SQ8 TDI Intake Issues Causing Power Loss & Jerking

I faced a very similar issue with my 2018 Q7 TDI. The symptoms match exactly what you described, poor performance, rough running, and that characteristic hissing sound during acceleration that points to intake system problems. After some engine misfires, I took it to my workshop where they diagnosed a defective switch intake manifold control. The airflow control system wasnt working properly, causing irregular air distribution. The repair involved replacing the intake manifold control unit and recalibrating the system, costing 465 Euro in total. The fix completely resolved the issues, power was restored, engine ran smooth again, and fuel consumption returned to normal. The entire repair took about 4 hours. Could you share: Current mileage on your SQ8? Any warning lights on the dashboard? When did you first notice the hissing sound? Have you had any recent maintenance work done? This information would help determine if your situation is similar and might need the same solution regarding the intake manifold system.

My car shows 119032 KM on the odometer and the engine has been regularly serviced, with the most recent maintenance completed just 2 months ago. The engine light started flickering last week, and the reduced power issue is particularly noticeable during highway merging. The hissing sound appeared gradually over the past month, becoming more pronounced during acceleration. Thanks for sharing your repair experience. The engine performance issues you described match my symptoms exactly. Sounds like I should have the air intake system checked, particularly the manifold control unit. Good to know the repair time and cost estimate, helps with planning the workshop visit.

Thanks for those details. Given your mileage and symptoms timeline, this definitely reinforces my initial suspicion about the intake manifold flap control system. When my Q7 hit similar mileage, the same progressive deterioration occurred. The flickering engine light is a key indicator, my car showed the same before the full diagnosis revealed the failing air intake components. The gradual onset of the hissing sound matches my experience too, it started subtle and got worse over a few weeks. Quick tip from my repair experience: have them check the entire air intake path while they are at it. In my case, they found some carbon buildup that was contributing to the engine performance issues. Getting that cleaned during the same service made a noticeable difference. Since your recent maintenance didnt catch this, the flap control issue likely developed afterward. The repair should restore proper engine performance and eliminate that hissing sound completely. At 119000 KM, this type of intake manifold issue is fairly common on these engines. The 465 Euro I mentioned earlier might vary slightly, but it should be in that range for parts and labor. The 4-hour repair time held true in my case, suggesting a straightforward fix once diagnosed.

Thank you for clarifying those symptoms and sharing your experience with a similar intake manifold flap issue. Based on the details about repair costs and timeframe, I will schedule a workshop appointment for next week. The fact that this happened to your Q7 at comparable mileage gives me confidence in the diagnosis. Your suggestion about checking the entire intake system makes sense, especially given my car has over 119000 KM. I will definitely ask them to inspect for carbon buildup while addressing the manifold flap control problem. The 465 Euro repair cost seems reasonable considering the complexity of the intake system work involved. The progression of symptoms matches exactly, from the initial hissing to the engine misfire and reduced power. Good to hear the fix completely resolved these issues in your case. I will update the forum once I get the repair completed to confirm if my air intake problems were indeed caused by the same manifold control unit failure.