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Interested in pics of what you find.

I’m at over 80k miles on my 2014 with 2.0L and still haven’t touched a thing but oil changes. Still runs like new with no issues.
Well I did it today. The DSLR wasn't any help, couldn't get enough light in there without blocking the view. I ended up using my old phone. So something at least.

I'm going to make a detailed post later tonight. I'm a little busy with my kid at the moment, so after he goes to bed.

The results were interesting, I will say that much.
 

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2016 Mazda3 79k miles
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Ok, I am stuck to the edge of my seat for this one. I just bought a 2016 with 79k miles from Hertz earlier today. I can only imagine the amount of abuse that car has been through so far, and after seeing this debate, I think the first buy is going to be some intake gaskets.. Are there any other gaskets that Ill need for this job along the way? How long/big of a job is this? Like a solid weekend, or just a busy afternoon?

I think before I do, though, I will check my mpg and see if there is any significant reduction.. but anyways, this is a very interesting debate! I am looking forward to some conclusions!
 

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Ok, I am stuck to the edge of my seat for this one. I just bought a 2016 with 79k miles from Hertz earlier today. I can only imagine the amount of abuse that car has been through so far, and after seeing this debate, I think the first buy is going to be some intake gaskets.. Are there any other gaskets that Ill need for this job along the way? How long/big of a job is this? Like a solid weekend, or just a busy afternoon?

I think before I do, though, I will check my mpg and see if there is any significant reduction.. but anyways, this is a very interesting debate! I am looking forward to some conclusions!
Are you planning to try and clean the valve carbon? An oil catch can doesn't require gaskets as all you do is splice into the PCV hose.

If you want to clean the valves and want new gaskets, you'll need the intake ones and the throttle body gasket. My experience is it is probably not necessary to replace them - I know I didn't have to. They are rubber seals a lot like o-rings. I keep a tube of RTV silicone on hand just in case I tear one.

Cleaning the valves is not something you can just jump into and do in an afternoon. It requires planning. Simply spraying them with cleaner won't do much of anything. You need to get some fine ground walnut shell for a sandblaster. You'll also need to rig up a special tool. Smaller tube inside a larger one. Idea is larger tube fits in the port and other end on a shop vac. Smaller tube you attach to your sand blaster. This way you can blast and suck at the same time. Wow that sounds so dirty.

I'll be doing this job to my 3 in a matter of days, just not sure when yet. I'll be posting pics when I can.

I managed to buy a 50lb bag of ground walnut shell :) anyone nearby need some?
 

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Here’s how my intake valves look after 100k miles. All in a days work but I remove throttle body/ intake manifold and scrub down each intake valve with a toothbrush. Installed an oil catch can. Car runs like brand new again.
 

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Apart from the aesthetics of having a clean back of inlet valve, can you give any actual evidence that your car is "better" or is "like brand new again"?

ie dyno results before/after or fuel consumption before/after ?
 

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Here’s how my intake valves look after 100k miles. All in a days work but I remove throttle body/ intake manifold and scrub down each intake valve with a toothbrush. Installed an oil catch can. Car runs like brand new again.
Thanks for posting this. Your valves look very much like mine, 130k kms. This shows a trend or at least starts to. I'll be cleaning mine on Monday and will report back with results.

Please monitor your fuel consumption and report back with any change!
 

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Apart from the aesthetics of having a clean back of inlet valve, can you give any actual evidence that your car is "better" or is "like brand new again"?

ie dyno results before/after or fuel consumption before/after ?
Unless to show a magnitude of change - which doesn't seem to be what you're asking - dyno results are pointless evidence. I think it would be interesting to see how much of a change cleaning the valves makes, but not many of us have easy access to a dyno.

The reality is there is significant carbon buildup on those valves and we know full well from a mountain of evidence that this has a negative impact on both performance and fuel economy. Don't take my word for it, there's plenty of articles on the internet regarding GDI valve carbon.

Asking for dyno results to prove it made a difference is like putting water on a fire and then asking for evidence that it put the fire out. We can clearly see there is carbon and that it is reducing air flow.

