We were drivng along towing our caravan when our Discovery just lost power and all of this black smoke started coming out of the exhaust. We turned the engine off and then turned it back on and it started right away and on we travelled. Our mechanic scanned the computer and it indicated the number 1 injector had stayed open. We have now lost power and re-started quite a few times since - always on long journeys. The last time it took a while for the car to re-start. Does anyone have any ideas what we should do to fix this problem? Thank you for your time and hopefully any solutions.