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Question about carbon buildup on intake valves - 1.6 DI

40K views 97 replies 30 participants last post by  Rock the Box 
#1 · (Edited)
I just bought a new Soul Base 1.6 with automatic and love it so far (1 week and 200 miles). Very comfortable and versatile, and so far getting about 29MPG on the trip computer in mixed stop-and-go and hilly 2-lane roads while trying to vary engine speed for proper break in.

One question I have, though, is about possible carbon buildup on the intake valves. Since DI injects the fuel directly into the cylinder, regular fuel cleaners do not pass over the outside face of the intake valves, meaning they don't get the cleaning effect. Now the only thing passing by the intake valves is fresh air and the oil fumes from the PCV. From what I've read at many sources, the oil fumes can cause deposits to build up over time. This requires an engine disassembly in the worst-case scenarios in higher mileage vehicles.

However, I was wondering if Kia engineers had taken proper steps to ensure oil droplets do not re-enter the intake tract. I have seen aftermarket "catch cans" with internal screens and baffling to catch oil particles but am afraid of voiding the warranty. So, my thought is to switch to synthetic oil after the break-in period (probably between 5K and 10 miles). Synthetics should have fewer (if any) hydrocarbon emissions caused by heat, so I'm thinking less fumes = less deposits in the intake tract.

** THIS IS NOT MEANT TO BE ANOTHER 'WHAT BRAND OF OIL IS BEST' RANT ** Simply, I would like thoughts on whether 1) there is a history of intake deposits problems with the Kia 1.6 DI and 2) if using pure synthetic (100% synthetic - not blended or using petroleum base) would reduce the PCV emissions.

Thanks!
 
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#2 ·
First, Kia recommends the use of "top tier" gasoline to minimize carbon buildup, particularly in the 1.6 mill. Just google (or bing, or chrome) "top tier gas" to find out who sells it it your area. Don't know about the catch cans, but switching to synthetic will be a plus all the way around for your engine at the very least.
 
#3 ·
Use top tier fuel only. Look them up online, there is a list. ( Shell, Chevron, Exxon etc.. ). And every oil change, put in a bottle of Chevron Techron fuel system cleaner. You don't have too if using Top Tier fuel but it doesn't hurt it as Kia clearly states thats what they use and they approve it. Do that and you will never have a problem.
 
#6 ·
Use top tier fuel only. Look them up online, there is a list. ( Shell, Chevron, Exxon etc.. ). And every oil change, put in a bottle of Chevron Techron fuel system cleaner. You don't have too if using Top Tier fuel but it doesn't hurt it as Kia clearly states that's what they use and they approve it. Do that and you will never have a problem.
The Kia Soul engine certainly Ain't yo daddy's Chevrolet. :laughonfloor

Our little engines are just about the most High Tech engines ever put in family cars.
For instance, they are: DOHC, DFI, VVT, with "Igniters" for every spark plug, which in themselves are very High Tech.

I sometimes feel like I'm driving a car that was reverse engineered from an Alien Space Ship. :big grin:

As I understand the Fuel Injector problem, it's carbon buildup around the injector itself, not on the valves.
The Top Tier gasolines are supposed to have additives (detergents) that will either prevent this carbon buildup or clean it away. But how many of us can absolutely guarantee that we will only use Top Tier gas.
I try, but I can't guarantee it. So, I just do what Kia recommends and put in a small bottle of "Techron" additive, in my gas tank, with every oil change. (3k)
The smallest bottle, and also the cheapest, is the one that will treat up to 15 gallons of gas.

Buy Chevron Techron Concentrate Fuel System Cleaner (12 oz.) 67740 at Advance Auto Parts

It's a small thing to do, to keep our great little cars running at peak performance. Eh?

TM :cool:
 
#4 · (Edited)
Thanks for the replies. I understand about using Top Tier gas and additives to keep the injectors clean. My concern is the outer face (away from the cylinder) and stem of the intake valves, which are "upstream" and therefore do not benefit from the fuel or additives.
 
#13 · (Edited)
Just a repost of mountain_soul's link that explains the problem better than I did, and also explains why gasoline and additives don't really matter much in regards to the intake valves in the case of DI. Please read. Thanks.

Direct Injection Fouls Some Early Adopters - AutoObserver
 
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#14 ·
I too buy Wal-Mart (Murphy) gas, and Race Track Gas, and Pure Gas and whatever is the cheapest on the strip at the time I need fuel. Except for some additives, it's all Barge Gas anyway.

That's not to say that I never buy Top Tier Gas, because I do, but just not always. I have CC's for all the Top Tier stations close to my home.

But just for safety, and since Kia recommends it, I do use Techron fuel system additive. (at least once, per oil change)
It's a small thing to do for my precious little Gertrude.
She takes good care of me and I do my best to take good care of her.

I also use the Worlds Most Expensive oil additive, which helps my little 1.6 run smoother, cooler and longer with a higher level of performance. But that's food for another thread.

