Anyone tried cleaning their intake valves with chemicals through the intake? (Stuff like BG, CRC, Sea Foam etc)
I'm worried about the longevity of the intake valves but I've also read that doing this sort of service can cause carbon chunks to scour the cylinder walls or even end up in the catalytic converter.
Ideally, I would have used something like this from the get-go as preventative maintenance but I'm at 45k miles; not sure if it would be a bad idea being this far along.
Thoughts?

 

If you have build up to the point where you could actually have "chunks" break off... the first thing you need to do, get better gas.

A decent gas station has gas that has "detergents" mixed in. That alone should be preventive measure against that much build up.

At 45k miles with anything other than total crap gas isn't going to get enough of anything inside to worry about.

As for stuff like Seafoam or whatever, I don't know... never tried the stuff. I have 136k miles and so far, haven't encounter a reason to use those products.

 

Wow you already have that many miles on your GK? That's a relief to know. I take it that most people who've had problems with hardened carbon chunks coming off, probably started those services when they already had trouble. I think you're right about the gas. I've only ever used Top-Tier. Anywho, what piqued my interest in cleaning the intake valves was when my car was new, I managed to get 45mpg over a thousand mile stretch. Lately, I haven't been able to pass 45mpg on the meter while cruising. In the past, cruising would net me 47mpg+ on the meter. Earlier this week, I poured a bottle of Techron into the tank, kept the RPM high for at least a half hour and I was seeing the old numbers again. The problem with fuel additives though is that they supposedly do nothing for the intake valves.

 

Goobers above has a GE, so no carbon fouling concerns like you have.

I've done Seafoam on other cars with decent results. My opinion is that you either want to start doing induction cleaning early on (you're still in time) or not at all. That avoids the likelihood of large amounts accumulating which avoids the possibility of chunks. In other words, I agree with your concerns, but think you are early enough.

Amsoil makes a product called Power Foam that I've read good reviews on. I like that it's a foam so that it can, in theory, sit and dissolve better than a pure liquid like Seafoam.

If you give this a go, let us know the results.

 

I was going to try it right before getting an oil change but honestly, I've never worked on a car before. I have no problem removing the top of the air box but the whole assembly is clamped and bolted down in all these spots that are too intimidating for me to deal with. I asked my mechanic if he could help me with it and he assured me that induction cleaning the intake valves are completely unnecessary on modern GDI engines. He says all you need to do is run two tanks of premium fuel through it.

 

Since the back sides of the intake valves never see the gas (it's injected directly into the cylinders), how can fuel "quality" make any difference?

 

This is a bit controversial, NOTE that I'm just repeating what I read on other Forums.



Because of potential carbon buildup, one design feature that many manufacturers use is to spray the DI 'horizontally' across the top of the cylinder. Their hope (?) is that when the valves open, the valves will be in the path of the spray.

Valves are supposed to rotate a bit as they open so spraying one side is OK.

So, the use of High Detergent gasoline (Top-Tier) is recommended to reduce buildup.

By the same process, the use of Premium gas is supposed to help also, as it 'encourages' the ECU to spray the gasoline earlier (less danger of pre-ignition with 93 octane).



Obviously these steps are not a cure-all. Some manufacturers are starting to include supplemental port injectors to to aid in the dispersal/prevention of carbon.


I think it will be a few years/development cycles before we get a GDI system that is as reliable as port injection. (But only if GDI engines are not banned because of the particulates they produce.) <SIGH>

 

Can't you just take off the airbox, spray the foam in with the throttle open (and the engine off!) then run it?

 

 

I'm trying to address the same problem. Given that Gas Direct Injection (GDI) engines like the ones we have the gas never touches the valves, or the back of the valves like Port Fuel Injectors where the air and fuel are mixed before going through the intake valves. Gasoline is a fantastic cleaner so PFI engines typically have pretty clean intake valves since they're constantly being cleaned... so to speak. But with GDI engines only air goes through the valves with some oil and blow by. All that can build up on the back of the valves. Gas doesn't get mixed with the air before going in to the cylinders. Instead, gas is being directly injected into the cylinder. Hence Gas Direct Injection. So having high quality fuel may help with engine performance, it won't help keep the valves clean. This is why I'm trying to address this build-up issue by cleaning it and I'm considering using CRC GDI cleaner. I know many have done this method with great results on other GDI cars from Mazda, Hyundai, VW, etc. So I'm wondering if anyone here has used CRC cleaner on their Fit. If so where did you inject the cleaner nozzle?

