Envision Stalling: Fuel System Diagnosis Needed

Having experienced similar symptoms with a 2016 Buick Enclave, I can relate to this fuel system concern. When my engine had stalling issues at idle, it turned out the fuel mixture was running too lean due to a faulty mass airflow sensor connector. The check engine light was triggered by this incorrect fuel-air mixture. The root cause was a corroded electrical connection at the sensor plug. What appeared initially as a minor issue could have led to serious engine knock problems if left unaddressed. After properly cleaning the connection points and securing the plug, the stalling issue resolved completely. Given your symptoms, poor fuel economy and stalling, it would be worth checking both the fuel system and electrical connections to your engine sensors. A clogged fuel filter or fuel contamination could also cause similar symptoms. The repair itself was straightforward once properly diagnosed. Before replacing parts, have a professional check the electrical connections and run a proper diagnostic test. The symptoms you describe are potentially serious if left unattended, as they can lead to catalytic converter damage or worse engine problems over time.

Thanks for sharing your experience with the mass airflow sensor. My fuel system issues were finally resolved last month, but I am curious about your repair costs. Mine was rather steep since I waited too long and had developed some fuel contamination issues that required a thorough system cleaning. Would you mind sharing what you paid for the diagnosis and repair? Also, have you noticed any recurring problems since getting it fixed? I am asking because my Envision occasionally still feels a bit rough at startup, though the stalling is completely gone. Want to make sure I am not missing any warning signs of potential issues.

After getting the wrong fuel mixture issue fixed by addressing the faulty sensor connection, my total repair cost came to 95€. This mainly covered the diagnostic work and fixing the cable connection that was causing the problem. Much more affordable than a full fuel system cleaning or sensor replacement. The rough startup you mentioned caught my attention, while I had zero issues after my repair, this could indicate the fuel filter might need attention. My mechanic explained that even after fixing the main fuel system problem, residual contamination can sometimes affect cold starts. Since the major work has been done on your vehicle, monitoring your fuel economy would be a good indicator if any new issues develop. In my case, fuel efficiency returned to normal immediately after the repair and has stayed consistent for the past year. If the rough startup continues, it might be worth having the fuel filter checked as a preventive measure. It is a relatively simple inspection that could prevent more serious fuel system problems down the road.

Thanks for the helpful information everyone. I wanted to share how my situation finally got resolved. After getting recommendations from several forum members, I found a certified shop that specializes in fuel system diagnostics. The mechanic first ran a complete fuel system analysis and found significant buildup in the combustion chamber along with a partially clogged fuel filter. The total repair included cleaning the entire fuel system, replacing the fuel filter, and adding fuel additives to help prevent future deposits. While it cost more than I initially hoped (around 400), the difference in performance was immediately noticeable. The idle is now smooth, my fuel economy has improved significantly, and the check engine light has stayed off. My only regret is not addressing the issue sooner before the fuel contamination became more severe. The mechanic explained that regular maintenance could have prevented most of the buildup. At least now I know what warning signs to watch for and the importance of not delaying repairs when fuel system issues first appear. Would definitely recommend getting any similar symptoms checked out early rather than waiting like I did. The peace of mind from having it properly fixed is worth the investment.