VW Virtus TSI Engine Knock Causes Power Loss & Smoke

I had a very similar issue with my 2017 VW Polo 1.0 TSI about 6 months ago. As someone with some experience working on engines, I initially thought it was related to ignition timing, but it turned out to be more complex. The symptoms matched yours exactly, reduced power, jerking during acceleration, and engine knock that got worse over time. The main culprit was carbon deposits in the combustion chamber, which led to pre-ignition issues. The workshop did a thorough cylinder heads inspection and found significant buildup affecting combustion efficiency. The fix involved: Complete cleaning of combustion chambers, Adjustment of ignition timing, New spark plugs, Engine tuning to optimize performance Total cost was 425€ and took about 2 days to complete. The car has run perfectly since then. Before I can provide more specific advice, could you share: What fuel grade do you typically use? How many kilometers on the engine? When was your last spark plug change? Any recent engine tuning or modifications? This information would help determine if your issue matches what I experienced and whether you might need similar repairs.

Latest service was at 90000km, just 2 months ago. Your description matches exactly what happened just after I switched to a different fuel station. The piston slap noise became noticeable within days. My mechanic also found carbon deposits affecting the combustion chamber performance. The repair involved cleaning the cylinder heads and adjusting ignition timing to factory specs. Total repair cost was 380€ including diagnostic and labor. They also recommended using higher octane fuel to prevent pre-ignition issues in the future. Running much smoother now and power delivery is back to normal. Regular maintenance and quality fuel really make a difference in these TSI engines.

Good to hear your repair went smoothly and cost less than mine. The connection between fuel quality and carbon deposits is often overlooked, but it can seriously impact engine performance. The piston slap you mentioned is a classic symptom when deposits build up and affect proper combustion. After my repair, I also made some changes to prevent future issues: Switched to premium fuel exclusively, Added fuel system cleaner every 15000km, Monitor for any early knock sensor warnings These TSI engines are quite sensitive to ignition timing and fuel quality. When the knock sensor detects detonation, the ECU reduces power to protect the engine, which explains the performance loss we both experienced. Have you noticed any difference in fuel consumption since the repair? My efficiency improved noticeably after getting the carbon cleaned and timing adjusted. Also worth mentioning that my mechanic suggested shorter oil change intervals can help prevent deposit buildup. Just keep an ear out for any unusual sounds during acceleration. Early detection of engine knock can prevent more serious damage down the line.

Thanks for sharing details about your fuel station switch causing the issue. The piston slap noise appearing so quickly after changing fuel sources really highlights how sensitive these TSI engines are to fuel quality. My mechanic did exactly the same repairs, cleaning the cylinder heads and resetting timing. Getting similar repair costs around 380€ is reassuring since I was worried about potential overcharging. The higher octane fuel recommendation makes sense to prevent pre-ignition problems. You're absolutely right about the importance of maintenance and fuel quality. After the repair, I'm being much more selective about where I fuel up. The engine response is so much better now, no more hesitation or power loss during acceleration. The knock sensor readings have stayed normal and I haven't heard any concerning sounds. Think I'll stick to the premium fuel going forward. These small turbocharged engines need the good stuff to prevent detonation issues. Really glad I caught the problem early before it caused more extensive damage to the combustion chamber components.