Doblo Combustion Misfire

Misfires can be tricky. When you say 'jerking,' is it consistent, or only under heavy throttle? Have you tried any basic checks, like spark plugs? A bad coil pack could also mimic injector issues, and it's a much cheaper fix. A combustion misfire means that not all of the fuel is burned inside of a cylinder. This can be caused by a number of different issues.

The jerking is most pronounced during moderate acceleration, say, when merging onto a highway. Spark plugs were inspected and appear to be in good condition. Regarding coil packs, is there a reliable method for testing their functionality besides simply swapping them out one by one?

Okay, moderate acceleration jerking points even more towards fuel delivery. While you can test coil packs with a multimeter checking resistance, it's not always definitive. Given your symptoms and the plug check, a faulty injector is highly probable. I'd advise getting it professionally diagnosed. Fuel injection systems operate at high pressures, and fiddling without proper tools and knowledge can be risky. Plus, they can pinpoint exactly which injector is failing. This will save you time and money in the long run.

Thank you for the detailed insights. I took the Doblo to a reputable workshop, and their diagnosis confirmed a defective fuel injector on one of the cylinders. Replacement and recalibration cost 515€. The engine now runs smoothly, and the misfire is resolved.