Jerking and hesitation with Polo 1.2 TDI (2013), only between 1500–2000 RPM

Hello everyone,

I’m facing a jerking/hesitation issue on my Polo 1.2 TDI, mainly between 1500–2000 RPM.

I got all 3 injectors bench tested and found that one injector had 3 faults. That injector was serviced, retested, and passed without errors.

After reinstalling everything, the car feels slightly better, but the jerking is still there.

A few more details:

• The issue is worse when the engine is cold
• It usually reduces a lot or disappears after around 30–45 minutes of driving
• If I accelerate hard in 2nd or 3rd gear, I can still see some black smoke
• The car has done around 95,000 km
• No check engine light or fault codes

My question is: after injector servicing, should I get injector adaptation/coding done, or will the ECU automatically micro-adjust over time?

Would really appreciate input from anyone who has dealt with this on the 1.2 TDI 3-cylinder.