Did any manufacturer solve DI engine carbonization issue?

[accel]

On the market for another car during oncoming year. There's a lot of DI engines percentage wise. Like almost all Mazda and Subaru lineup.

I owned DI car in the past and that experience did not go really well. I got rid of that car and would like to avoid having one ever again.

Unfortunately some of the cars that would be nice to have otherwise are having pure DI engines...

My question is - did any manufacturer solve carbonization issue in a reliable way in the last few years?

I know of special cases like di with port injection hybrids like current coyote and some other specific models have - frs/brz/86, but those are exceptions.

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[ice445]

Other than MPI, nope. They all will carbon up without upstream injection as a secondary. Some are worse than others.

 

[Balr14]

I believe it is not an issue with Porsche, something with the angle the fuel enters the cylinder. It also washes the back side of the valves. In all the time I owned a 911, nobody ever mentioned carbon build-up as an issue.

 

[accel]

I believe it is not an issue with Porsche, something with the angle the fuel enters the cylinder. It also washes the back side of the valves. In all the time I owned a 911, nobody ever mentioned carbon build-up as an issue.

Not too many, true.

Here's one:

https://rennlist.com/how-tos/a/porsche-997-why-your-car-is-experiencing-carbon-build-up-383731

Interesting is that they mention stock oil air separator in the article ^. Does that mean Porsches have it ? I thought noone provides oil catch can as a standard equipment.

Here's another one with picures.

https://www.renntech.org/topic/26036-dfi-engine-issues/

 

[Balr14]

AOS is standard equipment on a Porsche. I replaced mine because I screwed up, but that is uncommon. If you are going to seriously track a 911, you may have issues. But, most street cars are not meant to withstand the heat buildup you get on the track.

 

[Shifting_Gears]

This “problem” is probably good business for dealer service departments. Carbon buildup issues probably won’t create drivability issues until after the warranty is up.

The average consumer doesn’t know or care about DI vs regular fuel injection and the fact there’s some long term reliability questions surrounding it. Like people who buy a car with a CVT trans, most don’t care but the dealer isn’t going to tell you they’re likely to fail well before an equally maintained traditional transmission.

 

[accel]

This “problem” is probably good business for dealer service departments. Carbon buildup issues probably won’t create drivability issues until after the warranty is up.

The average consumer doesn’t know or care about DI vs regular fuel injection and the fact there’s some long term reliability questions surrounding it. Like people who buy a car with a CVT trans, most don’t care but the dealer isn’t going to tell you they’re likely to fail well before an equally maintained traditional transmission.

I've heard an opinion that DI is a straight cheat from fleet fuel economy, emissions and other corporate test's point of view as well. The car passes all of those tests very good and demonstrates good MPGs as long as it is in like new condition. Once the car leaves delaer lot and becomes not new - not manufacturers issue.

So as a buyer you should expect fuel economy, hp/tq, 0-60 and other times to be not as promised after several kmiles. This might be Ok if you buy a corolla or sentra, but if you pay big bucks for a performance car then I'm not sure how happy one could be.

My personal experience was that carbon buildup became very bad in a very short period of time, then apparently pieces of it broke and blocked valve(s). The engine wouldn't start. It took 2 weeks 2 remove engine head, send it to machine shop and clean. The bill for the repair looked to me more like car mileage than financial figure, but I was under warranty at that time.

 

[Shifting_Gears]

I've heard an opinion that DI is a straight cheat from fleet fuel economy, emissions and other corporate test's point of view as well. The car passes all of those tests very good and demonstrates good MPGs as long as it is in like new condition. Once the car leaves delaer lot and becomes not new - not manufacturers issue.

So as a buyer you should expect fuel economy, hp/tq, 0-60 and other times to be not as promised after several kmiles. This might be Ok if you buy a corolla or sentra, but if you pay big bucks for a performance car then I'm not sure how happy one could be.

My personal experience was that carbon buildup became very bad in a very short period of time, then apparently pieces of it broke and blocked valve(s). The engine wouldn't start. It took 2 weeks 2 remove engine head, send it to machine shop and clean. The bill for the repair looked to me more like car mileage than financial figure, but I was under warranty at that time.

Yeah, all of that seems plausible. Thankfully your experience was covered under warranty. BMW seems to have pioneered the walnut blast to remove carbon buildup and it's been adapted to other platforms. It's probably a pretty common service now.

I had a Focus ST, which was DI, and part of my reason for trading it in was due to long term reliability concerns. I could feel the engine was not as responsive (I had about 74k on the odo) later in life and that was one of my worries.

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