Buick Regal Hybrid Engine Misfire Fix Guide

As someone with moderate repair experience, I had a very similar issue with my 2016 Buick LaCrosse Hybrid that showed the same symptoms, rough running, jerking during acceleration, and reduced power output. After diagnosis, the problem turned out to be a faulty fuel injector causing cylinder misfire. The combustion misfire was particularly noticeable during cold starts and when accelerating. The ignition coil was initially suspected, but testing revealed the fuel injector was the actual culprit. Had it fixed at a workshop where they replaced the defective injector. Total repair cost came to 515 Euro including parts and labor. Since the repair, the engine has been running smoothly with no more misfiring issues. To better assist with your specific case, could you share: Current mileage on your Regal, When did the symptoms first appear, Whether the check engine light is constant or flickering, If you have access to the error codes, Whether the issue happens more during cold starts or warm engine This information would help determine if you are dealing with the same fuel injector issue or potentially something else causing the engine misfiring.

Thanks for sharing your experience. My Regal is at 189889 KM and the last full service was done 2 months ago. The cylinder misfire and rough running started shortly after. The check engine light stays constant rather than flickering. Got it scanned and showing P0303 code. Since you mentioned fuel injector problems, I checked with the service center. They focused mainly on testing the ignition coil and throttle response but did not specifically look at injectors. Given the similar symptoms, I will have them check the fuel injection system on my next visit. The engine misfiring gets noticeably worse when the engine is cold, which seems to match what you experienced. This additional insight about checking the injectors specifically is really helpful.

The cold start symptoms and P0303 code you mentioned definitely align with my fuel injector experience. While the ignition coil and throttle response testing is good practice, the fact that your issues started after a service makes me think they might have disturbed something in the fuel system. When my LaCrosse had the rough idle and combustion misfire issues, the mechanics initially focused on spark plugs and coils too. But the problem persisted until they specifically tested the fuel injector flow rates. They found one injector was partially clogged, causing inconsistent fuel spray patterns. A few indicators that pointed to fuel injector problems in my case: Rough idle that worsened during cold starts, Jerking specifically under acceleration, Engine misfiring that became more pronounced over time, Constant check engine light rather than intermittent Consider requesting a fuel injector flow test and pressure check of the entire fuel system, including the fuel pump. My repair solved not just the misfire but also improved overall throttle response and eliminated the cold start roughness completely.

Thanks everyone for the detailed responses. Just wanted to update that I took the car back to the shop and specifically requested fuel injector testing based on the feedback here. Turns out cylinder 3 had a failing injector, just as suspected given the similar symptoms. The fuel injector replacement cost came to €485 including labor. They also did a full system pressure test and cleaned the remaining injectors while they were at it. The throttle response is now much smoother and the engine misfiring has completely stopped. Most importantly, no more rough running during cold starts. Really appreciate the suggestion to look beyond just ignition coils and have them check the fuel system. Would have likely spent more time and money troubleshooting without that specific direction. The combustion misfire symptoms clearing up right after the injector replacement confirms this was definitely the core issue. Will keep an eye on things but so far running perfectly after a week of regular driving. Good to have this resolved before it potentially caused any additional engine damage.