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2019 Sorento
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41 Posts
Discussion Starter #1
Just curious if any folks with over 30,000 miles on the V6 GDI are experiencing any issues related to carbon build up? I know this is a known issue on gasoline direct injected engines and I'm just curious how prevalent it is with MY 2016+ Kia Sorentos with the GDI V6 engine?

Also, anyone clear up carbon build up issues with a basic like CRC's intake valve cleaner: How To Use CRC GDI Intake Valve Cleaner - NAPA Know How Blog ?
 

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2016 Sorento SXL
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1,133 Posts
If it's happening, it's not happening widely or quickly. While we see a lot of angst over it in this forum, we don't see reports of performance/compression issues that would result, and there are a LOT of 3.3L GDI engines represented here that whose 30K miles on the odo are WAY back in the rear view mirror.
 

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2018 Sorento LX V6 AWD Conv. Pkg. Tech Pkg.
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194 Posts
Forum member rebelshadow reported a year ago that his 2014 V6 Sorento with 287,000 miles runs like new, without any special maintenance. I think that tells us that those who put on a lot of miles have nothing to worry about. It would be good to hear the experience from folks like me that don't put on a lot of miles.

 

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2017 Sorento SXL
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128 Posts
it all depends what speeds you drive at. if you do mostly city driving you should definitely use the GDI valve cleaner as instructed.
 

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2019 Kia Sorento LX V6 AWD
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10 Posts
46,000 miles on my 2019 and still running strong. I got the car used, and I suspect most of those miles are highway miles. In the future I'll be doing mainly shorter trips, so I'd like to know if that valve cleaner would be a good idea going forward.
 

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Sorento LX V6 2018
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451 Posts
I'll give you my personal opinion, not backed up by any scientific data or even anecdotal data. One of the worse things you have always been able to do to cars is to do what I call short starting them. This is driving only a few blocks or maybe even a few miles, never allowing the engine to reach optimum operating temperatures. Now, I know for a fact that this will cause excessive carbon buildup in the combustion chamber, having looked at more than a few with this issue using a borescope. It can also wreck havoc on the exhaust system.

I think in a GDI engine, reaching proper operating temperatures, and likely operating at those temperatures for a while, is critical to minimizing buildup on the valves. Short starting them will create buildup very quickly and in significant quantities as to impair operating performance. Again, just my considered opinion after 50 years of tearing into motors as a hobby and as a moderately successful builder of race engines for the spec Miata racing class (unfortunately, much better builder than driver :( ). I don't think total mileage matters one wit, as long as the car is being warmed up properly.

I've taken to using the CRC cleaner but have to tell you it's a PIA to use. First, you have to maintain ~2K rpms during the injection process - with electronic throttle someone has to be in the car modulating the throttle, no more doing it by hand at the throttle body. Second, at least on the V6 engine, there is no available vacuum port that can be conveniently utilized so you have to loosen the air pipe at the throttle body, slide the injection tube under it and inject the fluid. Because the straw is being held tightly in place by the air tube, any movement of the can itself results in the straw being pulled out of the can and you've got to stop and reassemble the apparatus and stopping is not part of the instructions until the end. And then of course, I have no idea if it's actually doing anything. If it's not working, I've wasted $10 a can every 10K miles on the cleaner. If it is, I may have saved a lot of money down the road from not having to blast the valves with walnut shells to clean them.

I only worry about this because I tend to keep cars for 10-20 years and well over 200K miles (I get my wife's hand me downs). If I was upgrading every 100K miles, I probably wouldn't worry about this at all although that raises an interesting question - is the buildup covered under warranty or considered a maintenance item? If the car starts running poorly before the end of the 10/100 period, is Kia on the hook or will they call it a maintenance item and hand me the bill? Don't know if anyone has encountered this aspect of it yet.
 

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2018 Sorento LX V6 AWD Conv. Pkg. Tech Pkg.
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194 Posts
Is there anything easier than the CRC that is effective? I do a lot short distance driving. I only put on about 5k miles per year. If a problem didn't surface until 100k+ miles, that would take 20 years for me.
 

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2016 Sorento SXL
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1,133 Posts
Due to the GDI design, nothing you put into the tank will help -- it has to be in the intake, and the problem there isn't the CRC, it's the method you have to use for that or any other similar cleaner. Might as well stick with the CRC product since it seems to work well, and you're stuck with the method regardless. If there was an easier spot that would get the stuff into the intake, that would be nice, but ...
 

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2019 Kia Sorento LX V6 AWD
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Is there anything easier than the CRC that is effective? I do a lot short distance driving. I only put on about 5k miles per year. If a problem didn't surface until 100k+ miles, that would take 20 years for me.
My last vehicle was direct injection and I drove it 27 years, had 166,000 on it by that time (less than 7k/yr). The majority of those miles were city driving. When I sold it the engine was still going strong, but the plastic parts like interior lights and steering wheel were starting to crumble away. I never did any valve treatment or really anything beyond basic maintenance. There may be something about the Kia engines that make them more prone than average for carbon build-up, I don't know, but I haven't heard that.
 

