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Discussion Starter #1
Given that our cars use direct injection (DI) it is a known fact that the engine is prone to increased accumulation of deposits on the valves as a result of deposit forming substances being fed back into the engine via the PCV system. Since there is no fuel being sprayed directly over the valves, like it would in a port injection setup, this requires us to take special precautions to slow down the build up. From my research I have found some information and would like others' input.

1) OIL CATCH CAN: The basic idea here is to filter as much oil vapour as we can before it is fed back into the intake manifold. How effective is this and has anyone had this installed on their Sonata? If so how much did it cost for parts and labor? Also is this an aftermarket or OEM part?

2) OIL WITH LOW NOACK VOLATILITY: The basic idea here is to use an oil that is less likely to vapourize or burn off. How effective is this and can someone recommend some conventional/Dino oils with low NOACK volatility? I came across Pennzoil yellow bottle (conventional) as being one of those. However I know that Hyundai seems to recommend Quaker State in the owners manual (not sure why).

3) CLEANERS: Fuel injector cleaners won't help since they will never make it to the valves in a DI engine. However there is the idea of running Seafoam through the brake booster or air intake. BP also has a direct injection fuel system cleaner which I'm guessing must be run through the intake as well. How effective is this and how often should one do this?

4) PHYSICALLY CLEAN VALVES: This is when you have gotten to the point where you have to physically clean the valves by taking everything apart. This is the last resort.

Can someone also comment on how prone Hyundai DI engines are as opposed to other manufacturers?
 

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Sonata has used GDI since mid-2010. No carbon buildup problems that I know of. The biggest issue is fuel dilution, so change your oil more often than the recommended 7,500 miles. Personally I go about 4k between changes with 5w-30 (1.6T and 2.0T should be using 5w-40).
 

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Discussion Starter #4
From what I've read that's a thing of the past. Hyundai uses valve timing to keep the valve open during fuel injection in turn getting mist on the valve. Enough that it's not a problem now.
Could you cite your source? I find this approach interesting. I know Toyota deals with this problem by have a dual injection setup where port injection is used under light load and direct injection is used under heavy load.
 

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The best thing you can do is use a top tier gas instead of the cheap stuff at Circle K, Safeway, Fry's, etc. Here is a list of retailers:
Top Tier Gasoline
I've had to settle for Chevron gas because I can't find any Aloha gas stations. :bwekk:

Getting serious, Hyundai GDI engines don't use EGR technology which lessens intake valve carbon buildup. There are also some products, other than Seafoam or BP, specifically designed to be sprayed into the throttle body to remove some of the intake carbon build up. For instance, there's the CRC GDI Intake Valve Cleaner that you spray into the engine through the throttle bottle after you remove the air intake hose. (I'm not affiliated in any way with CRC Industries)

GDI IVD? Intake Valve Cleaner, 11 Wt Oz - Product Information
 

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Discussion Starter #8
The best thing you can do is use a top tier gas instead of the cheap stuff at Circle K, Safeway, Fry's, etc. Here is a list of retailers:


Top Tier Gasoline
I know that Hyundai recommends this but I can't seem to understand the basis of this. Of course top tier gas will give you better performance but doesn't solve the fundamental issue where gasoline doesn't even get sprayed over the valves in the first place to clean the valves. This is the same reason why I mentioned fuel injector cleaner added to the gasoline tank never makes its way onto the valves either.
 

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I've had to settle for Chevron gas because I can't find any Aloha gas stations. :bwekk:

Getting serious, Hyundai GDI engines don't use EGR technology which lessens intake valve carbon buildup. There are also some products, other than Seafoam or BP, specifically designed to be sprayed into the throttle body to remove some of the intake carbon build up. For instance, there's the CRC GDI Intake Valve Cleaner that you spray into the engine through the throttle bottle after you remove the air intake hose. (I'm not affiliated in any way with CRC Industries)

GDI IVD? Intake Valve Cleaner, 11 Wt Oz - Product Information
Where did you come across this information that Hyundai GDI's don't use EGR technology? I thought it was required by law to reduce NOx emissions?
 

