DI engine question
- Thread starter volk06
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Not sure if you saw this article:
http://www.autoobserver.com/2011/06/direct-injection-fouls-some-early-adopters.html
So I think the issue is less about oil and fuel quality, and more about designing better crankcase ventilation and exhaust-gas recirculation components to prevent crud from getting to the valves in the first place.
Do we know if the issues is also as prevalent in Europe where gas quality is better? Granted, they also have different emissions requirements, which may not require as much of the exhaust gasses to be put back through the intake manifold.
Quote:
All modern gasoline engines return some crankcase and exhaust gases back through the intake manifold in order to help control emissions, but, according to Chick, some exhaust-gas recirculation designs are “dirtier" than others. Some, he said, are less-effective at preventing the passage of tiny bits of oil, carbon and other particulates that eventually get baked onto the intake ports and valves.
The simplest reason I can think of is that fuel doesn't wash the valves. Thus any PCV "dirtiness" gets magnified.
Even a high quality oil will have a noack of 8 or 10 percent. So that's literally ounces of oil that will vaporize over the course of an OCI.
I unfortunately don't think there is any way to prevent deposit build-up, just slow it maybe, use a low NOACK vol. oil and MMO (in oil and gas) and pray.
Toyota has a unique way, though it's complicated. They use a secondary injector upstream to help wash the deposits.
Catch cans and low volatility oils help but do not completely fix the problem. Regular carbon cleaning is necessary.
Originally Posted By: volk06
How do you do this carbon cleaning? Can of seafoam before an oci?
DI is a whole different beast from anything before. Some have had problems with it, like VW for sure. It's too early to tell, but some people are saying that GM did something different with their DI engins that inhibit deposits- is this true, who can say? I certainly hope so though, as the equinox has a Direct-Injected V6.
Originally Posted By: Nick R
It's too early to tell, but some people are saying that GM did something different with their DI engins that inhibit deposits- is this true, who can say? I certainly hope so though, as the equinox has a Direct-Injected V6.
Quote:
Haider, GM’s V6 assistant chief engineer, explained how GM has designed its DI engines to combat carbon buildup: “We maintain great engine function and performance in our all our DI engines through an optimization strategy with our valve events,” he said. “Our intake-cam timing, injector targeting and timing of the injection events are optimized to avoid direct fuel contact on the intake valves. This strategy keeps smoke and soot formation to an absolute minimum, which in turn prevents excessive deposit formation.”
At the Detroit Auto Show in January, Ford was confident enough about its popular 3.5 liter EcoBoost direct-injection V6 to have technicians tear down an example engine that had accumulated the equivalent of 160,000 miles through an intentionally abusive regimen of log dragging, high-speed towing and desert racing. When they opened it up before a live audience, they found some light carbon deposits on the valves and pistons, but not enough to affect performance. In fact, the engine showed a loss of just one horsepower afterwards – roughly what Boyadjiev’s RS 4 engine lost every 500 miles.
Running the fool out of the DI engine isn't going to cause the carbon buildup like the day-to-day, stop-and-go of normal driving will, IMO.
Put the engine in a taxicab and see how fast it carbons up.
Some said it is caused by fuel vapor instead of engine oil vapor, and some said it is the overlap of exhaust stroke and intake valve opening that causes deposit. In the end it seems like the newer design from GM has gotten good enough to not have problem, Toyota's seems to need cleaning once every 15-30k miles by spraying solvent directly at the intake valves, and VW/Audi need excessive cleaning with some dismantling.
When I had my Lexus, the 250 engine seemed to be the one with the problems and the 350 engine I had didn't seem to have any of the problems. Of course, from my understanding (minute though it is) the 350 had a 'hybrid' direct and port injection set up.
Originally Posted By: volk06
How do you do this carbon cleaning? Can of seafoam before an oci?
Originally Posted By: MarkM66
Originally Posted By: volk06
How do you do this carbon cleaning? Can of seafoam before an oci?
Originally Posted By: The Critic
Originally Posted By: MarkM66
Originally Posted By: volk06
How do you do this carbon cleaning? Can of seafoam before an oci?
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