VW Transporter Power Loss & Engine Knock Symptoms Alert

Had similar issues on a VW Tiguan 2018 gasoline. The symptoms matched exactly, power loss, jerking, and smoke. Initially thought it was just a knock sensor, but diagnostic revealed carbon deposits in the combustion chamber causing detonation. The engine knock was happening because of pre-ignition, which left untreated can cause serious engine damage. The buildup was creating hot spots in the combustion chamber, leading to fuel igniting before the spark plug fired. The fix required: Cleaning carbon deposits, Replacing spark plugs, Testing fuel injectors, Adjusting fuel octane requirements, Resetting engine management system This repair was significant and required specialized equipment. The symptoms you describe strongly suggest similar combustion chamber deposits. Would recommend finding a shop with VW-specific diagnostic tools, as generic scanners might miss certain parameters. Important: Running the engine with severe knock can cause permanent damage to pistons and valves. Getting it checked soon is crucial.

Thanks for the detailed reply about the carbon deposit issue. Pretty sure I might be dealing with the same thing, especially since the piston slap and engine knock symptoms match exactly. The ignition timing problems you mentioned definitely sound familiar. Just wondering how much the total repair ended up costing you? Also curious if youve had any issues pop up since getting it fixed? Trying to budget for this and hoping to avoid any repeat problems with my Transporter. Really appreciate the warning about potential engine damage. Planning to take it in soon before it gets worse.

After seeing a specialist VW mechanic, the knocking combustion issue was completely resolved. The total repair cost came to 425€, which covered cleaning the combustion chamber deposits and related adjustments to restore proper engine tuning. Since the fix six months ago, the engine has run smoothly with no recurring problems. The cylinder heads are in good condition now, and the ignition timing is properly calibrated. The knock sensor readings are normal, showing the combustion is happening exactly when it should. The repair was worth every cent considering how much damage could have occurred if left untreated. The engine performance is back to factory specs, with no more power loss or exhaust smoke issues. Would definitely recommend getting yours checked soon to prevent any serious engine damage.

Thanks for the advice. I took my Transporter to a certified VW workshop last week and turns out it was exactly what was described, carbon buildup causing detonation issues. The knock sensor was picking up the problem correctly. The mechanic did a full combustion chamber cleaning, replaced the spark plugs, and recalibrated the ignition timing. Total bill came to 390€ which seems fair compared to what others paid. They showed me the carbon deposits they cleaned out, it was pretty bad. The difference in performance is like night and day. No more engine knock or jerking during acceleration. The exhaust is clean now and power delivery is smooth again. Really glad I caught this before it caused permanent damage to the cylinder heads. Will definitely keep an eye on fuel octane ratings going forward and stick to the recommended maintenance schedule. Lesson learned about not ignoring those early warning signs.