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We have been discussing this for a while on the YF section


This is being added today to the YF section.


Considerations on Carbon Deposit Formation in Gasoline Direct Injection Engine Paper
They used a Hyundai Motor Company Theta II GDI (2.4L)
It has a few pictures.

http://www.pecj.or.jp/japanese/overseas/conference/pdf/conference12-19.pdf

GS Caltex is a South Korean oil refiner. The company changed its name from LG-Caltex Oil Corporation to GS Caltex Corporation on January 27, 2006. It is jointly owned by Chevron and GS Group.
GS Caltex was founded in May 1967 as the first private oil company in Korea.[citation needed] GS Caltex provides more than one-third of Korea’s oil needs and exports over 50% of its products.

GS Caltex - Wikipedia, the free encyclopedia
 

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Where did you come across this information that Hyundai GDI's don't use EGR technology? I thought it was required by law to reduce NOx emissions?
hyundai, among other other manufacturers have stopped using EGR for emissions for quite sometime now.

The reduction of NOx is still done using exhaust gases, however it is done within the combustion chamber. Valve overlap is changed via the cvvt action, and causes a specific amount of exhaust gas to stay in the cylinder. This reduces temps, as the gas is basically inert.

 

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is that only theta 2 or all hyundai GDI engines had stopped using EGR? becoz I wanted to buy a KIA rio and so far people are just talking about theta 2....
 

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is that only theta 2 or all hyundai GDI engines had stopped using EGR? becoz I wanted to buy a KIA rio and so far people are just talking about theta 2....
00000732 Welcome to the forums. Please update your profile. Easy to do. Click on "CP user" in upper right of screen (on smartphone use PC mode). That will take you to a page where you can click on the "Edit Profile" link on the left side of the screen. You should update the year, model, and engine of your vehicle. Also, please include your general location city/area, state, and country. We have members all over the world. Different countries may have differences in models and laws/regulations. THANKS!!!
 

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Hmmmm.

This is interesting

"Positive crankcase ventilation(Blow-by) was not related to carbon deposit formation"

So all these catch can gurus are wasting their money.
 

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Hmmmm.

This is interesting

"Positive crankcase ventilation(Blow-by) was not related to carbon deposit formation"

So all these catch can gurus are wasting their money.[/QUOTE]

I would not say that.I have no idea in percentage terms what an oil catch can catches,but,I do have proof that a catch can works to some extent. There is a thread in the YF section where members have posted the oil/gunk they have contained and prevented from going back into the intake and into the motor.Its really some nasty looking stuff.

The pic below is between oil changes.Without going into my log, I forget the exact measurements or the miles for the amount shown,but,it surely will help.

Does anyone with a 2015 have an OCC installed?

.
 

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Catch cans do prevent gunk build up on the intake valves. When the oil and other fluids mix with the intake air they can carbonize on the intake valve- which makes perfect sense despite what that says. Also, the head ventilation system has to be run through a catch can as well as the PCV. All that gunk lowers the effective octane of the fuel everytime the engine takes a gulp of it.

Water/meth injection systems also reduce intake valve deposits and with a tune create a lot more engine power.
 

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I would not connect fuel burn to carbon deposits on intake valves because
I DO BELIEVE that this is oil burn that contributes to carbon deposits.
 

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Makes you wonder why Hyundai wouldn't add such a simple thing as a catch can to its engine design. Is it purely cost saving, or have engineers somewhere considered this and rejected the idea?
 

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I have a 2015 sonata that is NOT have a turbo. I've had an engine knock since about day one. Last month the dealer tried to correct this for the 4th time. They took the head off and sent it to a machine shop to be cleaned as well as cleaning the valves while the head was offf. They said they took more carbon out of my engine than they've ever seen. I haven't missed anything on my maintenance schedule and it's all been done at the dealer. They had my car for about 3 weeks and put 30 man hours into it. I've had my car back for not even a month and the knock is back already.
 
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