The amount of vapors that are given off by the fuel when burned can affect the valve deposits on a DI motor. That's where fuel quality matters.

 

Your explanation makes sense. There must be some kind of exhaust gas recirculation and that's how the deposits from burned fuel get on the back side of the intake valve. I guess the increased levels of detergent mixture / ethanol results in a cleaner burn and, therefore, reduced carbon deposits.

With advances in materials science, I would think that it would be possible to make the intake valve out of some type of ceramic that would be difficult for the carbon to stick to. If there are issues, however, they are likely not evident during the warranty period, so manufacturers have no incentive to develop better valves unless it becomes such a huge issue that it affects sales. Absent of that, they have a disincentive because it would bring in more business to the service department.

That's a cynical view, I suppose.

The long term reliability and maintenance costs of DI engines are one of the things that concerns me. Hopefully my concerns are overblown and not a real issue.

 

I think it's wrong to state that manufacturers have no incentive to develop better valves because I believe they have already done so. There are far far fewer problems with deposits on DI than was the case when DI engines were first developed and released. Fewer problems now, but not no problems. Complaints about deposit problems on Fits are fairly rare, although it's uncertain if that will still be the case as the mileage on these cars gets a lot higher. Only time will tell.

 

That's good to hear. I haven't been following the technical changes over the years. I'm just learning about some of this since my girlfriend just bought a Fit and I'm trying to learn as much as I can about the car. I did see that owners of some DI cars - apparently not Hondas - had to have their engines pulled apart and have the valves blasted with walnut shells or something to get the carbon off. I think this was happening with only maybe 75k miles on the cars. Not in warranty and not cheap, I'm sure.

She and I both keep our cars for a while - her old Camry had over 190k on it and my 2008 Civic Coupe has about 153k. I'm thinking of replacing it within the next year or two. Right now I'm leaning towards a Civic LX with the 2.0 NA engine, in part because it uses multi-port injection rather than DI.

 

Carbon deposits on DI motors is definitely a problem and I think it's part of the reason Honda chose to be late to implementing its usage. They let others experiment.

Those that introduced DI early are now on to their second or third versions.

VW's answer to the problem was to develop a sophisticated EGR system that includes a separator that removes the vapor from the air and then returns the oil back into the motor and cleaner air back into the intake. Basically, they are trying to get the valves to see cleaner air. Not that unlike using a catch can system, but it's built in and more controlled.

Ford's answer is to bring back port fuel injection as an auxiliary system. This is my favorite method for cleaning the valves, but it does increase the cost of production and double the chances of fuel injection issues since they use two whole systems.

I'm with you FlaCharlie in shopping for a vehicle that just doesn't have DI at all. It offers minimal power or fuel mileage improvements. OEM's are forced to adopt anything that helps fuel mileage in the least due to government mandates, but I think a lot of the buying public would select the car that's $1,000 cheaper and less costly to repair (DI fuel pumps fail and are NOT cheap) and give up the 2-5% fuel economy or whatever it is. Those that are willing to spend the money and increase the potential repair bills are likely to be hybrid shoppers instead.

The DI turbocharged motors have an additional problem of Low Speed Pre Ignition (LSPI). Only time will tell how Honda's new 1.5 turbo will do long term in regards to durability. They built the exact thing that has the highest chance of problems (high boost at low rpms paired with small displacement), but Honda engineers are (or used to be) the best.

 

 

I believe it's in all levels of their gasoline. Just in minute quantities compared to what is in the treatment you buy in stores.

 

 

I believe Chevron Stations and Texaco advertise Techron as their fuel additive.
But I wouldn't say using that fuel replaces ever running a fuel treatment through your vehicle.

I lean..not exclusively but majority to using Chevron-with Techron, and then still occasionally running a treatment of Techron through my fuel system.

 

Are you my old "friend" SR45? Still loving my Fit, neighbor. Never did get to Bonnie's.

