Want to add something here because I had similar kind of as soon as I bought my previous FB15 which had the same engine. I felt intermittent " taka taka" noise when I tried to accelerate with even 95 octane petrol. Engine was troubling to rev up beyond 3000 RPM. No fault codes no check engine sign. But the problem was with MAF sensor. Don't know whether it help or not in this scenario.