High speed hesitation - 2.5 KV6

[Snapoff Jon]

Bit of an esoteric one this..

I've just taken my KV6 2.5 Rover on a grand tour across 7 countries in 5 days - about 1,700 miles in total. This included driving it over the 2,000m San Bernadino pass in the Swiss alps..

Generally, the car performed brilliantly - except that occasionally when cruising on the motorways at about 80mph and going up a slight incline the engine would very briefly (and we are talking one or two tenths of a second) cut out. This didn't happen regularly and whole days would pass when the car ran completely smoothly right up to three figure speeds (on the Autobahn off course..!).

My initial feeling was that it was a fuel pressure issue - though under hard acceleration it did not occur.

When I bought the car it had a burnt exhaust valve which I replaced along with the plugs, two front coils, HT leads, timing belts, thermostat and cam sensor. I also fitted a replacement electric fan.

I'm now wondering whether the problem is caused by the engine running lean.. Perhaps an oxygen sensor issue?

I have left the car at an airport in France - plan to use it for a few weeks during the Summer holidays with the family. I have the pscsan OBD2, though won't be able to look at any fault codes until I next use the car.

Any suggestions for what this could be?

Thanks!

[roverbarmy]

Many years ago, I had a Rover V8 which would do this occasionally in hot weather. It seemed that the fuel would overheat in the carb bowls and vapourise before it should (you could literally hear the fuel boiling!). I wrapped the fuel line in the engine bay with insulation - problem solved. I know that you don't have carbs but a similar principle might be in operation?:shrug:
Mike