RSQ3 Engine Stalls & Power Loss Due to Fuel System Issues

Had a similar situation with my RS4 2017 last year. The symptoms match exactly what I experienced, stalling at idle, drop in power, and persistent check engine light. Initial diagnosis pointed to the fuel pressure regulator, but after thorough testing, the actual problem was more complex. The fuel rail pressure drop was significant during idle, caused by a failing fuel pump. The problem started shortly after a routine fuel filter change. The new filter revealed the underlying weakness in the pump system that wasnt noticeable before. The repair required: Complete fuel pump replacement, New fuel pressure sensors, System diagnostic reset The issue was serious as continuing to drive with low fuel pressure could have damaged the fuel injectors and catalyst converter. Getting it fixed promptly helped avoid more extensive engine damage. This is a known fuel efficiency issue with this engine series. When the pump starts failing, it creates irregular pressure in the fuel rail, leading to the symptoms you describe. Would strongly suggest getting a proper diagnostic test done with a focus on fuel delivery system pressure readings. The check engine light in these cases usually stores specific fault codes related to fuel rail pressure, which helps narrow down the real problem.

Thanks for sharing your RS4 experience. That really helps as the symptoms match what my RSQ3 is doing. Quick question, do you remember roughly what you paid for the complete repair? Also wondering if youve had any similar issues pop up since getting it fixed? The fuel pressure sensors and pump replacement seem like the logical fix, just trying to budget for what might be coming.

After fixing everything on my RS4, I can say it was worth every cent. The engine misfire and stalling issues completely disappeared once the fuel pressure regulator was replaced. My total repair costs were much higher than yours will likely be since I needed the full pump replacement. In your case, since the mechanic found the actual issue was just the fuel pressure regulator being defective, you got lucky. The 45 Euro diagnostic fee to clear the check engine light after the fuel filter change seems reasonable. Havent experienced any fuel system problems in the 14 months since the repair. The car runs perfectly at idle now, and the check engine light hasnt returned. Fuel efficiency actually improved slightly after the fix. A tip for future reference, keeping detailed service records of fuel system repairs helps track if similar issues return. But based on my experience, once the pressure regulator is properly fixed, the problem stays solved.

Just got back from the mechanic who properly diagnosed my RSQ3. Turns out the fuel pressure regulator was indeed the problem, causing the engine misfires and stalling. The complete repair including parts and labor came to 850 Euro. The mechanic showed me the diagnostic readings from the fuel rail pressure sensor that clearly indicated irregular pressure drops. They replaced both the regulator and installed a new pressure sensor as a precaution. Been driving for a week now and the engine runs perfectly, no more stalling at idle or power loss. The check engine light has stayed off and fuel consumption seems better than before. Really glad I got a second opinion and proper diagnosis. The total cost was lower than I expected considering the potential for more extensive fuel system damage if left unfixed.