 

My Fit (2015, manual, 79k miles) recently had an oil change done by the Honda dealership I bought it from. They only charge $60, and given the hassle of doing it myself (I don't have a trolley jack that is long enough to reach the jacking point behind the engine), and the fact that they're within walking distance of my home, I'm willing to do that.

They hard sold me on a fuel injection treatment for $100, which they claimed should be done to all Fits at 80k miles (though I suspect that mine is likely the first third generation they've seen that has got to 80k miles: they've only existed since 2015, and I do around 36-37k miles a year on a long haul commute, which is very unusual). They claimed that it would restore fuel efficiency that he said I had likely noticed dropping off over the time I've had the car.

He was actually right about that: when it was new, it would get around 40-43 on freeway cruising, but by the time it went in for that service, it had dropped to 35-37. The treatment sorta worked: the MPG figures on the display are now claiming that I'm getting 43-45 for my regular, 63-mile commute to the office ... but ... doing the math based on the amount of actual gas burned during the miles between two fill-ups to the brim, the actual figure I got was 40.8; it said 44.1 on a trip counter monitoring that same fuel burn between fill-ups (I reset it just before the first).

So I don't think this was a total ripoff, and the acceleration certainly feels more responsive. But I can't help wondering if they charged me $100 to stick a bottle of something in my tank, that would have cost $20 at O'Reillys. I'd be very interested to know exactly what they did.

 

For purposes of the thread and in response to the OP however, one of the first things I asked was whether this was the dealership recommending a "Fuel Injector Cleaning Service" or just recommending using a fuel injector cleaner.

It seems this was just the recommendation to use a cleaner...not having some type of high priced "service" done.

I don't really know, but my opinion would be, I would never pay for a behind the curtain, dealership fuel injector "service" especially if I wasn't noticing any real symptoms.
They may or may not have value, but I'd be very skeptical.

 

 

Nice to reconnect!

 

 

Yikes! I know everything is more expensive in California, but still . . . Is $60 really considered a good deal on an oil change?? I typically pay $20 for my older Civic. Even at the dealership when they have a coupon. I know the newer Hondas use 0w20 oil, which is more expensive but I think they only charge $30 for that. And I would bet that all they did was to add a bottle of the same fuel injector cleaner that you can buy a WalMart, which sells the Techron for $7 or $8.

I haven't looked, but is there anything in the Owner's Manual that suggests that the fuel injectors need to be cleaned at 80k miles?? It seems to me that, since you were at 79k, it was just too easy to sell you something that was almost pure profit. Gotta love those dealership service departments.

 

 

I don't think I've ever seen or even heard of any manufacturer recommending a fuel system additive of any kind in the owners manual. I've seen statements in manuals warning against it. As far as what dealers recommend, well, these are the guys that tried to hose you for "documentation charges" and other completely unnecessary add-on charges when you bought the car. Why would you think that the mentality in their service department is any different?

 

 

I don't know. In my mind, it has enough detergents and burns clean enough to, hopefully, keep any deposits from forming in the first place. Not sure if it has enough to clean deposits that have already occurred since, in a DI motor, the fuel is not sprayed on the backside of the valve.

For that matter, I doubt even the concentrated boost from a bottle will help in a DI motor. The boost could help clean the injectors themselves though and possibly clean the tops of the pistons.

It's worth doing almost anything to keep the intake valves clean in a DI motor since there's no good way to clean them after deposits begin. On many platforms it's popular to run an oil separator to help keep vapors from being reintroduced into the system.

It's a very unpopular opinion with some people, but my solution since the '80's has been to only run good gasoline from the beginning. I stick with major brands like Shell, BP, Amoco, Exxon, Texaco, and Chevron. Only anecdotal evidence, but I have never had a fuel related issue in countless high mileage vehicles. Right now I'm using Shell almost exclusively in our two DI turbo cars. Not as much for it's detergent abilities, but for it's resistance to detonation/knock.