We recently bought a 64-plate Fiesta EcoBoost 1.0 which has a recurring but intermittent fault. During acceleration (from about 2500 rpm upwards) there is sometimes hesitancy in its power delivery that feels like misfiring. This sometimes, but not always, leads to the engine putting itself into some kind of safe mode where it limits the rev range strictly to 2000rpm. The problem usually happens when it is fully warm, often about 15 minutes into a journey. It has done this roughly eight times within the last two months – but, of course, never when it’s at the dealership. I think that they think we’re making it up.

The thing is, no engine problem/management lights or messages are displayed on the dash and no entries are ever made into the engine management unit’s log. We and our main Ford dealer are having real trouble tracking down the cause, so I would be interested to hear from anyone who has experienced similar issues.