Again, I think it would be interesting to see before and after dyno results but that is asking a lot. I sincerely hope this individual reports back with any change in fuel consumption. When I clean my valves, I know I will.
 

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Unless to show a magnitude of change - which doesn't seem to be what you're asking - dyno results are pointless evidence. I think it would be interesting to see how much of a change cleaning the valves makes, but not many of us have easy access to a dyno.



The reality is there is significant carbon buildup on those valves and we know full well from a mountain of evidence that this has a negative impact on both performance and fuel economy. Don't take my word for it, there's plenty of articles on the internet regarding GDI valve carbon.



Asking for dyno results to prove it made a difference is like putting water on a fire and then asking for evidence that it put the fire out. We can clearly see there is carbon and that it is reducing air flow.



Again, I think it would be interesting to see before and after dyno results but that is asking a lot. I sincerely hope this individual reports back with any change in fuel consumption. When I clean my valves, I know I will.


This ^^

I recently took the car for a road trip from Cali to Vegas. Highway mile my car averaged 38mpg while going +80mph. City I’m getting 25.5mpg. I would say I’m a spirited driver as well. This is with catless header + tune.

Previously I was getting <25mpg highway and like 19mpg city. Not only did I have bad carbon build up. Inside the intake manifold had traces of oil about 10cc of it. No doubt that had an ill effect on gas mileage.
 

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Well, from what I see, those valves don't look that bad at all......especially after 81k miles.


Bad.....


Not so bad.....


I would not even worry about that little bit of build up.
 

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Discussion Starter #51
Moderate valve build up is enough to cause a disruption in intake air flow. Any turbulence/restriction at all will, without a doubt, impact air flow thus affecting power, efficiency, and ultimately reliability.
 

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This ^^

I recently took the car for a road trip from Cali to Vegas. Highway mile my car averaged 38mpg while going +80mph. City I’m getting 25.5mpg. I would say I’m a spirited driver as well. This is with catless header + tune.

Previously I was getting <25mpg highway and like 19mpg city. Not only did I have bad carbon build up. Inside the intake manifold had traces of oil about 10cc of it. No doubt that had an ill effect on gas mileage.
Wow! Mileage improving from 25mpg before cleaning to 38mpg after cleaning is absolutely astounding!

I've got almost 40000 miles on my 2.0 Mazda, almost all of it driving on the highway. I have a lifetime average of about 44mpg, and I have not observed any decline in mileage from new to now. So, I apparently do not have any significant carbon build up at this point.

By recording my mileage on the Fuelly site each fill-up, I'll easily spot any significant degradation as time goes on. That's the reason I bother to record fuel mileage: it keeps me informed of any problems that might develop that can affect fuel efficiency.

And if/when my mileage drops significantly like nostalgichero's did, I'll certainly get those valves checked as my first priority. But for me, so far, so good, without an oil catcher or valve cleaning.

I wonder if anyone has actually proven that the oil catcher makes any significant improvement in valve cleanliness and engine performance?
 

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Well, from what I see, those valves don't look that bad at all......especially after 81k miles.


Bad.....


Not so bad.....


I would not even worry about that little bit of build up.
I agree that they could be worse in comparison to other GDI engines. However, how can you say this isn't a problem? Sure, the car works fine but you have no basis for comparison here. This is nothing more than your opinion and assumption.

Any carbon on the valves reduces the cross sectional area available for air intake therefore reducing power and fuel economy. Period.

The question is how much of an effect does it have? If its 1% I personally don't care in the least. If its 10%, now we're talking some serious numbers.

Instead of talking about IF it is a problem, we should be discussing when is it worthwhile to do something about it. Collectively, we don't have the information to do that yet but that is exactly what we're (slowly) trying to figure out.

My valves look similar to yours, and similar milage. The plan is to clean them off tomorrow so I should be able to help answer this. Any change in power is subjective.... Not very good evidence but I should be able to tell IF there is a difference. Fuel economy will be easier with the aid of the onboard electronics. It'll just take time.
 