 

I thought about doing this too, but haven't gotten around to it.

 

If anyone does this, can they please submit a video on how to access the throttle body? There's a lot of stuff connected to the whole intake assembly and I'm a complete newb when it comes to working on cars.

 

Yes, please. I would love to know.

 

Changing the oil as recommended, having a properly functioning PCV system, and properly functioning EGR system, having the valves properly adjusted, having well-functioning spark plugs and correct ignition timing, as well as using gas with adequate detergents (Top Tier) have all been said to help minimize carbon deposit buildup, on the inside surface of the valves.

As we know, crankcase pressure builds up from combustion blowby (combustion gasses blowing past the combustion rings into the crankcase) so it needs to be vented, or else it prevents proper engine operation by pushing back against the pistons in the wrong direction. One theory is that it also contributes to an oily film forming in the combustion chamber and on the valves and then the film helps carbon stick to the valves. If the cv hose and the pcv valve are working properly, crankcase pressure doesn't build up, and oil from the crankcase doesn't get into the combustion chamber as much. So according to this theory a properly functioning pcv should help prevent carbon buildup on the valves. Also well-functioning oil-control rings sounds like it would help, as well as properly functioning ignition. I would think that a proper air to fuel mixture would help too. In engines that have port injection, or carburetors, perhaps they are more forgiving, should they not be running with ideal ignition adjustment, fuel air mixture, and crankcase ventilation. Perhaps direct injection engines are simply less forgiving and only suffer from buildup if one or more of these systems aren't functioning well. I wonder if carbon buildup has been exaggerated in the media, and I wonder if the cases where it has been shown to have occurred are in engines where the mixture, ignition, and cv system were not functioning at proper levels?

Also, if you watch the earth dreams video (if you watch it in youtube you can see it full-screen) it does appear that the injectors are angled and timed so as to get some fuel onto the inside surface of the intake valves. The L15B1 engine didn't go into production until 2014 so Honda engineers had time to learn about how some older direct injection engines were prone to rapid carbon buildup, and how others suffered more slowly from buildup, and to design the LxxB1 engines with minimizing buildup in mind. I think how good a job they did with this engine remains to be seen. Toyota, the king of reliability, is resorting to making their engines more complicated, by having port injection in addition to direct injection. Honda has a reputation for more elegant engine design solutions, and I wonder how carefully they designed the combustion chamber and the direction of the fuel injector spray pattern.

 

i love this movie... ... gets me right in the feels.

 

Cleaning the injectors through better gasoline and additives will NOT clean the valves.
These engines have direct injection, gas goes straight into the combustion chamber from the injector, NOT though the intake tract or over the valves.

 

Yes this has been stated. I have also read that the vapors after combustion can help keep carbon build up at bay even when not sprayed directly on the valves. Not sure how true this is. Using a gasoline with additives helps with other parts like the tops of the pistons and piston rings.

Is this even an actual problem the L15? Other manufactures have has issues with it but maybe Honda has a way to combat it. The newer Pilot has a DI engine and from what info I can find it has not had issues.

 

In some of their Earth Dreams engines, Honda positions the injectors so that they squirt across the combustion chamber, onto the open valves. As the valves rotate, the spray is intended to keep the valves from building up too much carbon.

 

My wife's 2017 6 speed just had the carbon buildup problem (29969 miles)
I did a lot of research and realized that # 3 cylinder is the one most affected, it is also the cylinder that gets deactivated during low throttle or idle to increase fuel mileage is this a coincidence?
Also it seems like manual transmission cars are more susceptible to carbon build up as they are driven harder in lower gears causing more heat in the engine. CRV's are plagued by gas in the oil, also from # 3 cylinder thinner oil causes more blowby gasses. I wonder if a catch can is in order for the PCV.

 

You are the first I have heard from regarding any cylinder deactivation in the 4 cylinder engines. This is Honda's statement regarding their Earth Dreams engines and only the V6 discusses cylinder deactivation. Honda News Press Release