Skyactiv Intake Valve Deposits - Photos

buster

buster

Joined
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I can't recall if I already posted/shared this. This is from the Mazda 3 forum. I'd love to know if using Valvoline Modern Engine would have made a difference.

"so here we go...

PURPOSE: when mazda designed and started manufacturing the skyactiv-g engine that is in all of our 3rd gen cars, they decided to use direct injection. as we all know, no fuel hits the back of the valves with this design. many manufacturers have had problems with buildup of carbon on the intake valves causing loss of power and fuel economy. mazda was very clear that their design would allow the valves to run much hotter and prevent buildup of problematic carbon. the purpose of this is to try and determine if that is true or not. i think you'll find the results interesting.
ABOUT MY CAR:
- 2015 mazda 3, built in mexico
- i purchased new, original owner
- 2.0L skyactiv-g, manual transmission
- mileage at the time the images were taken is 130,470 km
HOW IT IS MAINTAINED:
i perform ALL of my own maintenance and have since day one. as per the owner's manual, oil changes are every 8000 km. this is the schedule specific to canada and i have adhered to it strictly in both distance driven and time. in fact, i tend to do my maintenance a little early since i do not want to go over. i use castrol edge 0W-20 and ONLY this oil. it is considered a synthetic oil. i also use the OEM oil filters from the dealer. the filter is changed at EVERY oil change.

in short, i take good care of my cars. why castrol? i can get it cheap and it's easy to get here. it is specifically recommended in the owner's manual.

all other regular maintenance items are kept up to date with just as much rigor. air filter, regular checks, etc.

injector cleaners, engine shampoos, seafoam and other such snake oil is NOT used. EVER! your fuel already has detergents in it, so i consider it unnecessary and potentially harmful. if your clothes come out of your washing machine clean, adding more soap isn't going to do any good...

HOW IT IS DRIVEN:
i generally drive 20km/h over the speed limit on highways and 10km/h over in the city. conditions permitting of course. i commute to work, my drive is 95 km (yes i googled it). drive time is about an hour. most of my use is highway, but i do some city driving where i live. there are a good deal of hills on my drive and the city i live in is built in a big valley. i tend to accelerate fairly hard, but i'm not completely insane on the road. we'll say 'spirited' as mazda puts it. normally, i'd say my engine doesn't see much beyond 4000 rpm too often. i use cruise control often.

this car is driven in ontario, canada. as such, it sees temperatures over 30ºC and under -30ºC. we see all extremes here. i use a block heater in the winter to help it out. winter time i have a set of winter tires which negatively impact fuel economy.

FUEL:
i usually fuel up at the Esso around the corner which is considered a 'top tier' fuel station. i put regular 87 octane in as the more expensive grades doesn't do a thing for this car.

MODIFICATIONS: none. completely stock. not even an oil catch can.

SYMPTOMS: none that i can detect. i suspect i've lost a little power and fuel economy since it was new, but nothing too significant. this is purely exploratory. my car does not burn oil - at all. typical fuel economy is roughly 600km per tank. works out to somewhere around 6-7 L/100km. do note that speed has a HUGE impact on the fuel economy in this car. if i drive slow (the limit) i can drop the fuel economy under 6L/100km easy. especially if it's an 80km/h highway. all the hills i drive have an effect. i try to coast in gear to take advantage of the deceleration fuel cutoff as much as reasonably possible. fuel economy isn't so great in the winter as expected.

in short, i am probably in the best position to look for carbon. regular boring joe driving with nothing that could potentially upset the results.

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My wife had a 2012 Mazda3 with a 2.0L Skyactiv engine hence my username. Many vehicles tend to get better fuel economy when the engine breaks in, but her Mazda was the opposite. It got it's best mileage brand new and slowly got less as more miles were put on.
A new air filter didn't help and it still had the original Bridgestones on the car as the gas mileage dropped. I assume deposits were the reason.
 
This amount of buildup in port injection engine will cause engine performance problems because the carbon buildup will absorb the income fuel charge. But how serious is this buildup on a DI engine? Since no fuel is sprayed in the intake port and doesn't come into contact with the valve, I think it would take a lot more carbon buildup than that to cause issues with the intake air charge velocity. As long as the valve seat is kept clear of carbon and debris I think this amount of carbon buildup is normal and likely never cause an issue.
 
Originally Posted by skyactiv
My wife had a 2012 Mazda3 with a 2.0L Skyactiv engine hence my username. Many vehicles tend to get better fuel economy when the engine breaks in, but her Mazda was the opposite. It got it's best mileage brand new and slowly got less as more miles were put on.
A new air filter didn't help and it still had the original Bridgestones on the car as the gas mileage dropped. I assume deposits were the reason.


