VW Scirocco Power Loss + Smoke Points to Fuel System Fix

Had similar symptoms on a 2014 VW Golf GTI. The main issue was indeed fuel injection related, faulty fuel injector wiring harness caused irregular fuel delivery and engine power loss. The maintenance involved testing the injection system pressure and inspecting all electrical connections. Found corroded wiring near the engine harness connector, which caused intermittent signal issues to the injectors. The erratic fuel delivery explained both the excessive fuel consumption and smoke under load. This turned out to be a serious repair requiring specialized diagnostic equipment to properly identify. The complete job included replacing the wiring harness and testing all injector connections. Also needed to clear the engine management system to reset learned values. The symptoms match perfectly, unstable idle, power loss, and increased petrol usage are classic signs of injection system electrical faults. Proper diagnosis is crucial since these symptoms can also indicate worn injectors or fuel pump issues. Would strongly suggest finding a shop with VW-specific diagnostic equipment for accurate troubleshooting.

Thanks for sharing your experience. That wiring harness issue sounds exactly like what I dealt with on my Scirocco last winter. Engine performance was terrible until I got it fixed. Did the smoke problem completely go away after the repair? And mind sharing what the final cost was for the harness replacement and diagnostic work? Just wondering if prices have changed much since then. My mechanic is quoting higher than I expected for similar work.

The smoke issue cleared up completely after fixing the injection system fault. What looked like a major problem turned out to be just a loose connection in the wiring, much simpler than the full harness replacement I initially feared. The performance returned to normal right after the repair. The total cost came to 95€, which covered diagnostic work and fixing the faulty cable connection. This seems reasonable compared to a complete harness replacement, which would have been much more expensive. If your mechanic is quoting significantly higher prices, they might be assuming worst-case scenario repairs. Regular maintenance checks could have caught this earlier, but these electrical issues can develop suddenly due to engine vibration and heat. The air around the engine compartment can get quite hot, which sometimes affects wiring connections over time. Since the repair, fuel consumption returned to normal and the engine maintains steady power without any performance issues. No more smoke under acceleration either. Definitely worth getting a proper diagnosis to avoid replacing parts unnecessarily.

Finally got the Scirocco sorted at a different garage last week. Turned out you were spot on about the injection system. The mechanic found damaged wiring near the fuel rail that was causing all sorts of issues. The maintenance bill came to 180€ including diagnostics and repair work, bit more than yours but still better than a full harness replacement. The performance difference is incredible. No more black smoke under acceleration and fuel consumption has dropped back to normal levels. Engine runs smooth at idle now too. Really glad I got a second opinion instead of going with my regular shop who wanted to replace the entire injection system. Pretty relieved it was just an electrical issue causing the poor performance rather than something more serious. The new mechanic showed me the corroded wiring, definitely something regular inspections should catch before it gets bad.