Q8 Diesel Rough Running: Drift Comp Issues & Solutions

As an A6 2016 diesel owner, I encountered similar symptoms last season. The onboard diagnostics showed drift compensation issues pointing to a faulty fuel injection system. The rough running was caused by a defective injector that wasnt delivering the correct fuel amount. The repair required removing and testing all injectors. One had failed completely, causing uneven fuel distribution and poor fuel economy. The process involved: 1. Complete injector diagnostics 2. Removal of faulty injector 3. Installation of new injector 4. Performance tuning and reset procedure for the engine control unit 5. Test drive to confirm proper operation This was a serious repair that required specialized equipment and expertise. The car ran noticeably smoother after fixing, and fuel consumption returned to normal. The check engine light cleared after the repair shop completed the reset procedure. Your symptoms match exactly what I experienced. Given the age and mileage of your Q8, its worth having all injectors tested. Leaving it unfixed risks further engine damage and continued poor performance. The repair took about 6 hours at the shop, and they needed to order the parts. Consider asking for a full injection system inspection while they have it apart.

Thanks for sharing your experience with the injector repair. That sounds very similar to my issues. Mine turned out to be a drift compensation problem caused by faulty airflow sensors and injector timing. The rough running cleared up after the fix. Did you notice any other issues pop up since the repair? Also, curious about the total cost you paid, would help me budget for my upcoming shop visit.

Good to hear your drift compensation issues were resolved. After my initial repair visit, I can confirm the injection system has been running flawlessly for months now. The complete reset of the quantity drift compensation solved the rough running problem permanently. The total repair cost came to 515 Euro for replacing the defective injection valve. This included the specialized diagnostic work, parts, and labor. The performance tuning after installation was critical to ensure everything worked correctly with the engine control unit. Since the fix, the engine has been running smoothly with no warning lights or performance issues. The onboard diagnostics show normal readings, and fuel consumption has stayed consistent. Just make sure your shop properly resets all parameters after the repair, this is crucial for optimal performance. My advice would be to have them check the airflow sensors while they're at it, as these can also affect engine performance and sometimes fail around the same time as injector issues.

I visited my mechanic last week and Im relieved the problem is finally fixed. The car sensors detected the same drift compensation issue that matched your experience. The repair shop found the main problem was with both the airflow sensors and fuel injection system. The total repair came to 490 Euro. The mechanic spent about 4 hours doing: Full diagnostic scan, Airflow sensor replacement, Fuel injector cleaning and timing adjustment, System reset and calibration The engine runs perfectly smooth now. No more check engine light and the rough running is completely gone. The onboard diagnostics show everything is back to normal ranges. Really appreciate the detailed info you shared, it helped me know what to expect and gave me confidence to get it properly fixed this time. The repair cost was actually less than I feared after seeing your numbers.