VW Scirocco Diesel Power Loss Points to Worn Rings

Had similar issues with my 2015 VW Golf TDI. The symptoms you describe match what I experienced, poor performance, increased fuel consumption, and cylinder pressure problems. Initially suspected worn piston rings, but diagnostic testing revealed damaged fuel injectors caused by a failing turbocharger. The turbocharger issue led to improper fuel atomization, which then affected cylinder pressure and engine performance. The contaminated fuel spray had started damaging the piston rings as well. Key points to discuss with your mechanic: Request comprehensive turbocharger inspection, Have fuel injectors tested for spray pattern and timing, Check intake manifold for carbon buildup, Verify timing belt condition, as poor timing can affect cylinder pressure These components often have a chain reaction when failing. My repair required replacing the turbocharger, fuel injectors, and eventually the piston rings due to the damage progression. This was a serious repair requiring engine disassembly. When talking to mechanics, ask for all test results in writing and request they explain the relationship between failing components. A reputable shop will explain how one issue led to another rather than just listing parts to replace.

Thanks for that detailed breakdown. My Scirocco had similar symptoms last summer and the timing belt actually turned out to be the main culprit, though the intake manifold needed cleaning too. The engine ran much smoother after fixing both issues. What did your repairs end up costing? Did any other problems surface after getting the turbo and injectors sorted? Just wondering since my mechanic mentioned the crankshaft might need inspection soon, and I want to budget accordingly.

Since getting those initial repairs on my Golf TDI, the engine has performed perfectly with no engine knocking or other issues. The mechanic did a thorough job checking the entire system, including the crankshaft and camshaft, to prevent future problems. The original repairs were covered under an extended warranty since the turbocharger failure was traced back to a manufacturing defect. This meant the subsequent damage to injectors and piston rings was repaired at 0€. My case was unique though, normally this type of repair would be quite expensive. The cylinder pressure fluctuation you mentioned was exactly like mine and completely resolved after the repairs. The key was identifying that chain of component failures early. A proper diagnosis prevented what could have turned into major head gasket issues down the line. Based on your description, having the crankshaft inspected is a smart preventive measure. These engines are quite robust when maintained properly, but ignoring early warning signs can lead to costly repairs.

Thanks for the advice. I finally got this sorted out at a certified VW shop. The timing belt was showing early wear and the spark plugs needed replacement, both causing the sluggish performance. Total bill came to 850€ including parts and labor. The mechanic was really transparent, showing me the worn components and explaining how they affected engine performance. He also checked the crankshaft and camshaft while doing the work, both thankfully in good condition. Engine runs smooth now with no knocking sounds. Much better experience than my last sketchy repair job. The fuel consumption is back to normal and the check engine light has stayed off. Planning to stick with this shop for future maintenance since they seem honest and thorough.