Rough Cold Start in Buick GL6 Despite Clean Injectors

Had the same symptoms with a 2016 Buick Envision. The hard starting and rough idle during cold mornings pointed to a faulty fuel injector. After multiple attempts at fuel system cleaning, the diagnostic revealed a bad injector causing inconsistent fuel delivery. The injector test showed one cylinder was receiving improper fuel spray patterns. The fuel rail had to be removed to access and replace the defective injector. It was a serious repair that required specialized tools and precise calibration after installation. While not an emergency repair, running with a bad injector can lead to poor fuel economy, carbon buildup, and potential catalyst damage over time. The repair resolved both the cold start issues and eliminated the rough idle completely. Based on your symptoms and mileage, recommend having the fuel injectors tested individually rather than just cleaned. Modern direct injection systems are sensitive to even minor injector problems, especially during cold starts when precise fuel delivery is crucial.

Thanks for sharing that experience with the injector replacement. I had very similar cold start problems with my GL6. The rough idle would last about 2-3 minutes and then smooth out completely. After trying several cheaper fixes, I ended up needing a full injector replacement too. Would you mind sharing what the total repair cost was for your injector work? Also curious if youve had any other fuel injection issues since getting it fixed? My repair was done about 8 months ago and its been running perfectly since, but always good to know what to watch out for.

Glad to hear you also got the faulty cold start injector fixed. The total cost for my injector repair came to 515€, which included removing the fuel rail, replacing the defective injector, and recalibrating the fuel delivery system. Since getting it fixed, the car starts perfectly even on the coldest mornings and I havent experienced any other fuel system issues. The proper fuel spray pattern from the new injector made a huge difference in both cold starts and overall engine performance. For preventive maintenance, I now use high-quality fuel and follow the recommended service intervals for fuel system cleaning. This helps maintain consistent fuel delivery and prevents carbon buildup that could affect injector performance. Modern direct injection systems really need this regular care to prevent similar problems from developing.

After reading about similar cold start problems, I finally took my GL6 to the mechanic last week. The engine misfire during cold starts was getting worse, so I knew it needed professional attention. The diagnostic tests confirmed a failing injector was causing inconsistent fuel delivery. The repair involved removing the fuel rail to replace the faulty injector. Total cost came to 480€ for parts and labor, including the necessary recalibration. While not cheap, it was worth fixing before it could cause more extensive damage. Its been a week since the repair and the difference is night and day. No more rough idle or hard starts in the morning. The engine fires up instantly and runs smooth from the first turn of the key. Really glad I got this sorted out properly instead of continuing with just fuel system cleanings. Thanks for all the helpful advice that pointed me in the right direction. Will definitely keep up with the recommended maintenance to prevent future injector issues.