Direct injection engine?
 

the 2nd gen RDX is a J35 engine that employs Port injection.
I believe Honda's direct injection engines are called "Earth Dreams"

Regarding the issues associated with direct injection, premium fuel, even premium fuel with a ton of extra additives, won't do diddly.

Honda's Earth Dream engines were developed way later in the game than earlier DI engines and hopefully doesnt have those issues.
other auto manufactures recommend a walnut blasting of the injection ports to clean the carbon deposits left behind.

Yep, no direct injection. The RDX engine is basically the 2013-17 Accord V6 motor tuned for premium. And there is nothing wrong with that at all.

AGREED...except for VCM, which can be easily disabled.

That's a good vid. Makes me hesitant to want to buy a car with DI though. I know they can enhance the ECU's ability to control fuel and combustion better, but the side effects of nasty valves are a bit scary. Those valves were :ugh:

My last car was a VW with a TSI (turbocharged DI engine). Ran wonderfully, good mileage (when not in the boost range) and power, but the frequent stories of power falling off and rough idle generally starting at around the 50k miles mark and beyond made me think that while an interesting advancement, most car owners with DI probably are unaware of the problems that there cars will have (VW's tended to be some of the worst apparently). Attached in the link is only one example of a VW owner who found his valves to be extensively fouled. Most of the times the valves either are hand scrubbed or walnut hull blasted to remove the buildup which isn't cheap.

How ugly were your intake valves - VW GTI MKVI Forum / VW Golf R Forum / VW Golf MKVI Forum / VW GTI Forum - Golfmk6.com

DI seems to have some significant improvements over conventional port injection. I think I'd be willing to pick up a vehicle with a DI engine but I'd probably be doing some sort of treatment at least once a month as well as using a good quality oil catch can (or even just vent the PCV) to reduce the amount of oil vapor being passed by the intake valves. The treatment would have to be via the air intake or vacuum though, since treating fuel is pointless in a DI engine. There are a few out there. Seafoam of course but a couple others as well. I think I saw a can of cleaner specifically designed for DI engine valve cleaning last time I was at Autozone.

It would just be one of those maintenance items that comes with the territory of owing a DI engine. Better than paying for a thorough cleaning after several thousand miles, all the while suffering probable performance/mileage loss as well as some valve noise.

Edit: On that note, I had an oil catch can on my 4G for a while but I ended up getting rid of it because the valves were just as clean beforehand as with the oil catch can. Port fuel injection is a wonderful thing on intake valves. :tongue:

I suspect we'll see the trend of port and DI injectors for each cylinder will continue.

:werd: Ford and Hyundai have started doing that. Hopefully all the extra mumbo-jumbo doesn't result in more things going wrong. Fix one problem, create two more. Fuel injection systems are usually pretty stalwart though. But I heard those high pressure injectors and pump are uber-expensive.

unless it is a hybrid DI engine, you are going to have issues with soot buildup around the intake valves as no fuel washes them down. Your best bets are

1. oil catch can
2. spray seafoam down the intake every oil change
3. use top quality gas.
4. use oil specified for engine.

Good luck with all that....

How do you figure the quality of the fuel and/or oil will alter intake valve deposits?

according to those in the know better fuel creates less deposits because the additive package is better....

Those in the know say no such a thing.

Agreed on the first two. But I think you might be contradicting yourself on point #3. "No fuel washes them down" as you say. So I'm not sure how top quality gas would change things. For oil - I'd use synthetic and possibly go one viscosity grade higher to reduce oil evaporation which would otherwise be passed from the PCV into the intake manifold. I think most DI's recommend synthetic anyways.

lol oh really

https://www.youtube.com/results?search_query=direct+injection

pretty much all of the people who work on them say use top tier gas, oil specified, etc....

so let talking on your part and more reading is in order..

So, where in all of that crap you linked does it say better fuel keeps intake valves cleaner?

Spoiler alert; it doesn't.

Agreed that most DI's recommend top tier fuel but I believe that has to do with many DI's using higher compression or forced induction. And I'm sure top-tier fuel has the same cleaning effect on the piston head and exhaust valves. But again, it wouldn't have any exposure to the intake valves.

I have a coworker who drives a Kia Optima turbo and uses that CRC intake valve cleaner every once in a while. He's got about 50K on it and says he hasn't had any problems yet. It's supposed to have a crap-ton of PEA in it. If I buy a car with a DI engine that the route I'll probably go.

Top quality fuel , will have no effect on keeping valve deposit build up a bay on a DI engine. There is no washing of the valves as in the port injection engines, and that is what's required to keep them clean. The blow by gasses are the culprit. in this build up problem with DI. The use of a high quality catch can will greatly help and maybe the use of an additional filter behind it, but in the long run the blow by gasses are still going to cause accumulations or deposits on the intake valves. Seafoam isn't going to touch this problem, it may wet the valves down for a bit, but to break the deposits coming from DI, the walnut method will be the only way to get to the problem. From what I just learned about DI, I don't want one of them. My 2 cents issued.

I think if I opt for a DI engine I'd try to go the route of the "dual injection" engines they're designing, where there's both a port and direction injection system. They're starting to come out with those.

^ This.

I'm new to this forum. I came from the forum covering hyundai vehicles. I had a Sante Fe Sport...2014. Hyundai came out with there then new Theta 2 engine in 2011 which were all DI engines. Some of these vehicles now have over the 100k range and while the back side of the intake valves looked really bad (lots of carbon) in these forums nobody reported any engine problems associated with excessive carbon deposits, but in the long term I'm sure there will be...compared to traditional port injected engines. I put a catch can on mine(2.0t/264 HP) and at about 75k miles I removes the manifold to inspect the valves. They actually looked ok...but definitely had some carbon build up. Other pictures I've seen of the same engine without a catch can had much more carbon. I believe vehicles with DI engines should have a catch can as an OEM item. I suppose the dual injected type vehicle is a good remedy( Ford and Toyota). Bottom line if you keep your vehicle long term avoid stright DI vehicles.

:2cents: My wife's Sienna has Toyota's 2GR-FKS engine that has the DI and Port Injectors. It can also switch between Otto and Atkinson's cycle. It does not have cylinder deactivation. It's a pretty nice engine.

I just checked spec info on honda s version of the 3.5 V6 engine(2017 and 2018). I was surprised to learn the all the 3.5s used on Hondas are GDI....Ridgeline..Pilot..Odyssey. I doubled checked to make sure that the RDX was in fact port injected and they are..J35 series of engines. After just coming from a vehicle with turbo GDI I'm glad. I wouldn't have bought the RDX if it wasn't port injected.