Buick Verano Shakes: Bad Plugs vs Injector Diagnosis

I experienced similar symptoms with my 2012 Buick Regal. The check engine light and jerky acceleration turned out to be a combination of issues. The main culprit was worn spark plugs and a failing ignition coil. The rough running was particularly noticeable during acceleration, just like your case. A diagnostic scan revealed misfires across multiple cylinders. The old spark plugs showed significant wear with large electrode gaps. After replacing all spark plugs and one faulty ignition coil, the engine returned to smooth operation and the check engine light stayed off. Your symptoms match what I dealt with. At 50k miles, the original spark plugs in your Verano could be reaching their replacement interval. While checking the plugs, have the mechanic inspect the ignition coils and crankshaft sensor as these can cause similar symptoms when failing. This was a straightforward repair that prevented more serious engine performance issues down the line. Best to address it promptly to avoid potential damage to the catalytic converter from continuous misfiring.

Thanks for sharing that experience, it sounds exactly like what my Verano was doing last year. My engine had a rough idle and was misfiring during acceleration. The mechanic found that both the spark plugs and an oxygen sensor needed replacement. Did you remember roughly what the repair cost came out to? Also curious if youve had any similar engine performance issues since getting it fixed?

Had the repair done last month and glad to report the uneven engine running has been completely resolved. The mechanic traced everything back to a leak in the exhaust system that was causing incorrect readings from the oxygen sensor, leading to that rough idle and engine misfire you mentioned. Total cost came to 265€ including the repair of the exhaust leak. Since the fix, the engine runs perfectly smooth with no performance issues at all. No more jerky acceleration or check engine lights. The air filter was also pretty dirty during inspection so they changed that too while they were at it. If your symptoms are similar, definitely worth having them check the exhaust system along with those spark plugs. Been driving it daily for the past few weeks and honestly feels like a different car now, super smooth acceleration and steady idle. Having an exhaust leak can really throw off the whole system, especially how the oxygen sensor reads the fuel mixture.

Thank you for the helpful information. After dealing with those frustrating symptoms, I finally got my Verano properly diagnosed and fixed last week. The mechanic found multiple issues, worn spark plugs creating misfires and a faulty oxygen sensor giving incorrect readings. The total repair came to around 400 Euro including parts and labor. The difference in performance is remarkable. No more jerking during acceleration and the check engine light has stayed off. The idle is smooth and steady now. The mechanic showed me the old spark plugs and they were definitely overdue for replacement. They also cleaned the fuel injectors while everything was apart. Really glad I got this resolved before it could cause any additional problems. The car runs like new again and I feel much more confident driving it. Thanks again for helping point me in the right direction with the diagnostics.