so now i need to worry abt carbon build up on my 18 fit ? =S

i bought NA engine car hoping that carbon build up problem would be less then those turbo/supercharged engines...

i guess any engine with direct injection cannot run away from carbon build up..

You need to worry about it on your intake valves but not on the throttle body. And you can mitigate the buildup on the valves with a pcv catch can.

ahh i see....just blasting engine with high RPM every now and then wouldn't work? =S

This would be the perfect scenario to have a hidden camera in the engine bay to see this hand cleaning of the fuel delivery system :rolleyes:

Please continue to have 25 minute conferences with them on the subject. The more time you spend with them, the less time they have to scam someone else.

Every car's engine needs carbon cleaning, it's just whether a consumer chooses to do it or not. I just cleaned the intake manifold and throttle body on my 07 Accord V6 at 305000 miles. The only hand scrubbing you'll ever get, is when you do it yourself. I doubt a dealer would ever do that. I started doing throttle body cleaning almost 20 years ago, on my 1998 Accord V6. If you didn't do that, the throttle plate would stick inside the throttle body, and with mechanical cable actuation, the gassing operation at the pedal became sticky and not smooth. The "spray solution" is a $3 carb cleaner you can get from Walmart, don't be fooled that Honda dealers have something special. As for the 4 injectors in the Fit, it might be cheaper to just change them out at 100k miles instead of cleaning them. Fuel injector cleaning usually involves a professional service instead of spraying it down, because you need to pass cleaning solution through it while pulsing the injectors. It will only clean if you turn them on and off repeatedly with cleaning solution through them.

will using sea foam help reduce carbon build up also? =S

I wouldn’t call it a problem with the L series. I wouldn’t worry too much about it and until someone looks at the valves with 50k on them, cleans them, installs a catch can and checks again at 50k more miles I’m not sold on catch cans.

There is a thrad about it on here somewhere.

I stopped running sea foam years ago. Run sea foam through vacuum ports on the manifold only if you don't know how to take the intake manifold off. But the cleaning isn't complete. I run marvel mystery oil through the fuel system and engine crank case, and take the intake manifold off and use oven cleaner in the runners, then carb cleaner on the throttle body.

Carbon built-up isn't a "problem" on any engine, it's normal that it happens, just a matter of taking care of it every so many years.

Just 87 regular gas. I tried premium for a few months but saw no advantages and have gone back to regular. Premium does supposedly contain more detergents beyond what's required (even for top tier) but there's no way to confirm that and whether it makes any difference and it might just be oil company BS to try and sell a more profitable grade of gas.

I do think the carbon issue is being blown out of all proportion. Setting aside the fear mongering, there are a lot of Fit cars from this generation which have racked up a lot of mileage now. Where are all the posts from their owners complaining about carbon problems?

Dear God OP, go to another dealer. These folks stink.

My thoughts too. From my looking into Honda carbon build up they do not have a problem. Yes carbon will build up but not like it does on other engines. People like to put all DI engines into this catagory as a blanket statement. Honda seems to have figured out how to keep it minimum (even on the Type R).

My GTI has carbon issues but it is nothing that a little DIY can't take care of every 60-80k miles or pay someone $300-$400. It is just part of normal maintenance for that engine and in no ways would I rather have PI to keep it from building up. I plan on adding water/meth to keep it clean after I do a full intake valve cleaning.

And yes go to another dealer or shop OP.

Edit:

Edit again:
https://www.civicx.com/threads/maybe...problem.24645/

https://www.civicx.com/attachments/valve-jpg.99597/

Lots of terms and pictures going on, I hope to add to the conversation - without contributing to the confusion.

All engines will burn a small amount of oil, which is due to a variety of reasons - blowby, pressurized chambers, recirculation systems.

Valves - I went all out and got an "induction cleaning", just to see what would happen... the gunk that had been holding the valves from leaking was cleaned off and as a result my H22 has bad valve seals, it burns a bit of oil that is conveniently captured by my rear bumper. I have replaced the PCV valve and EGR, but ultimately I will need to pop out the cams and redo the valve stem seals - which I will bundle into a port and polish, to reduce turbulence and bore out the breathing inlets. The RPM is really the only determinant here, the higher the rev's... the more gases will leak and the more oil you will lose (check your tailpipe). VTec likes to drink oil, but it isn't inherently an issue. In my opinion, if your valve stem seals are less than 10 years old - I intend to get an induction cleaning every 3-ish years... to remove build up. Carbon deposits will tear up your seals, so a clean engine will do better. Stem seals should last 15 years or 150k miles, so don't sweat them.

