We went for a run earlier, mainly to fill the tank for winter, because it was down to 1/4, and the GDI hasn't been nout much since Scotland.
After ten miles of normal running, we hit an incline and power vanished. It wasn't a single cylinder misfire, it was one of those brick wall flat misfires. It wasn't exactly safe where we stopped, but not busy either. The engine would tickover normally, but not rev. Just like the VW defeat rev limiter if you are familiar with that, but a lot more coughing and farting. It was impossible to turn round there, so when it cleared we got to the petrol station and filled up with Shell V Power.
It happened again a couple of miles after filling up, but a very mild flat spot. The engine otherwise ran normally. A few miles further and a slightly longer stutter. Within three miles of home it went tickover only. By holding the throttle right down it would stutter and cought then clear momentarily, before dropping t0 tickover again. We made it onto a filling station forecourt but were stuck for about half an hour, it just wouldn't clear. I was then at the point of calling the RAC, but knew that this would write the rest of the day off. Eventually after a lot of boy racer revving, it cleared enough to get home. In the garage it seems fine, but obviously I will be doing some checks.
The obvious cause is water in the fuel, but if so it's taking a long time to clear. The other alternative is the fly by wire throttle, and so I'll clean the contacts when I get time, and also check the Maf Sensor. There's no engine fault light showing.
Has anybody got any other ideas? I don't think it's ignition based. The only change I've made is ro rewrap the exhaust manifold and cat, but I can't see how that would cause this.
