Carbon Build up with Direct injection Engine in the CX5

That dude lives in Indonesia and admits that he never gets above 40 km/hr and is constantly in stop and go traffic. Engine never has a chance to keep the intake valves clean. Hear the traffic in the background during that video? Worst case scenario imo.

Read up at the following forum: https://www.mazdas247.com/forum/showthread.php?123864255-Oil-Carbon-build-up-palooza!/page5

I wont be doing anything to the intake on my car as it runs fine: no drop in performance or mileage since new (mine is a 2013 approaching 63k miles), and my drive is primarily 70 mph for 20 miles each way with rpms above 2500. Maybe Ill clean them at 100k miles if I feel so inclined. Dont want to fix what isnt broken but youll get differing opinions on it.
 
Full disclosure: I am not an expert nor an engineer - I am just an average guy who likes to research these things. I had a similar concern as you and went all around the mulberry bush regarding this issue.

In the end, to keep things relatively clean I use only top tier gas (Shell, BP, Costco, etc...) and once a week take it out for a long / high rev'ing or "spirited" driving session. It is my understanding that Mazda has accounted for carbon build up in their designs (I think something to do with better seals and shape of the piston?) and discourages any kind of spray cleaning agent.

Just my two cents.
 
I remember reading somewhere they purposefully designed the intake and cooling system in such a way that temps in the intake remain above the temperature at which carbon buildup can form. Obviously, the guy who made the YouTube video doesnt operate his CX5 in a way that gets temperatures high enough.
 
106k miles, no change in performance, I use whatever gas I want.

Yea, exactly.

Here we go again...

Just drive the thing, put it through it's paces at least every gas tank once or twice, and don't worry about a thing. Enjoy...
 
No issues here. Been meaning to do a carbon cleaning myself via removing intake valve....just too lazy and no reason to (no performance loss) on 99k mile engine and 53k mile engine.
 
No issues here. Been meaning to do a carbon cleaning myself via removing intake valve....just too lazy and no reason to (no performance loss) on 99k mile engine and 53k mile engine.
Hope you can find time to do at least one of your SA-G engines, especially the higher-mileage one. Chris_Top_Her once removed his intake and found pretty bad carbon build-up on his CX-5 if I remember it correctly. Hence he put a catch can after that. He's an airplane pilot and we all know he's a spirited driver.


It seems whoever took the intake out by need or curiosity all found pretty bad carbon build-up on their CX-5 even with low miles.
 
48,000 miles on my 2014 CX5 and it runs better than new I think. I use 87 octane Shell fuel, PP oil & WIX OIL FILTERS EVERY 6,000 MILES. Ops sorry about the caps. Darn cap key is in the way of my big hand. Possibly we can get overly concerned about a problem that isn't a problem in the real world? Ed
 
Why are you worried or even considering a service to remove carbon build up?
Just a guess re: cost of service, but given the amount of time to remove the intake and do the cleaning: ~$500
I like a clean and leak free engine as much as anyone. But once you start disassembling the engine expect to find oil inside the intake - a fact for every engine design since PCV valves sent excess crankcase vapor back into the intake (30+ years or more?).
But what is "bad" carbon build up? That should be defined by impact on engine performance.
So - I've got to disagree with several of the posts here - including the excellent YouTube video: The amount of carbon build up that is shown is not enough to cause performance issues.
Was there a problem before the cleaning? Maybe I missed that part of the story - but it seems like people have pulled the intake and are aghast with the oil and carbon build up they see. But, based on what I saw in the video, there is lack of experience that would provide a reference for comparison. A review of the YouTube video: The oil in the intake manifold and in the runners in the cylinder head leading to the intake valves is completely normal. 100 miles after re-assembly it will look the same and have 0 impact on performance. The amount of carbon on top of the valves, also was not enough to restrict airflow and was still soft enough to be easily removed with a toothbrush and solvent.
Hopefully everyone is educated enough about direct gas injection to know that the gas and oil have no impact on the amount of carbon that builds up on the top of the intake valves.
Adding an oil catch can system will theoretically have some impact by removing some of the oil in the crankcase vapors that are recycled into the intake. But, there is no way to prove an oil catch can is necessary or even to quantify how long you will delay valve cleaning. And, a bit of irony is that the compulsion that leads to installing a catch can is likely to result in that same owner pulling the intake and cleaning the tops of the valves as part of preventative maintenance.
 
YouTube author claims smoother idle and improved throttle response after cleaning. I only see one post here so far suggesting intake cleaning, majority so far including myself dont think its necessary in most cases.
 
You should be more concerned about the transmission than oil build up. once its past 75-100 k you can get it cleaned.
 
Of the now hundreds of thousands of these engines on the road I've only seen a handful of reports about this and they've all involved atypical use or environments.

I'd be curious at the 200,000 mile mark what an engine looks like. Maybe there'd be enough time for some buildup there.
 
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That did not look bad at all. Maybe I skimmed the wrong parts of the video, but I couldn't see any obstruction, just a thin layer of carbon build up. Nobody should expect it to look clean in there.
 
If you use top tier or a gas with detergent, which is pretty much all gas stations and use synthetic oil and change it regularly the motor will stay like new clean. Mazda's injector pattern cleans as well as cools the combustion chamber with jets of fuel instead of a mist, as you can see in this video:

https://www.youtube.com/watch?v=fDFgiLrEX1o

Also it is important to get the engine to normal operating temperature.
 
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That isnt actually fully true. Since the injector is in the cylinder and not the intake, the intake tract will never get clean. Some manufacturers are adding injectors into the intake track as secondary but mostly for cleaning the intake valves and the intake tracts.
 
That cylinder deactivation video is interesting, or 2018 GT has it, but if it shuts the intake AND exhaust valves, isnt there a compression issue?
 
if what is in the video is right and I dont know, there is a 3rd spray in the valve before it retracts. Also I read somewhere its kept open more to help with the knocking and high compression.
If all that is true, I dont see major issues with carbon on valve.
Of course except if you drive your car,for 2 miles only and it never reaches normal operating conditions.
 
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