Cheers Mates!
TechnoMage :cool:
 
#15 ·
It may all be "barge gas", but the difference is in the additives that are added to the gas as it's being loaded into the tanker trucks for delivery to the stations. Each brand has it's own ratios and types of additives, so just because the trucks all load form the same fuel terminal in a given area doesn't mean that it's all the same fuel. I had one fuel hauler explain to me one time how he would put a bit more of the cleaner additives in the fuel that was going to stations where he would be treated better while delivering than he did where he was treated like dirt.
 
#16 ·
I've been doing some reading on GDI engines in general and it appears they have a problem with carbon build up on the intake valves resulting in poor operation upon startup from the design my worry (I just got a 2013 1.6L soul 38000 miles) does this engine also have those same issues? i do use exxon top tier fuel and use lucas fuel treatment does this cars engine have those same characteristics as the ones having trouble with the carbon build up or is the design differant thanks
 
#22 ·
I've been doing some reading on GDI engines in general and it appears they have a problem with carbon build up on the intake valves resulting in poor operation upon startup from the design my worry (I just got a 2013 1.6L soul 38000 miles) does this engine also have those same issues?
There has been a lot of speculation about the issue, but I don't recall seeing anyone who actually had problems due to this. So maybe it's not a problem with this engine. It's been out for 5 years(?) now, and one would expect the high-miles engines to be suffering, if it was indeed a problem.
 
#17 ·
The only fuel additive that's suggested by Kia or Kia dealers, is "Techron" from Chevron.

I'm a bit confused, why there would be any carbon buildup on the intake valves anyway. The only carbon buildup that affects the CDI engine is on the Fuel Injectors themselves.
Since I buy the cheapest fuel I can for whatever area I'm in at the time, I just add a bottle of Techron fuel system cleaner ever 3k miles, along with the rest of my 3k Maintenance. Now at 60K+ miles, I've never had the first hint of any carbon buildup in my engine at all. I've never had any misfires, poor starting or any other engine failures, in five years.

I don't baby my engine either. Some would say that I drive it like I stole it. Well, not that bad, but I do red-line it as often as is convenient.

Good Luck, and Happy Motoring!
FL Hamster :cool:
 
#18 · (Edited)
Since DI injects the fuel directly into the cylinder, regular fuel cleaners do not pass over the outside face of the intake valves, meaning they don't get the cleaning effect. Now the only thing passing by the intake valves is fresh air and the oil fumes from the PCV. From what I've read at many sources, the oil fumes can cause deposits to build up over time. This requires an engine disassembly in the worst-case scenarios in higher mileage vehicles.
Spot-on. Sure there is a lot of blow-by on those new economical engines (less tight cylinder rings, less friction), and the more you can do to help them, the longer they will last. I avoided buying a GDI car for now (or Turbo), and I intend to keep avoiding them.
However, I am using synthetic oil in all my cars anyway, there is no reason why I should "save" money on something that I do maximum twice a year (I do my own oil changes, so I save there).
I am adding Techron now and then, because is recommended by Hyundai/Kia and Mercedes. That's good enough to me.

To clean the intake valves you could use the Seafoam that gets injected right past the throttle valve, but I am not sure how that works with the GDI engines (more sensitive to the air/fuel ratio?)


I'm a bit confused, why there would be any carbon buildup on the intake valves anyway. The only carbon buildup that affects the CDI engine is on the Fuel Injectors themselves. :
The first post is pretty clear, you just need to read it :).
The GDI system injects fuel directly inside the cylinder, around the spark plug location. The fuel it doesn't "wash" the intake valve anymore, like is the case when the injection happens "outside" of cylinder, close to the intake valve.
The exhaust valves are hotter than the intake valves, because of the hot exhaust gases passing by. Any carbon build-up gets burned on the exhaust valves.
The intake valves not being "washed" by gasoline (detergents) have less chances to be cleaned up so build-up of carbon remains on the intake.
 
#20 ·
On a serious note (I hate when this happens) it's going to take more than a can of any aerosol product to clean dislodge coked on deposits on the back of your valves.
The best way to remove deposits is to prevent them from the start.
The catch can controversy continues to be a viable option in valve-train health.
With the 100k warranty though the issue may only be an issue for those who keep their souls till death do them part and not for those who lease or drive under the 12k a year average.
 
#23 ·
The carbon buildup problem in the GDI engine is NOT on the valves, but on the Fuel Injectors themselves. That's why Kia recommends using Chevron Techron, at regular intervals, to help burn away that carbon buildup.

The will never even be a problem if Soul drivers would just RED-LINE their engines every few days, to "Blow the Cobs Out".
I probably don't need the Techron at all, but I use it every 3k miles anyway, just to be safe. Why wouldn't I need it?
Because I don't baby my engine at all. She's never happier than when she's taching up over 5000 rpm. She's in her Power Band and running like a scalded cat!

