Audi Q8 TFSI Timing Issues Causing Power Loss

I had a similar issue with my 2019 Audi Q7 3.0 TFSI last year. The symptoms match exactly what you describe, check engine light, increased fuel consumption, and noticeable power loss. Having some experience with variable timing systems, I suspected a VANOS solenoid problem from the start. The workshop confirmed a defective camshaft solenoid valve was causing the engine misfire and low power issues. The total repair cost was 250 Euro, covering parts and labor. The repair process was straightforward, they replaced the faulty solenoid valve and cleared the error codes. After the fix, fuel consumption returned to normal and the power delivery was smooth again. Before suggesting specific solutions, could you share: Any error codes from an OBD scan? Does the power loss occur more at specific RPM ranges? Have you noticed any unusual engine sounds? When was your last oil change? This information would help determine if your issue is identical to what I experienced with my Q7.

Thanks for the previous replies. I managed to have the car scanned at a local shop and got error code P0016. The engine misfire seems more noticeable at lower RPMs, especially when cold. Latest oil change was at 98000 KM, using fully synthetic oil as specified by Audi. It turned out oil sludge had accumulated in the VANOS solenoid, causing the variable timing system to malfunction. Regular oil changes probably could have prevented this buildup. The shop found small metallic particles when they removed the old VANOS solenoid, suggesting internal wear in the timing system. Would be helpful to know if anyone else had similar findings with their Q8s and what preventive measures they took afterward.

Thanks for the update. Yes, your findings with the P0016 code and oil sludge match my experience perfectly. After my initial VANOS solenoid replacement, I also discovered metallic debris during the repair, which prompted a more thorough investigation of the variable timing system. To prevent future VANOS failure, I implemented these changes: Shortened oil change intervals to 7500 KM, Switched to a higher-grade synthetic oil with better cleaning properties, Added an engine flush during every other oil change, Monitor oil pressure more frequently using an OBD reader These steps have kept my Q7 running smoothly for 25000 KM since the repair, with no check engine light or power issues. The extra maintenance cost is minimal compared to another major VANOS repair. The metallic particles you mentioned are concerning. Make sure your shop thoroughly cleans the oil passages and checks the camshaft wear. In my case, addressing the issue early prevented more extensive engine damage.

Thanks for all the helpful replies. Those P0016 codes definitely pointed to timing chain and VANOS issues. After getting the initial repair done with the solenoid replacement and oil system cleaning, I made some changes to prevent future problems: Started using premium synthetic oil rated specifically for inlet camshaft and variable timing systems. Also switched to 5000 KM oil change intervals for now, at least until I'm confident the VANOS system is running clean. The shop did a thorough inspection of the timing chain components while they had things apart. Found minimal wear thankfully, so catching it early saved me from bigger problems. The metallic debris turned out to be from normal wear rather than component failure. Since the repair, fuel economy is back to normal and power delivery is smooth across all RPMs. Will keep monitoring with regular OBD scans to catch any VANOS solenoid issues early. Appreciate all the maintenance tips, they'll help prevent future variable timing problems.