Stelvio Engine Knock Causes Power Loss and Smoke

I had a similar issue with my 2017 Giulia, the symptoms you describe match exactly what I experienced. As someone with moderate experience working on cars, I learned quite a bit dealing with this problem. The engine knock and power loss turned out to be caused by carbon deposits in the combustion chamber. Poor fuel octane and incorrect ignition timing made it worse over time. The workshop did a thorough cleaning of the combustion chamber and adjusted the timing, which resolved the detonation issues completely. Total cost was 425 Euro including diagnostics. Before committing to repairs, could you share: Current mileage, Type of fuel youve been using, Whether youve noticed the issue getting worse in hot weather, Any recent changes in driving patterns These details would help determine if youre facing the same root cause. Its important to address this quickly, as continued engine knock can lead to serious damage. The knock sensor should normally prevent major issues, but its worth getting it checked professionally. The smoke you mentioned could indicate a related but separate issue, worth investigating if its blue or black smoke.

Last serviced at 137665 KM and the knock sensor diagnostic confirmed my suspicions. The repair shop found the ignition timing was out of spec, leading to pre-ignition and engine knock. They recalibrated the system and replaced a faulty knock sensor which had failed to detect the detonation early enough. The fix included cleaning carbon deposits and adjusting fuel injection timing. Total repair cost was 680 Euro. Running much smoother now with no power loss or smoke. Been using higher octane fuel since to prevent future issues. I recommend getting it checked soon to avoid potential engine damage.

Thanks for the update on your Stelvio repair. Had almost identical issues with my 2019 model, the knock sensor failure combined with carbon buildup created quite a mess in the combustion chamber. Pre-ignition and detonation problems can really snowball if left unchecked. Your repair costs seem reasonable considering the work done. The cleaning and recalibration made a huge difference in my case too. Been running mine for about 15000km since the fix with zero engine knock issues. Switching to higher octane fuel definitely helps prevent these problems from recurring. One tip, I noticed keeping the RPMs moderate during warm-up helps minimize carbon deposits. Also worth checking the knock sensor readings periodically through an OBD scanner to catch any early warning signs of piston slap or abnormal combustion. Good to hear yours is running smoothly again. These engines are solid when properly maintained, just sensitive to ignition timing and fuel quality issues.

Thanks for following up on my issue. The cylinder heads were inspected during the repair and showed minimal wear despite the knock sensor failure. The mechanic confirmed the ignition timing adjustment and carbon cleaning resolved the pre-ignition completely. No signs of piston slap or combustion chamber damage, thankfully. Great tip about monitoring RPMs during warm-up. Ive been paying closer attention to that and using premium fuel exclusively now. The engine feels much more responsive since the repair, especially under load. No more smoke or power loss issues. The 680 Euro investment was worth it to prevent more serious engine damage. Will definitely keep an eye on the knock sensor readings going forward. Really appreciate all the helpful feedback from everyone who shared similar experiences. Gives me confidence the problem is properly resolved.