My 2004 Hiace petrol 2.4EFI has days where it rattles like a diesel. It sounds like the rocker gear is about to jump out of the engine and have tried every fuel and oil and had it serviced regularly by both Toyota dealers and a local mechanic. Only solution that works every time is a 500 ml bottle of injector cleaner/octane boost added to the fuel tank. Can get it to go away for a few weeks if I use E10 fuel, silly as it is lower octane , ie poorer quality which the cleaner seems to suggest the engine needs better fuel grades. Have even run it on 100 octane, but no better. This happens especially on very dry days, have had it at 6am in the cold , noon in 100 degree heat, pulling a trailer with a loaded van and with the van completely empty and only the driver on board.
