As petrol engines in new Jazz, HR-V, Civic Type-R and future Honda petrol engines are likely to be direct injection I sent an email dated 13/09/2015 to Richard Clissold, Customer Relations Technical Advisor, Honda UK, asking: “What measures are taken by Honda to prevent coking up of inlet valves due to crankcase fumes now having to be burnt off in the engine? I understand that Toyota have introduced secondary port fuel injection on their direct injection engines so that oil fumes deposits are washed off the inlet valves.” I never had a reply so have asked the service manager of my local Honda dealer, Norton Way at Letchworth, if he can find out. To minimise the problem of inlet valve coking up some advise using top grade petrol & fuel additives but if fuel in direct injection engines does not pass inlet valves this will be futile but will probably extend life of the direct injection injectors. Others suggest adding catch cans, but these will only delay the problem. I would not touch a direct injection petrol engine unless it had dual port fuel injection as some Toyota & Audi/VW engines now have. Even then expensive high pressure injectors are likely to be less reliable than lower cost lower pressure port injectors. Ask An Engineer: GDI Problems In A Nutshell - The Truth About Cars may have to stop script running to see this article as many comments follow it.