Skyactiv Intake Valve Deposits - Photos

buster

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Originally Posted by DBMaster
I don't think those deposits look that bad. The Skyactiv engines have significantly higher compression than average (13:1). Part of the way that is achieved is through the use of special rings. Mine has 116,000 miles on it and I have been using 0W-20 for the entire time. I was going 30,000 miles between oil changes when microGreen filters were still available. Now, I'm at 15,000 mile OCIs with Mobil 1 0W-20 EP. I have never had to add make-up oil. So, I'm either getting fuel in the oil that offsets oil loss or the 0W-20 isn't leaking any measurable amount of oil past the rings. My UOA after 30,000 miles didn't show significant fuel dilution.
DB, have you ever posted a UOA? That would be interesting to see.
 
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I do own a Mercedes with OM648 Engine, Direct Injection and Turbo I have almost 122k Miles on it and there has been no issue with carbon spot build. I'm not going to worry about it.
 
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Originally Posted by buster
Originally Posted by DBMaster
I don't think those deposits look that bad. The Skyactiv engines have significantly higher compression than average (13:1). Part of the way that is achieved is through the use of special rings. Mine has 116,000 miles on it and I have been using 0W-20 for the entire time. I was going 30,000 miles between oil changes when microGreen filters were still available. Now, I'm at 15,000 mile OCIs with Mobil 1 0W-20 EP. I have never had to add make-up oil. So, I'm either getting fuel in the oil that offsets oil loss or the 0W-20 isn't leaking any measurable amount of oil past the rings. My UOA after 30,000 miles didn't show significant fuel dilution.
DB, have you ever posted a UOA? That would be interesting to see.
I have, but I'm too lazy to search for it. It's out there on this site, though. It showed what I was looking for - that my 30,000 mile oil was still serviceable and had adequate TBN.
 
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Originally Posted by Eddie
I'm impressed how clean the valves are compared to some other DI engines photos. Ed
Totally agree. DI has led to some horror show pictures, these aren't them.
 
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Arizona
Originally Posted by carviewsonic
Some build-up on the valves and ports, but not the horror show I've seen on photos of some other direct injected engines. I wonder if a catch can would have made any difference? Need to find someone who has driven the same car as you in exactly the same way, but with a catch can grin . It's hard to know how effective they really are.
I think I understand the point, but Mazda _has_ a 'catch can' on their Skyactive-G engines from the factory. That may be one part of the overall reason they (now) experience less or slower carbon build-up than others (or than the first-gen Mazda turbo DI engines did).
 
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Maybe hit the ‘sport' button on trans and some weekly 6000 RPM to clean out the cobwebs ? My daughter has the 2.5L in her Mazda3, great engine. 👍
 
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Originally Posted by 97tbird
Originally Posted by benjy
i do not own or want a DI only vehicle + believe the thinner oils that ONLY benefit mpg's a little are worse as their lightness MAY seep into the combustion chamber MORE than higher viscoty oils. in my experience using thicker at running temp oils + seeing less consumption points to that IMO. oils hot viscosity is measured @ 212 F + unless its a real synthetic PAO or Ester it continues to get even thinner causing more issues!!
It's interesting that this same car we have, has "thicker" oils recommended outside US. With 130k miles and no longer in warranty, the temptation to switch to a o/30 or 5/30 full syn is getting stronger
In ROW I'm thinking higher compression ratio and premium fuel required.
 
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Originally Posted by john_pifer
It's caused by the PCV and EGR systems. If you could deactivate EGR, and run catch cans, it likely wouldn't happen at all.
Skyactiv doesn't have an EGR valve. Not sure if that's a contributing factor to why these have so little build up or not, but it's worth noting the system isn't very typical.
 

JTK

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It ain't pretty, but it must not be a problem for this engine. With the lump of coal looking horror pics we've all seen online with some DI engines, you wonder what oil they used and the OCI and care in general those engines were given. The approach I'm taking with the DI engine in my 2019 Nissan Pathfinder is short OCIs. I've been doing old school 3000mi OCs with Supertech synthetic 5w30 as opposed to the 0w20 @ 5000mi Nissan suggests for this VQ35DD.
 
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Nashville, TN via Memphis
Originally Posted by RamFan
Originally Posted by john_pifer
It's caused by the PCV and EGR systems. If you could deactivate EGR, and run catch cans, it likely wouldn't happen at all.
Skyactiv doesn't have an EGR valve. Not sure if that's a contributing factor to why these have so little build up or not, but it's worth noting the system isn't very typical.
Interesting. Reckon how they're able to get the exhaust to pass emissions without EGR.
 
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Chicagoland
Originally Posted by john_pifer
Originally Posted by RamFan
Originally Posted by john_pifer
It's caused by the PCV and EGR systems. If you could deactivate EGR, and run catch cans, it likely wouldn't happen at all.
Skyactiv doesn't have an EGR valve. Not sure if that's a contributing factor to why these have so little build up or not, but it's worth noting the system isn't very typical.
Interesting. Reckon how they're able to get the exhaust to pass emissions without EGR.
Most likely through the variable valve timing system. By changing the timing, they can either push some exhaust back out through the intake valve to be sucked back in later, or by closing the exhaust a little early to keep some trapped in the cylinder.
 
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Originally Posted by john_pifer
It's caused by the PCV and EGR systems. If you could deactivate EGR, and run catch cans, it likely wouldn't happen at all.
Unfortunately, catch-cans don't stop the development of these deposits. There are countless examples of this shared on the various chat boards and even a recent "humblemechanic" video.
 
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Originally Posted by Skippy722
Originally Posted by john_pifer
Originally Posted by RamFan
Originally Posted by john_pifer
It's caused by the PCV and EGR systems. If you could deactivate EGR, and run catch cans, it likely wouldn't happen at all.
Skyactiv doesn't have an EGR valve. Not sure if that's a contributing factor to why these have so little build up or not, but it's worth noting the system isn't very typical.
Interesting. Reckon how they're able to get the exhaust to pass emissions without EGR.
Most likely through the variable valve timing system. By changing the timing, they can either push some exhaust back out through the intake valve to be sucked back in later, or by closing the exhaust a little early to keep some trapped in the cylinder.
They utilize a method called exhaust scavenging by using tuned headers. The explanation starts at the 2:56 mark. https://youtu.be/rNtS8qyjIJU
 
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Whatever they do, Mazda has had no widespread issues and are exceedingly well built engines. Quite possibly the best out there right now in the segments they represent.
 
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ON, Canada
Originally Posted by wemay
Whatever they do, Mazda has had no widespread issues and are exceedingly well built engines. Quite possibly the best out there right now in the segments they represent.
I tend to agree, my wife drives '15 CX-5. Speaking of DI 2.5L Skyactiv engine, at every image that I see, it looks like the injector has a chance to hit the valve still, at least by the far edge of the spray cone. With early injection and (perhaps) rotating valve, who knows...
 
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