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2018 Sorento LX 2.4 FWD; 2009 Borrego LX V6 RWD
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158 Posts
I just did the CRC spray can treatment at 35K miles, and I do notice slight improvement in smoothness of the engine at startup and idling. I also cleaned the throttle body valve while I had access to it. There was slight buildup of gunk around the valve edges. I don't know if it's cleaning of the intake valves or the throttle body valve that's making the engine run more smoothly.

Since I didn't have a helper, I resorted to setting a golf driver between the pedal and the seatback to maintain 2K RPM. As for using the spray can, I found it easier to not use the straw and just spray directly from the main nozzle.

I also changed the engine oil and the transmission fluid drain/fill for the second time in 5K miles, and the car is running better than when new.
 

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2019 Kia Sorento SX
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6 Posts
Is there anything easier than the CRC that is effective? I do a lot short distance driving. I only put on about 5k miles per year. If a problem didn't surface until 100k+ miles, that would take 20 years for me.
Same with me, I do a lot of short distance driving, and put on about 5k a year too. I am wondering if carbon build-up is something I need to worry about. Would it be covered under the warranty if under 10 years old? Also, what are the common symptoms of carbon buildup?
 

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2016 Sorento LX V6 AWD
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534 Posts
I definitely started noticing issues with hesitation and loss of power around 35k. There was a clear difference after doing 2 CRC treatments in a row. And ever since then, I can tell when it's time to treat it again, because the same symptoms come back within ~10k miles. It's pretty much like clockwork.

The problem with giving general advice on this subject is that:

1) Not everyone notices the symptoms. The symptoms also increase slowly over time, so if you never clean the valves, you might not notice anything for a long long time.. like 100k miles or more.

2) Everyone keeps their vehicle for a different amount of time. If you put 5k per year on the car and only intend to keep it for 3-7 years, you don't need to treat it. If you put 12-15k per year on the car and you want to keep it 12-15 years, you absolutely need to treat it regularly.

And you have to think rationally about this stuff too. You can try to change it if you want, but the way you drive is the way you drive imo. If I'm doing a lot of short distance trips, that's because my life demands it.. I'm not gonna disrupt/change the way I live just to prevent some carbon buildup (especially when I can treat it for $12 in about 10 minutes).

So it really depends on a lot of things. My advice: spend the $12 and do the treatment when you reach about 30-35k miles (assuming you want to keep the car for at least another 30-35k). If you don't notice a difference, don't treat it anymore.
 

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Sorento LX V6 2018
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Due to the GDI design, nothing you put into the tank will help -- it has to be in the intake, and the problem there isn't the CRC, it's the method you have to use for that or any other similar cleaner. Might as well stick with the CRC product since it seems to work well, and you're stuck with the method regardless. If there was an easier spot that would get the stuff into the intake, that would be nice, but ...
I've thought about tapping a nipple into the throttle body just to use as an injection port. It would obviously involve drilling into the metal, properly tapping the hole and then installing the nipple so it didn't interfere with the movement of the butterfly. It would likely have to be done off the car so no shavings went into the intake. Probably more involved than I want to get at this point since I can just see something going wrong under warranty and someone claiming that drilling into the TB was the cause! Gone are the days when there were plenty of vacuum lines running off the intake track - now everything runs off of distribution blocks with various valves and disconnecting any of those lines probably throws a code or doesn't inject the cleaner at the right point in the intake system.
 

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2017 Sorento LX 2.4L AWD 7 Passenger
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My 2017 2.4L AWD LX (former Hertz rental) started throwing a P0420 Catalyst Low Efficiency code at 60k miles. I purchased this vehicle last spring with 45k miles.

Since it was a former rental car, I assume it had bare minimum maintenance and was driven with no mechanical sympathy.

It was in pretty good cosmetic shape and had new tires, brakes and a Hyundai oil filter on it when I purchased it from a Hyundai dealer.

It was just out of warranty (61k) when it threw the P0420 the first time. I am a former auto tech and understand the concepts of how a modern vehicle works so I started to diagnose how Kia determines cat efficiency, code setting criteria and normal operating parameters. This is my first experience with a GDI vehicle. I have a professional scan tool and can interpret the data. Kia has excellent service literature also!

My vehicle was right on the line of setting the MIL according to the O2 sensor data. I priced parts and they are EXPEN$IVE! $1400 for a cat, $250 to $300 for the O2 sensors. The sensors still worked but the readings were borderline so it really did look like a damaged catalytic converter.

After reading up on GDI and some of the issues intake carbon can cause, I decided to try the CRC GDI intake and turbo cleaner . I treated it twice in about 1500 miles. I also have begun using Techron fuel system concentrate plus at every oil change (5000 miles, synthetic oil).