Piston burn - this is more of a warranty item, but has a super easy check - pressure test. Get a pressure test, do it dry... then add some oil, if the numbers move up significantly... you need new rings. Might as well also get the entire engine re-manufactured/ honed/ etc.

Recirculation systems - In order to comply with a variety of EPA regulations, our cars now breathe their exhaust systems. This creates a number of issues, the positive crankcase valve (PCV) breathes the oil laden air into and PAST the throttle body. As a result, oil gets caught on the butterfly (which is coated, so be careful if you clean it). Oil catches dirt and the gunk collects; my 2006 Mazda 3 was notorious for this, every 3 years I would need to clean the butterfly... but never burned oil. It was a 10 minute job and cost $5.

Direct injection will lead to deposits on the valves. Engines will burn oil. The only thing you can do is to replace parts when they need to be... oil, seals, and (yes) engines.

Gas octane has NO impact on any of this. Octane is a measure of when it combusts, please stop conflating detergents with octane, octane = detonation. If you have an NA engine, 87 is fine... UNLESS dealer specified tunes have been applied - check your gas cap.

I have 125k on my 18 Fit and will be doing the walnut blasting soon. I have had check engine codes P0420 and P219A come on and off for 30,000 miles now(air/fuel ratio imbalance). I paid Honda for the fuel injector cleaning treatment but that didn’t help. They then diagnosed the issue as failed injectors so I bought a used set from a junk yard but luckily discovered this site and realized it’s probably dirty intake valves causing the issue.

Here’s a good how to video in walnut blasting, I just wish I knew if the N54 bmw vacuum adapter would work with the Fit.
As far as what fuel to use - It’s not “top tier” to look out for, it’s ethanol-free that we should be using. Check out this Consumer Reports article from 2015:

”Some carmakers, including BMW and Kia, have issued technical service bulletins (TSBs) to their dealers recommending that drivers use only name-brand detergent gasoline—without ethanol additives”

https://www.consumerreports.org/cro/...ines/index.htm

Did you send a scope down to look at the valves?

I’d love to see some Honda valves with serious carbon build up on them.

My 2016 was trouble free (except for the starter button issue) until just out of warranty.

• All along, I bought tier 1 gasoline.
• Early on I installed a catch can.
• Did oil changes promptly using synthetic oil.
• Being a slow small car, I was always gentle on the throttle.
• Since day 1, I used Techron additive regularly.

Just out of warranty, it started hesitating during acceleration. The dealer wanted approximately $2000 for injectors & fuel rail. I told them to appeal to Honda for a good will repair.
They lowered the price to $700. This fix had the "New and Improved" parts. All was OK for a year, but now it's starting again!
Reading on this site and others about the issue, I saw the comments about running the engine hard periodically to clean carbon buildup.
Starting 3 weeks ago, during my drive home from work I floor it up close to redline on the freeway entrance ramp. Other times where I can, I accelerate hard from stops.
I have to say the car is running MUCH better. Almost normal in fact.
I think driving too easy does add to the carbon buildup (without looking inside) and driving hard keeps it clean.
My recommendation - Drive it like you stole it.

I'm not an automotive engineer, but I don't think you're going to hurt anything. For decades, I've had Japanese cars and motorcycles, and driven them hard, and I haven't blown one up yet. (And I really tried to blow up my '08 Fit :D .)

I run our '15 pretty hard, but was bought used with 40,000 miles on it, 66,000 now, so far all is well. Of course, after reading around here, I wonder if the original owner had whatever problems that popped up fixed, and traded it in? It's been a great car...so far ;)

I used this this stuff "BG" at 60K and can't really tell if there is a difference in performance?
I empty the tank and put the BG in, fill it up, and drive it down to empty again.
A shop owner in Beverly Hills told me that is what he uses in his client's Ferrari's and Maserati's on every service so I figured then good enough for Honda?
What do you think?
Every 10K or 20K miles?
Waste of money and time?

https://cimg3.ibsrv.net/gimg/www.fit...aefc40c32f.jpg

Oh well then if it's being sold to those people then it's guaranteed to be overpriced snake oil.

I don't like additives of any kind. They either do nothing, or they do harm (gum things up). I do use Chevron gasoline, which has Techron already in it. Most premium gasolines have detergents already in them.

Of course, lots of people use additives, and lots of people swear by them. If you can find a site like Bob Is the Oil Guy, and you are willing to put in the time, you can figure some of this out for yourself.