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.

 

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).

 

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

 

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

 

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

 

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!!!

 

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.

 

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?

.

 

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.

 

I make my Hiunday accent 2012 turbo but my air/fuel mix is poor I buy whater/methanol but I need to set that to make my mix rich or make my direct inyection programmable

 

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.

 

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?

 

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.

 

How many miles? ,Its hard to believe that carbon would be an issue in a years time on a 2015. Sounds fishy to me,did they show you the what all this carbon looked like on the head? What exactly did they do the first three times to your car? Where is the knock coming from?

 

The first treatment wasTechron, which did nothing. They also had me switch where I was getting gas which was chevron. The second time they kept it for a few days and ran more injector cleaners through it and it did nothing. Third time they used a treatment that had to sit in my engine for a day and that did nothing so they finally removed the head and sent it to a machine shop. They had it for 3 weeks and it seemed to fix it. But it's knocking again. I don't remember the exact mileage of when it began but it was about 3 months after I bought the car. So just a couple thousand miles. They finally removed the head at 27000. It pisses me of because the whole time they were saying they never heard of this problem then later I researched that they lost a class action lawsuit on their gdi engines for the older model. So I know he knew they were an issue. I'm calling tomorrow to tell the dealer the knock is back. I don't understand why they tried injector cleaners on a direct injection engine.

 

The knock is an engine knock. It's misfiring due to the build up

 

Here's the work order from when they took the head off

 

Try to use higher octane number gas (89 or 91) and switch to 5w30 full synthetic motor oil.

 

Strange to have that problem so soon and frequently. Something is amiss. 7 months and 8000 miles now on my 2015 2.0T and zero issues. Shell or QT 93 octane at every fill up, I added 2 bottles of Techron at 3500 miles and a couple of days ago, and Penzoil Platinum 5W30 at 945, 3500 and 6800 miles.

 

Unfortunately it sounds like they corrected the symptom and not the cause. I have not heard of this being a common problem. My 2015 2.0T has 47,000 kms (~29,000 miles) on it and I have not had any problems. I use top tier gas but just regular 87 octane and have never used any additives. It runs great and delivers good fuel economy.

 

I'd guess oil blow-by or a pcv issue if carbon is building up quickly and significantly. I'd say an oil consumption test is in order at the very least.

 

Higher octane gas for actual knock.
Thicker full synthetic oil to prevent oil blow-by and to better handle the stress of gdi engine in general.

 

I hope they get it straightened out for you,I know its very frustrating having a new car and issues like this. Why did they change the injectors? I suspect your fuel mileage had been kind of lousy leading up to this?

 

my dealer uses BG products
the induction service is a good one

I use their oil flush often.
I do an oil change with cheapo oil
add BG oil flush stuff (I forget the name)
run time and rpms as instructed
drain cheapo oil (now black)
change filter and put in synthetic
---
its amazing how fast new oil can go black with this stuff
I am impressed
they recently changed the product line and i forget the name of the engine kit

 

I have used BG products before they are very potent if you notice BG products have there own part number. that's how you can tell from the cheap over the counter stuff. to the Professional grade stuff.

 

I have a 2017 Sonata. I have been using 98 Octane and had the oil changed religiously every 5000 kms (3,107 mi). I'm already approaching 20,000 kms (12,430 mi) and had been driving 90% highway speeds of 135 kph (84 mph), 2,700 rpm on 50 kms (31 mi) each way. Recently, I have observed a noticeable drop in performance especially during acceleration and during cruising speed. I now have to step on the accelerator much harder than when the vehicle was new. I have not driven the vehicle more than 155 kph (96 mph) nor 4,000 rpm.



I suspect it might have something to do with carbon build-up and that the build-up has created a gap between the valves and the air intake causing some of the combustion to leak. I also cleaned the intake air filter and it only made almost no difference.



I cannot believe that I am already facing this problem with about 85% of the loan left unpaid.


Has anyone used CRC GDI IVD Cleaner? How was it? Did it improve performance?


Can somebody post a video on how to do it on Hyundai Sonata 2017 or on engines with the same configuration?

 

You seem to take very good care of your car and yet the issue still occurs. Man, it's like a roll of the dice. Is Hyundai worth it?

 

Thats exactly what I been thinking with hyunfai its a roll of the dice. I too am facing very bad gas milage amoung other issues with a car I just bought with 90% loan left to pay. Will never buy another hyundai again. Back to Toyota and Honda.

 

I have a can waiting for my next oil change. I believe it's a two person job as you need to keep the RPMs at 2K while spraying into the intake (after the air filter) or directly into the throttle body.... based on the directions on the can.

I have 20K on my car, and haven't noticed much difference in the car yet, but I'll do the best I can and just hoping to get 100K miles.

FYI: The price of the product is locally cheaper over amazon.

 

I do it by myself. a stick or cane wedged between the seat and console will hold accelerator at 2000 rpm and then it can be injected by extending the straw on the can with 10" of drip line tubing and remove the air filter and insert the tubing into the intake hose or remove the vacuum line directly into the intake manifold and inject there or loosen the intake hose at the air filter box and slip the straw between the box and the intake hose. if you inject it before the turbo CRC claims it will also help keep turbo clean (pictures on their site)

 

This thread has been covering this topic for a while
http://www.hyundai-forums.com/lf-2015-sonata-i45/627026-2015-2-4l-intake-valve-cleaning-how.html

I have a post in it about CRC GDI Intake Cleaner and how Ive been using it. It is an easy 15 min job and then let car sit and heat soak for 1 hr and take it out at freeway speeds (I do a few 10-80mph runs, foot to the floor) to blow out any residual cleaner and carbon. Do it before an oil change. The BG GDI Via service is a very good intake cleaner but usually runs about $ 150. For the cost difference (CRC $10-15 a can) Im hoping that routine use of the CRC cleaner every 10000- 15000 miles and using synthetic oil changed at 5000 miles ( intake valve carbon buildup is generally due to no fuel passing over the valves in a direct injection engine to clean them like in a port injected engine so the recycled crankcase gases containing oil deposit on the valve) I also use top tier fuel and occasional BG44k or Techron in the tank to keep injectors clean and fuel system clean.

The CRC website has before and after pictures of the Hyundai /Kia intake valves and piston, Injectors before and after treatment.

Its interesting to me that this is a common problem with all DI engines and yet in our service manual they do not address any maintenance for this. They recommend top tier fuel and/or Fuel additive but that does nothing for the intake valves

 

"I suspect it might have something to do with carbon build-up"

At 13K miles and your driving habits, extremely unlikely. Would be worth a trip to the dealer to check it out. I have a 2.0L GDI that had a GDI cleaning at 45K with no change in performance. Thought a rough idle was indicating valve build up, but not.