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Wow! Mileage improving from 25mpg before cleaning to 38mpg after cleaning is absolutely astounding!

I've got almost 40000 miles on my 2.0 Mazda, almost all of it driving on the highway. I have a lifetime average of about 44mpg, and I have not observed any decline in mileage from new to now. So, I apparently do not have any significant carbon build up at this point.

By recording my mileage on the Fuelly site each fill-up, I'll easily spot any significant degradation as time goes on. That's the reason I bother to record fuel mileage: it keeps me informed of any problems that might develop that can affect fuel efficiency.

And if/when my mileage drops significantly like nostalgichero's did, I'll certainly get those valves checked as my first priority. But for me, so far, so good, without an oil catcher or valve cleaning.

I wonder if anyone has actually proven that the oil catcher makes any significant improvement in valve cleanliness and engine performance?
I'm curious as to at what point it makes a difference. I notice my 3 eats WAY more fuel at higher speeds. All cars do, but this seems disproportionate. Between 90km/h and 120km/h we're talking over 1L/100km. That's pretty huge.

So I'm wondering if the carbon buildup has a minimal negative impact in the lower rpm range...just an idle theory really, I have nothing to back it up.

As far as catch cans go, supposedly they can help a little but do not solve the problem. There's very little evidence out there. We may have to do our own.
 

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Also, guys. You don't need to guess or take bad photos. A boroscope that plugs in to your phone is literally 35 dollars.

[ame]https://www.amazon.com/Depstech-Endoscope-Inspection-Megapixels-Smartphone/dp/B01MYTHWK4?[/ame]

Please, someone just buy one so we can put this to rest with actual good evidence lol.
 

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Also, guys. You don't need to guess or take bad photos. A boroscope that plugs in to your phone is literally 35 dollars.

https://www.amazon.com/Depstech-Endoscope-Inspection-Megapixels-Smartphone/dp/B01MYTHWK4?

Please, someone just buy one so we can put this to rest with actual good evidence lol.
So let's get this straight...my eyes and a flashlight work quite well for this job. I actually have a scope but can't capture images since its an older model with a screen. I tried using my DSLR camera with a macro lens but was unable to get enough light in there and the same time. Like a few others, I was good enough to use what I had on hand - my old phone. The light makes for good images since its next to the lens. I admit the photos aren't great, but I can clearly see what is going on well enough.

Considering all this, you'd like myself or another one of us taking the time out of our lives to investigate this and post images to buy another tool for the sole purpose of giving you better images....

I just spent my afternoon in the heat working on this exact job blasting my valves with walnut shell. Unless you're buying me the scope, I know where you can stick it good sir.
 

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2016 Mazda3 79k miles
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@zero_gravity, thank you for the info.

I have been checking my first tank of gas in my new 3, 79k, and I am getting 40+ highway, and roughly 28 city. I have been feathering it the whole time though, which is not how I normally drive. I wanted to test this as a good baseline for my next tank, which I will drive like .. usual.. but it doesnt seem I have any issue yet. I didnt really realize this was that big of an issue, and evidence is needed.. I will take some pics of my mpg app next time to show.
 

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You can't accurately gauge usage from 1 tank to another. You need to do 1000miles then compare the next 1000miles.

Too many other variables,

How do you measure your usage?
 

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How does the dealership's fuel induction cleaning (chemicals) work compared to this physical disassembly and scrubbing you folks are doing?
 

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How does the dealership's fuel induction cleaning (chemicals) work compared to this physical disassembly and scrubbing you folks are doing?
Simply put, it doesn't. The fuel does not touch the intake valves, period. Their chemicals are no better than putting injector cleaner in your fuel tank. Even that, by the way, is fairly useless as well. If the fuel full of cleaners isn't hitting the valves how would it clean them?

Unless you live in an area with substandard fuel, the pump gas already has detergents in it. You can put more in but what's the point? Its a lot like putting extra detergent in your washing machine when your clothes are already coming out clean.

Search Google for top tier fuel. This is not premium fuel.
 
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