VNAMVET

So in Volkswagens, it does. Is direct injection different on our general motor Corvettes than Volkswagens direct injection?

robertf97

Its got to do with how the PCV system is designed and how much oil vapor is created which will vary from engine to engine. Supposedly GM went to great lengths on the C7 with the baffles in the valve covers to reduce the amount of oil ingested. I would reroute the PCV and/or use a catch can based on all the oil ingestion issues I've seen posted here.

meyerweb

That article refers to a 2006 VW. I can't help but think the technology has improved a little bit in the last 9 years.

But if you're really worried, make sure you use Top Tier gasoline:

http://www.toptiergas.com/

Theta

I'll take a picture if I still have my stock ones around here - they really did a lot of work with 'louvering' the valve covers.

The DI cars (especially EU manufacturers) of the last two generations have paved the way for better technology across the industry. The early examples (this 2006 VW being a great example) were fraught with problems, while the latest-gen EU and US models don't really have enough data to make a conclusion.

For now, we'll just have to hope.

1BADLS3

Care to explain how top tier gas would make any difference? The fuel never passes by the intake valves in DI engines.

Rave

If you do some research on this Forum and youtube and you'll find the type of gas you use will make little or no difference if you have a Direct Injection engine. You will eventually build up Coking on the intake valves over time and eventually loose some power. Adding a Catch Can helps.

meyerweb

Good point. I was thinking about carbon buildup in the cylinder heads, rather than the valves.

FYREANT

This is the biggest pitfall with DI. I would like to see this question asked to Tadge to see what the Corvette team has to say about it. Discuss it more here as well:

https://www.corvetteforum.com/forums...on-valves.html

Ant

Higgs Boson

the term direct in direct injection refers to the fuel being injected "directly" into the cylinder/combustion chamber, which is also below (past in terms of airflow) the heads.

Rave

This short video explains the Direct Injection issues pretty well:


I think DI engine technology will eventually evolve to solve the problem. While some manufacturers choose to ignore the problem, as the video states, other manufacturers are starting to address the problem.

tblu92

It touches the tops of both valves--and the piston and the entire combustion chamber-----That's plenty !!

PLUS Use of injector cleaner with DI becomes less effective on cleaning valve stems and the seat area---But it still can be done by the deep cleaning process with SEAFOAM---

NGS

So, here is one picture from my son's 2010 Audi Q5 V6. Every valve looked exactly like this one. No doubt there is an issue with direct injection and it would be wise to use some type of cleaner like Seafoam every 15-20K.

BTW...he uses top tier premium and I add a can of Techron to his tank every 8-10K...but obviously that makes little difference.

NoOne

So is it just use SeaFoam or something similar every year?

I've done it to my other cars, had a few high mileage LS1's that were swaps into other cars so I ran a can through.

Except for the neighbors hating me it seemed to work pretty well.

tblu92

A catch can on these engines is more important than ever--On any DI engine---The only contamination that can cause such a wet carbon mess on the valves as on the Audi---Is from oil ingestion via the PCV system----I just had my intake manifold off for porting--and all the intake valves were bone dry with just a light dusting of GRAY powder ( 2000 miles)
UPR catch can from day 1-----------

meyerweb

Yeah, I know. I just wasn't paying close attention when I read and replied.

Theta

There's also the 'get-it-so-hot-it-burns-off' method that BMW guys use... Not great for the motor, but done once a year, I can't see it doing much harm. Involves running at a sustained 4000rpm for 20 minutes if I remember correctly.

Seafoam has been hit-or-miss on the N18, N20, etc. Can't comment on the LT1/LT4.

Sir Nuke

well I personally have been driving 4 different GM vehicle for the last 7 years......I had 2 of them at the same time.....ALL of them had a D.I. engine in it.....3 of them only required Regular Gas....and I never bothered to ensure that I put "Top Tier" gas in them, the Vette.....its requires Premium and I will put Top Tier in it.....BUT not one of these vehicles have EVER been into a shop for any reason other than for a Oil/Filter Change. The first two had right 100K miles on them when they were traded in...... I have no fear of D.I. engines at all.....if fact I prefer to have one.

carlrx7

This is the main reason I bought a VW Tdi...

<yt>https://www.youtube.com/embed/xIijYgvxW0g</yt>

so metal!

Rave

That's a wild way to clean an intake! Looks to be very effective.

I have no doubt DI engines can and do last a long time without adding a Catch Can, although there's a lot of evidence that DI engines do ingest PCV fumes and Catch Can's can help.

The C7 in the video below shows how much oil deposits and valve coking accumulate after only 5500 miles. At the 7 minute 40 second point in the video a link will pop up which will show what the inside of the intake and intake valves look like on this low mileage C7.

meyerweb

Did I miss something in that video? They disconnected the hose from the dry sump oil tank to the intake, but I didn't seem them reconnect anything there nor plug the connections that the hose used to attach to.