition.

If it has been running rich for a while, carbon/soot build-up on the piston crowns and combustion chambers is possible. That can create hot spots and contribute to pinging under load. But I would treat that as a consequence, not the root cause.

Pull the spark plugs and inspect them. If all plugs are black/sooty, look for a global rich cause such as excessive fuel pressure, wrong fuel filter/regulator, coolant temp sensor, MAP/IAT issue, or EVAP purge stuck open. If only one plug is black, suspect an injector on that cylinder.

I would verify fuel pressure first, especially if the fuel filter/regulator may be wrong.