Vauxhall Adam running rich

Sounds like a potential fuel injector issue, leading to an incorrect air-fuel ratio. When was the last time you changed your air filter and spark plugs? A clogged air filter can restrict airflow, enriching the mixture, and worn spark plugs might not be burning the fuel efficiently, causing similar symptoms. Have you scanned the OBD for any error codes? That might point you to the faulty cylinder. A defective injection valve is a common cause for your symptoms.

Thanks for the quick reply! Air filter was changed recently, but the spark plugs are probably due. I did scan it and it points to a misfire in cylinder 3, so the injector issue seems likely. How can I be 100% sure it's the injector?

Given the misfire code for cylinder 3 and the rich running symptoms, a faulty injector is highly probable. You could try swapping the injector from cylinder 3 with one from another cylinder and see if the misfire moves. However, without specialized tools for testing fuel pressure and spray patterns, it's difficult to confirm definitively. Considering the symptoms and mileage, I would recommend taking it to a workshop for a proper diagnosis and repair.

Thanks, I appreciate the advice! Took it to a shop, and you were spot on – faulty injector on cylinder 3. Replaced it and everything is running smoothly again. Cost me 515€, all in.