TDI 2.5: Compression Problems & Solutions

Hello,

I'm having the following problem. The compression in my V6 TDI AKN engine is distributed as follows (from cylinder 1 to 6): 27-29-31-31-32-31. When the engine is cold, this causes rough running, and the engine smokes excessively. I noticed the compression loss in mid-November and subsequently removed the cylinder head. The valves for cylinders 1-3 were re-ground, as cylinders 1 and 2 were leaking, and the hydraulic lifters were replaced. After that, the problem was gone, and the full power was restored. . The compression was above 30 on all cylinders. Now, I've noticed over the past 4 weeks that the problem is gradually reappearing. Today, I checked the compression again, and I see that cylinder 1 has 28, and cylinder 2 has 29. Can anyone help me understand what else this could be?

Best regards,
Sure, here is the translation of the text from German to English:

"Au00"

Well, the target compaction value is between 27-33 bar...
Everything is still going well!


Otherwise, it could be the piston rings, the head gasket might be damaged again, or the valves might not be closing completely.

The compression is actually already in the foundational area.

Take a look at the idle speed control. It often indicates a faulty fuel injector.
If it's defective, it can cause jerking throughout the entire speed range. It's also possible to have an uneven idle speed even when the engine is idling. }

Thank you for the response. I plan to replace the rocker arms for cylinders 1-3 soon, and possibly the camshafts (they already show signs of wear).