It has 68,000 miles on it now, the O2 data looks much better, nowhere near borderline now. Gas mileage has improved and the vehicle runs better. I can convinced intake carbon is an issue but is manageable with regular maintenance.
 

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2011 Forte SX 2.4L (thankfully MPI) A/T 144K miles
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…. I am a former auto tech …
Guess the shop you worked at never told you about the 8 year/80K Federal emissions warranty, which remains in effect regardless of ownership, and will cover the cost of parts+labor on the cat.
 

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2018 Kia Sedona lx
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6 Posts
I used Just answer to discuss this with a Kia ASE mechanic. I wanted to know if I need to use crc valve cleaner to prevent carbon build up. Here is our conversation:
Hi David, nice to meet you. Let's start with what type of fuel you use. What brand is your normal fuel when you fill it up or add some?
Me:I am going to be using fuel from Exxon.
ASE guy:
Ok great. In that case, you will not need to use any fuel/ intake valve cleaner. The reason is because Exxon is a "Top Tier" fuel which has great cleaners in it already. This will prevent intake valve deposits. Some engines have problems with carbon buildup even with top tier fuel, but this engine is not one of them.
You will not need to use any of this chemical.
Me:Okay. Thanks. I thought the fuel does not come in contact with the intake valve which cause the carbon to build up since fuel is not washing over it.
ASE mechanic:You're very welcome. The fuel will be sprayed into the cylinder as the intake valves open so it will get a little bit of fuel on it. It does not "wash" the valve per say because it is direct injection but it will get some on it.
 

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2019 Sorento LX AWD 3.3L
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38 Posts
I used Just answer to discuss this with a Kia ASE mechanic. I wanted to know if I need to use crc valve cleaner to prevent carbon build up. Here is our conversation:
Hi David, nice to meet you. Let's start with what type of fuel you use. What brand is your normal fuel when you fill it up or add some?
Me:I am going to be using fuel from Exxon.
ASE guy:
Ok great. In that case, you will not need to use any fuel/ intake valve cleaner. The reason is because Exxon is a "Top Tier" fuel which has great cleaners in it already. This will prevent intake valve deposits. Some engines have problems with carbon buildup even with top tier fuel, but this engine is not one of them.
You will not need to use any of this chemical.
Me:Okay. Thanks. I thought the fuel does not come in contact with the intake valve which cause the carbon to build up since fuel is not washing over it.
ASE mechanic:You're very welcome. The fuel will be sprayed into the cylinder as the intake valves open so it will get a little bit of fuel on it. It does not "wash" the valve per say because it is direct injection but it will get some on it.
FYI, the amount of time that valve will be in any fuel exposure is too small to matter. Go with the cleaning regime.
 

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2017 Sorento LX 2.4L AWD 7 Passenger
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Guess the shop you worked at never told you about the 8 year/80K Federal emissions warranty, which remains in effect regardless of ownership, and will cover the cost of parts+labor on the cat.
Nice.
Yes, I do know the 8/80 federal warranty. I also did not want to pay the diagnostic fee to diagnose that everything is working fine or perhaps have the shop parts cannon loaded with $500 for a couple of O2 sensors.
But hey! Thanks for being helpful!
 

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Sorento LX V6 2018
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451 Posts
I used Just answer to discuss this with a Kia ASE mechanic. I wanted to know if I need to use crc valve cleaner to prevent carbon build up. Here is our conversation:
Hi David, nice to meet you. Let's start with what type of fuel you use. What brand is your normal fuel when you fill it up or add some?
Me:I am going to be using fuel from Exxon.
ASE guy:
Ok great. In that case, you will not need to use any fuel/ intake valve cleaner. The reason is because Exxon is a "Top Tier" fuel which has great cleaners in it already. This will prevent intake valve deposits. Some engines have problems with carbon buildup even with top tier fuel, but this engine is not one of them.
You will not need to use any of this chemical.
Me:Okay. Thanks. I thought the fuel does not come in contact with the intake valve which cause the carbon to build up since fuel is not washing over it.
ASE mechanic:You're very welcome. The fuel will be sprayed into the cylinder as the intake valves open so it will get a little bit of fuel on it. It does not "wash" the valve per say because it is direct injection but it will get some on it.
Let me apply my BS interpreter app to this and publish the results:

Mechanic: We don't want you to try anything that might maintain the car properly and take away work from us. So, we'll give you some BS about fuel still washing the intake valve.
You: Should I just give you my wallet now or would you prefer it over time?

The whole idea of GDI is a good one - precisely measured fuel delivered into the individual cylinders directly where it then mixes with the air from the intake side. That means it is not coming into contact with the backside of the intake valve. Therefore, no fuel treatment will help - it will keep the face of the valve clean for what that's worth.

Still, carbon buildup is a tough one to diagnose while it's in process, only after it has caused driveability issues. So maybe Kia motors don't develop it for some other reason and it will never be an issue. Personally, over maintaining has always been my route versus not doing enough.
 
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