Cheers Mates!
FL Hamster :cool:
 
#28 · (Edited)
I once read an article about how much money VW spent trying to develop their own DFI engine.
It was a bundle! And, it didn't happen over night.

Hopefully Kia benefited from all that R&D and didn't have to re-invent the wheel.

But even with all those millions invested, DFI still has it's little quirks. But now we know, two things that we can do, to combat the carbon buildup on the fuel injectors, even though Kia only told us about one of them.

#1 Is "Techron" fuel system cleaner. Use every 3000 miles.
Hair coloring Material property

Click image to enlarge

And what was #2?
Well, it's something we've talked about quite a bit on this forum. It's really simple and costs hardly anything at all. It just involves getting your engine up to high enough RPM's to blow the carbon off of the fuel injectors. That usually means 5000+ RPM.

Cheers Mates!
FL Hamster :cool:
 
#29 ·
I'd pay (a little anyways) to see a simple comparison test to evaluate 20 identical cars, 10 using techron (or any similar fuel cleanser) and 10 using only regular gasoline for 50,000 -100,000 miles. Break those down and show us the results. Any difference? I suspect very little difference, but I could be wrong and therefore would love to see it. Empirical evidence.

Greg
 
#31 ·
Duh! That's what R&D is all about. Kia already did it!!!!

And their conclusion is that a DFI engine run slow, WILL result in carbon buildup on the Fuel Injectors.

Otherwise, they would never even mention it in the Owners Manuals, tsb's etc. And that's exactly why we talk about using "Techron" fuel system cleaner to abate the problem.

Do we really need to keep going over this time after time?

:cool:
 
#32 · (Edited)
There is no reason why the buildup would be on the injectors. That's not where the oil comes in the cylinder.
Because of the the direct injection, Techron or other detergents from the gasoline cannot reach the back side of the intake valves, only fresh air goes trough there, carrying with it oil droplets from PCV system. That's obvious.



So no cleaning of deposits via gasoline detergents (or Techron) on a GDI, you need to "cook" those valves to clean them. Make smaller coolant passages around the intake valves and you are "good to go". By doing that you are also "cooking" the guides, the valve seats... Germans from WV probably don't like that alternative, so they might cool more those valves.
 
#33 ·
What's funny to me about this, "Top Tier Gas" is that it is the same gas from the same pipe from the distribution center with a bucket/bottle of additives added (Techron, etc.) to the gasoline as it leaves the depot.

You should get similar results by just adding in the cleaners regularly, such as when you get the oil changed just pick up a bottle from the store. As pointed out by FLHamster above.

I am, though, interested in the longevity of the GDI by Kia, in the carbon collection.
 
#34 ·
Injectors become clogged from fuel impurities and varnish not from carbon.
G.D.I. valves get mucked up because they are no longer being washed clean by fuel as it passes over them.
While it may or may not become a problem it should be a concern for those who know enough to be concerned about these things.
For most, I'm afraid, ignorance is bliss and they'll just keep driving till the warranty runs out.
Precautionary measures like synthetic oil and catch cans will help remedy though not eliminate completely the sticky wicket/sticky valves.
 
#37 ·
Sorry to resurrect an old Post.

Some of you may remember my "Rio" post a years back. I had the short block and valve train in my baby replaced under warranty with around 60k (KM) on it. Now, at 67k my beloved Soul is starting to show signs of carbon buildup. It bogs out when coasting around 40km/hr and I have to tramp it to get speed. Everything shakes and I get looks from people walking. I brought it in to the dealership and they said "we can't replicate the issue, are you using top tier gas?". "Yes" I replied, "I only put Shell 91 in her". "If gets worst, come back and see us, but the computer is showing everything is working like it should".

I checked the throttle body for carbon yesterday and it's clean as a whistle. Even the intake after the TB is clean (the best I could do with a cellphone flashlight).

I'm really hoping this isn't a carbon issue. Anyone else have something similar?

Thanks!
 
#39 ·
Not sure about it bogging at 40 kmh / 24 mph, but there are definitely moments where there's delay in throttle response. I haven't noticed at what speed(s) that occurs at, though.
I don't believe that would be associated with carbon build up, you would just have less power throughout would be my guess, and not just at that speed.

I find myself using the manumatic, and flooring it through all gears just to get going. It's hot in Texas, my A/C is blasting, and it's hilly. The 1.6 definitely doesn't cut it

Can you elaborate on the shaking?
 
#38 · (Edited)
I haven't had any symptoms you describe. Do you get it out on the highway and open it up very often?

As I understand it carbon buildup was a bigger problem on early GDI engines. (German engines were hit hard). Engine design played a big role in carbon buildup.

On the NU 2.0 & Gamma II 1.6 engines (Soul 2012-) from Kia with CVVT the problem is far less, unlike early Beta engines. Technology & design with tight specs have advanced to deal with this problem.

I run Shell 87 as recommended in my owners manual (the 87, not the Shell):)
 
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