VW Lupo Engine Misfires, Rough Running & Power Loss

Having experienced similar symptoms on my VW Polo (2003, 1.4L gasoline), this sounds like a typical injector issue. The rough idle, power loss and combustion misfire match what I encountered. The throttle response problems turned out to be caused by a faulty fuel injector. The diagnosis process included checking fuel pressure and running injector tests. The mechanic found one injector was not spraying properly, leading to incomplete combustion. This explained the check engine light and jerking sensation during acceleration. The repair required replacing two fuel injectors and cleaning the remaining ones. This was a serious repair that needed immediate attention, as bad injectors can cause additional engine damage if left unchecked. Key indicators that point to injector problems: Rough idle that gets worse over time, Inconsistent throttle response, Clear combustion misfire symptoms, Drop in power, especially during acceleration Before replacing parts, have a proper diagnostic scan done. Sometimes similar symptoms can be caused by failing ignition coils or a weak fuel pump, but the pattern you describe strongly suggests injector problems. Consider having all injectors tested, as they often wear at similar rates. This prevents having to repeat the repair soon after.

Thanks for sharing your experience with the injector issues. That sounds exactly like what my Lupo is going through right now. The cylinder misfire and engine misfiring symptoms are identical. Just wondering, what did the repair end up costing you? And have any spark plug or injector problems come back since the fix? I want to budget properly and make sure I fix it right the first time to avoid repeat issues.

Good news, got the Lupo fixed and the combustion misfires are completely gone now. Had one defective fuel injector replaced for 515€, which included parts and labor. The mechanic ran a full diagnostic test afterward to confirm the engine misfiring was resolved. Since the repair three months ago, the car runs perfectly smooth with no return of the rough idle or power loss issues. This confirms the fuel injector was definitely the root cause. Neither the spark plugs nor the other injectors have shown any problems since then. For reference, the repair shop pressure-tested all injectors and found only one was faulty, so replacing just the problematic one was sufficient. They also inspected the ignition coils and fuel delivery system as a precaution, but everything else checked out fine. The improvement in performance and smooth acceleration was immediately noticeable after the repair. When dealing with misfire symptoms, investing in proper diagnostics and quality parts really pays off in the long run.

Thanks everyone for the detailed advice. I took my Lupo to a certified mechanic last week. After running diagnostics, they confirmed a faulty fuel injector was causing the combustion misfire. The total repair came to 490€, which included replacing one bad injector and cleaning the others. The check engine light is now off and the car runs perfectly, no more jerking or power loss during acceleration. The mechanic also inspected the spark plugs and fuel pump while they had everything apart, but those components were still in good shape. Really glad I addressed this quickly before it could cause more engine damage. The improvement in performance was instant and dramatic. Lesson learned about not putting off repairs when misfire symptoms first appear. Thanks again for helping me diagnose this correctly. Would have wasted time and money checking other things first without the guidance here.