jonaskoehler6

Accent rough running issue

My 2004 Hyundai Accent with a gasoline engine is having issues: reduced engine power, check engine light, rough running, and jerking when accelerating. Sometimes it stalls. My OBD scanner shows mixture preparation errors. I've checked for vacuum leaks, cleaned the mass airflow sensor and throttle body, but the air-fuel ratio is still off. I suspect it's the injection valve(s), any thoughts before I dig deeper?

A 2004 Hyundai Accent is experiencing reduced engine power, a check engine light, rough running, jerking during acceleration, and occasional stalling. The OBD scanner indicates mixture preparation errors, and initial checks for vacuum leaks and cleaning of the mass airflow sensor and throttle body did not resolve the issue. The suspected cause is faulty injection valves, with one injector showing resistance out of spec. The suggested solution is to replace the injectors, which ultimately resolved the problem.

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4 comment(s)

Sounds rough. I had similar issues with my Accent. I'd start by looking at the injectors. A faulty injector can definitely cause a rich mixture. Have you scoped the injector waveforms or measured their resistance? It could also be fuel pressure related, so check that regulator!

Good call on the fuel pressure regulator, hadn't considered that. I haven't scoped the injector waveforms yet, but I did measure the resistance, and one seems a bit out of spec. You think it's worth trying to clean them first, or just replace the whole set?

Honestly, based on my experience, cleaning them is a gamble. It might work temporarily, but I ended up replacing mine anyway. Given the symptoms you described and the resistance reading, it’s probably a defective injector. Save yourself the headache and just replace them. I know it's not cheap but it fixed it for me. If you're not sure, it is best to go to the workshop and be sure.

Appreciate the input. I'm leaning towards replacement too. Just wanted a second opinion before dropping the cash. Turns out you were right, it was the injectors. Replaced all four and that smoothed everything out. Cost me 515€ in total, including labor. Thanks!

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HYUNDAI

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ACCENT