Sprinter Engine Misfiring Diagnosis

Engine misfiring can be tricky. A bad spark plug could definitely cause a rough idle and reduced throttle response, mimicking some of your symptoms. Have you checked the spark plugs for wear or damage? Also, a failing fuel pump can definitely lead to engine misfiring due to insufficient fuel delivery, especially under acceleration. Have you noticed any unusual noises coming from the fuel tank area? It's also worth considering a faulty ignition coil. Have you checked if any specific cylinders are misfiring using an OBD2 scanner? That information could help narrow things down.

Thanks for the quick response. I haven't personally checked the spark plugs yet, but I was planning to do so this weekend. Regarding the fuel pump, I haven't noticed any unusual noises, but I suppose that doesn't rule it out entirely. I do have an OBD2 scanner, and it's reporting misfires on multiple cylinders, but it doesn't seem to pinpoint a specific one. If it's multiple cylinders misfiring, does that make a faulty fuel pump or perhaps even bad fuel more likely than individual ignition coils or injectors?

Since you're seeing misfires on multiple cylinders, a fuel pump issue or bad fuel seems like a more probable cause than individual ignition coils. Though, it's still difficult to say for sure. The fuel pump not providing enough fuel could cause widespread misfires. Similarly, contaminated or low-quality fuel could affect multiple cylinders. Given the complexity and the potential for further damage, maybe consider getting it checked by someone experienced. It's hard to diagnose remotely, and you might save money in the long run by avoiding further misdiagnosis.

Thanks for the advice. I took it to a workshop. Turns out it was indeed a defective injector. They replaced it, and the engine is running smoothly again. The total repair cost was 515€ Appreciate the help!