The operative point: "The change will eventually impact nearly every direct-injected gas engine the VW Group makes." Port injection avoids the problem. But direct injection, even the well modulated versions run into the problem of incomplete mixture, burning fuel while there are still particles or local concentrations. It is the nature of the beast. Bob Wilson
Mind you, in Europe, the Gen 3 EA888 actually also has port injection for lower power demand operation. Ours, on the other hand, does not. But, at high power demands, these engines (including Toyota's D-4S engines) all go into direct injection, and therefore have poor mixing... The other problem with running port injection is that it doesn't work well with the downsize-and-turbocharge strategy (even GM's now moving away from port injection in their downsize-and-turbocharge 1.4Ts), especially when trying to replace a diesel engine's low-end power delivery to make up for the taller gearing that downspeeding calls for. Ultimately, though, I'm for upsize and Atkinsonize (while still downspeeding) instead, and with that kind of strategy, DI is much less important. Get the engines running slow enough, and pushrods may even make sense to make upsizing work even better (longer stroke, taller engine, compensated for by not having the cam at the top).
Pure speculation on my part but I wonder if the injected fuel could be pre-heated as part of the injection process. I'm thinking of how HP inkjet printers work by vaporizing a small amount of ink to generate the stream. If the fuel can be super-heated without causing it to decompose into solid carbon compounds, coming out super-heated might be just the thing to reduce particulates ... then I realize, no it won't. You'll still have that locally rich, area forming soot instead of combustion. Particulates would predominate over oxidization. ... Another day-dream crashing into reality. Bob Wilson
Port injection emits particles. The large majority of PI engines only emit enough to stay under a limit likely selected by lobbyists and lawmakers to keep them free of exhaust filters when the filters were mandated for diesels. Some PI engines have gone over that limit. EU regulations already call for exhaust filters on DI engines. There is just a hold in place on enforcing it, but that is likely set to expire soon. US testing currently just turns a blind eye to testing particle emissions on all gasoline vehicles. The article isn't clear on whether VW announcement is for all their gas DI cars, or the ones for the European market.
It is a requirement in Europe that has been put on hold, but will likely go effect sooner rather than later. Meeting before then it is good for PR. If VW is putting the filters on cars outside of Europe, it is more marketing ploy.
