Originally Posted by Leemanfor
my last car was DI and i never experienced random misfires or really any issues due to valve coking, and they were pretty bad when I got around to cleaning them with solvent and walnut blast. I did notice a bit better gas mileage once I did it but I went almost 100k with no AOS or cleaning.
A low ash oil helps also.
I'm probably still hung up on the horror stories from Audi and BMW owners. I understand that there are a number of tricks available to manufacturers with valve timing and such to lessen the risk of buildup, and I feel like we'd have seen a number of complaints over on nabisco if FA20 valves were getting buildup like the BMW N54s were.