[Marty McFlew]

Anyone have one with high mileage yet? What can be expected regarding top end problems with gunk as the miles add up? Will they eventually experience performance issues and need an expensive top end cleaning?

[Boilermaker128]

You won't know for a LONG time with DI'S. Highway driving is better for a DI vehicle so look for the ones that get driven short trips, use cheap gas, let oil changes go extra long, use shitty oil, high load low gear driving, etc. My DI has 252,000km and I don't notice any difference in mpg or power, never used a catch can or walnut blasting/sea foam brush cleaning. But a walnut blast is only about 5 hours/15 beers and $100 in materials on an LNF if need be.

[Hyper16]

Hasn't this same engine been in Corvettes for a few years? Maybe a Corvette owner could answer.

[Jeb114]

This is from Consumer Reports.
So what’s up with direct injection?
First, a primer on how it works: By injecting gas*oline at high pressure directly into the engine’s combustion chamber, direct injection more precisely measures fuel than conventional fuel-injection systems or old-time carburetors.

The result is more complete combustion and cooler cylinder temperatures that enable a higher compression ratio for greater efficiency and power. Engine technology supplier Bosch says that direct injection can return a 15 percent gain in fuel economy while boosting low-end torque as much as 50 percent.

Combining direct injection with other technologies—such as turbocharging—can deliver even greater gains in economy and performance. That in turn enables carmakers to use smaller displacement engines, resulting in an efficiency snowball effect. Many automakers are marketing DI as pro*viding fuel economy that’s almost as good as a hybrid’s, and with better performance—but without the $4,000 hybrid premium.

Although the breakthrough seems like a dream come true, an unwanted side effect has been emerging. Letter writers have complained to Consumer Reports and the National Highway Traffic Safety Administration (NHTSA) that over time DI can lead to clogged fuel systems and engine carbon buildup. The result can be engine hesitation and a loss of power—and the need for expensive repairs.

Some carmakers, including BMW and Kia, have issued technical service bulletins (TSBs) to their dealers recommending that drivers use only name-brand detergent gasoline—without ethanol additives—and that they periodically add a fuel-system cleaner when they refuel. (A TSB is an alert that the automaker sends to dealers to warn about ongoing problems with individual models and how to fix them. It may allow dealers to make repairs at little or no cost to the customer as a goodwill gesture.)

Other automakers have devised an engineering fix that works while the car is oper*ating. It involves modifying the engine to spray a small amount of fuel directly onto the valves to help keep them clean.

It’s important to note that not all cars with direct injection experience long-term problems. But if your engine stumbles more than it used to, or it suddenly lacks power, ask your dealer about it. A fix may be available, and you may not have to pay for it.

[Zeke.Malvo]

Originally Posted by Boilermaker128

You won't know for a LONG time with DI'S. Highway driving is better for a DI vehicle so look for the ones that get driven short trips, use cheap gas, let oil changes go extra long, use shitty oil, high load low gear driving, etc. My DI has 252,000km and I don't notice any difference in mpg or power, never used a catch can or walnut blasting/sea foam brush cleaning. But a walnut blast is only about 5 hours/15 beers and $100 in materials on an LNF if need be.

I think a before dyno and after that mileage (kilometerage?) dyno would be a better indicator.

[Boilermaker128]

Too late for me now but it is a good idea. Maybe I can do a Dyno, walnut blast, dyno. But I'm working 80 hour weeks for the next two months, maybe after Christmas. Point is it's not noticeable enough for an owner to worry too much about, it can be fixed, with walnut goodness.

[Ernest T]

I own a 2015 C7 and there are never ending discussions on the Corvette forum about direct injection and the necessity of a catch can to eliminate valve train gunk buildup. The bottom line is there are several members with over 100K on their cars already and no performance issues. No one has removed the heads on their cars to look at the build up though. I would assume that GM ran the engines for a very long time and then disassembled them to do wear measurements when the engine was in development. I think they would have addressed any gunk build up then. GM says no catch can needed on a C7, but doesn't the Camaros have a catch can stock?

[Hyper16]

Originally Posted by Ernest T

I own a 2015 C7 and there are never ending discussions on the Corvette forum about direct injection and the necessity of a catch can to eliminate valve train gunk buildup. The bottom line is there are several members with over 100K on their cars already and no performance issues. No one has removed the heads on their cars to look at the build up though. I would assume that GM ran the engines for a very long time and then disassembled them to do wear measurements when the engine was in development. I think they would have addressed any gunk build up then. GM says no catch can needed on a C7, but doesn't the Camaros have a catch can stock?

No, not stock but a lot of folks are adding them.

[Whis]

Originally Posted by Hyper16

No, not stock but a lot of folks are adding them.

It's a shame something so simple voids the warranty

[MovieGuy]

Originally Posted by Whis

It's a shame something so simple voids the warranty

It voids the warranty?

[MovieGuy]

This is an interesting article
http://www.underhoodservice.com/dire...rbon-deposits/

[cellsafemode]

A dealer can say anything is "voiding the warranty". Whether you press the issue or not is up to you because it it gets to a court, they have to prove that your modification caused the problem and good luck proving that a in-line can caused oil blow by to occur upstream of the can greater than if it hadn't been there. The physics just doesn't work that way.

I think many publications are saying to just treat your car to valve cleaner once a year and you'll be fine. Something like seafoam or other intake valve cleaners should do the trick.

[laborsmith]

Per several threads on the Corvette Forum GM will void the powertrain warranty for any Corvette presenting with engine problems and a catch can is installed or evidence of a catch can had been installed. These threads arise when a forum member posts the power train warranty voided for engine failure and the presence of a catch can is detected.

Laborsmith

[MovieGuy]

Originally Posted by cellsafemode

A dealer can say anything is "voiding the warranty". Whether you press the issue or not is up to you because it it gets to a court, they have to prove that your modification caused the problem and good luck proving that a in-line can caused oil blow by to occur upstream of the can greater than if it hadn't been there. The physics just doesn't work that way.

I think many publications are saying to just treat your car to valve cleaner once a year and you'll be fine. Something like seafoam or other intake valve cleaners should do the trick.

Where do you apply the valve cleaner?