Most likely. I drive my car a lot like this guy.

My car sees daily highway drives and at least one redline a day. I usually keep my cars for 5 years which is around when this probable starts to reveal itself.
 
Originally Posted by buddylpal
This amount of buildup in port injection engine will cause engine performance problems because the carbon buildup will absorb the income fuel charge. But how serious is this buildup on a DI engine? Since no fuel is sprayed in the intake port and doesn't come into contact with the valve, I think it would take a lot more carbon buildup than that to cause issues with the intake air charge velocity. As long as the valve seat is kept clear of carbon and debris I think this amount of carbon buildup is normal and likely never cause an issue.


I can tell you that Skyactiv engines run a long time with few issues. Many hit 150K + with no issues at all. I think it often looks worse than it really is in terms of performance impact.
 
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.gif
. It's hard to know how effective they really are.
 
OP, good write up.

Every direct injection application gets Intake Valve Deposits. How this translates into drivability issues is a toss-up vehicle to vehicle. In my opinion, not worth worrying about.
 
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Interesting.
My wife's car is a 2014 Mazda6 - dealer maintained so far with 130k miles or so. It has the 2.5L SkyActiv-G. It's a daily driver, and gets driven almost every day. 3-4 times a year long trips of about 400 miles round-trip.
Using 0w-20 Mazda oil (syn) (idemitsu?) at the dealer for oil changes every 7,500 miles.
We always use top-tier gas (Shell and BP mainly). MPG has seen no change and remains close to or same as when it was new. No fuel / oil additives used.

No mechanical / performance problems that we have noticed and car still runs like new. It does see slightly more hwy (65 - 70 mph) miles than city.

How does one take those pics? Would love to know the state of our car's intake valves....
 
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"HOW THE IMAGES WERE TAKEN: my original plan was to use my DSLR camera. canon T5i with a tamron 90mm f2.8 macro lens. the problem is that there's not enough room to get light in there and the lens at a good angle. it's just too deep in. i'd need a ring flash that fits on the end of the lens and that's one of the few camera goodies i just don't have. so instead you get my cruddy cell phone pics. i have a 5 year old HTC M8, 4MP camera. sorry guys, but it's better than nothing. the images have been cropped to get just what we're interested in. this is original resolution."
 
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!!
 
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
 
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Originally Posted by buster
"HOW THE IMAGES WERE TAKEN: my original plan was to use my DSLR camera. canon T5i with a tamron 90mm f2.8 macro lens. the problem is that there's not enough room to get light in there and the lens at a good angle. it's just too deep in. i'd need a ring flash that fits on the end of the lens and that's one of the few camera goodies i just don't have. so instead you get my cruddy cell phone pics. i have a 5 year old HTC M8, 4MP camera. sorry guys, but it's better than nothing. the images have been cropped to get just what we're interested in. this is original resolution."

Thanks - i didn't have any prob's with quality of pics. They're nice.,
I meant what do i have to do to get a pic as in, remove valve covers at the least?
 
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.
 
Originally Posted by buster
"HOW THE IMAGES WERE TAKEN: my original plan was to use my DSLR camera. canon T5i with a tamron 90mm f2.8 macro lens. the problem is that there's not enough room to get light in there and the lens at a good angle. it's just too deep in. i'd need a ring flash that fits on the end of the lens and that's one of the few camera goodies i just don't have. so instead you get my cruddy cell phone pics. i have a 5 year old HTC M8, 4MP camera. sorry guys, but it's better than nothing. the images have been cropped to get just what we're interested in. this is original resolution."


The clarity of the pictures were enough to give me initial impressions and further reservation about DI. I'm in the market now and so many vehicles are 4 cylinder 2.0 DI Turbo where I seemed biased towards the non-turbo 2.0 with the multi port injection found in the Toyotas and Lexus knowing much less HP.

With the f2.8, you should be able to open aperture wide open to 2.8, ISO at 1200+. and shutter speed ~1/10sec or even slower to get the picture to show the fine detail. Or maybe force it to flash with the manual flash button that's on the front of the camera. Not telling you what to do, but the gear you listed seems quite capable.
 
I recall seeing similarly NEGLIGIBLE amounts of deposits posted by a WRX owner over on NASIOC some time ago and some were making a big deal about it.

I see these pictures as being noteworthy for how CLEAN they are, not how dirty they are, compared to other, older DI designs (not PI, obviously)
 
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