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Thanks for the good pictures and information! Always wondered how bad carbon deposit was going to be on the valves. Guess i will use the GDI spray before each oil change to help reduce buildup.
Uhhhh.... why?

This thread has proved that the J35 does NOT have major carbon buildup issues. A lot of forums with these vehicles theorize that the carbon chunks that break off when you use a cleaner causes scoring on the cylinder walls and can lead to oil burning issues.

Based on the evidence presented in this thread I would say most people will never have issues with the carbon buildup during their ownership.
 

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It has 74K. I can't complain too much about the carbon considering that mileage.



Can't say for sure if they were clogged beforehand. I didn't look real close at them before I cleaned them. But I certainly couldn't tell there were 6 little holes when they were covered in carbon like I could after cleaning. I think injector cleaner might still be worthwhile but I don't think I'd pay much for it. I'll probably throw in an occasional bottle of Techron or Gumout fuel system cleaner in the tank but I certainly wouldn't pay a shop to do it.

There was a little bit of "liquified" carbon that sunk to the bottom of the bowl after I removed the injectors. The majority was still on the tips but had turned to gel. I was apprehensive to clean them with a towel on fear that I'd jam it back into the injector so I tried to do it as gently as possible. Then let them soak some more afterward. I figured since I drove it right afterward, that any gelatinous carbon that got forced back in would probably be flushed out with the high pressure of the injector. What I'm really worried about is the possibility that residual material from machining the fuel pump and lines got in the injectors, which no amount of cleaning or solvent would get out. From what I've read, that was a primary reason for some of these injectors failing - metal shavings from machining the lines and/or pump getting in the injectors. Good job Honda 馃槕 But with any luck this solves the problem so I can avoid spending nearly $400 on a set of new injectors.
My non-DI 2005 is going on 200K. Engine purrs. I'm spooked to get one of these DI engines and the idiotic start/stop nonsense. Aside from lousy road noise isolation it's been a great vehicle.
 

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Thanks!
This is something I've been waiting to see. Someone actually doing a proper check on the injectors and valves instead of just changing the injectors to new ones as soon as the fuel system error code comes up.
This clearly proves that Seafoam or the CRC GDI valve cleaner will be beneficial to use regularly, let's say every 20k or 30k miles or so. I think it may help even with the carbon buildup on the injectors. It also shows that injectors will benefit from cleaning occationally. I'll buy a bottle of Redline fuel system cleaner on a yearly basis (I drive about 10k/ year) until I get an error code, after which I will send them for ultrasonic cleaning before changing.

As most of the buildup on the intake valves must come from the oil fog from the crankcase breather (don't know the correct english term), a catch can should be helpful in preventing buildup. For my own part, I have taken all thesesteps, so basically the only thing to keep worrying about is if the injectors are actually faulty from manufacturing, or if the fuel system (pump or line) have metal burrs in them that ends up in the injectors and causing problems.
 

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I have an oil catch can that I used to have installed on my TL, but uninstalled it because it never had anything in it. That car doesn't consume a drop of oil. I might install it on the Pilot at this point.
As much as one wish it to be true, all engines consume oil. Without any addition of any oil between service, your engine can consume anywhere between 0.5qt to 2.0qt, depending on engine operation and viscosity of oil used. So yeah, your older TL may have not dumped much in the catch can, like my G1 Ridgeline, but trust me, they all consume oil.

Here is a link to my Oil Catch can in my Odyssey that uses the same engine as the current gen Pilot. 2018+ Odyssey - Oil Catch Can

Comparing my G1 Ridgeline and my G5 Odyssey (having the same displacement), I had 12-times more blowby in the can that is on my Odyssey. So the DI engines do seem to have more blowby than the port-injected engines. My Ridgeline (237K mi) consumes around 0.75 ~ 1.0qt between oil changes, while my Odyssey (38K) consumes approx 0.5qts.
 

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I picked up a 2016 EX-L RES a couple weeks ago (from this thread: Considering a 2016 EX-L. Any suggestions, problems, etc. to look out for?)

Right away it had the emissions light on, presumably from injector problems. The front bank specifically, which seems to be the more problematic of the two. Anyways, I wasn't too excited to replace the injectors since they're pricey, so instead I ended up cleaning them since I was tearing apart the intake to clean the valves anyways, so it wasn't that much more work.

I was surprised that the valves weren't worse but apparently Honda's don't get quite as gummed up as some of the Hyundai's and VW's. Here's what I saw when I cracked it open:

View attachment 134561 View attachment 134562

At first I didn't think they looked all that bad. But once I started to clean them I could see that the carbon was a little thicker than it looked. I used carb cleaner initially, then Seafoam. I've got to say, that Seafoam worked a lot better than I thought it would. I have a new found appreciation for it.

After carb cleaner, then after Seafoam. I used a little pick after that to get out some of the chunks. Between the carb and seafoam, the carbon turned into kind of a gel.

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I let both the carb cleaner and seafoam sit for a while on the valves. After I saw how well the seafoam worked, I let it sit quite a while longer while I worked on the injectors. In order to clean them all, I had to turn the crank so that the valves were closed of course, so I wasn't able to clean all of them at the same time. I used the pick several times to try to grab the big globs. They weren't spit shined when I was done but way way better than before.

As far as the injectors:

View attachment 134567

I didn't want to force the carbon back into the injector so I let them take a nice little bath in seafoam.

View attachment 134568

After that I used a nylon brush and microfiber towel to clean them off followed by about another hour soak. They looked pretty darn clean after that. The 6 injector holes were clearly visible and didn't appear clogged after that.

I didn't use a new fuel line when I reinstalled them. I just made sure the lines were aligned with the fuel rails then torqued them on. I turned on the ignition at that point, which primes the fuel pump and let it sit there for about 10 minutes, monitoring the connections to make sure there was no leaking. I loosened up the line a bit to make sure the pump was initiated and sure enough, fuel sprayed out pretty hard. So yeah, it was definitely under pressure at that point. Again, tightened them up and monitored for another 10 minutes to make sure it was kosher. I took it for a drive this morning, after all the residual fuel evaporated then smelled the engine bay afterward to make sure there was no scent of gasoline. So far so good.

It's too early to tell if the light will come back on. The fuel trims are still adjusting so I can't rely 100% on the data just yet. I'll also be replacing the spark plugs with NGK Rutheniums and installing new Denso O2 upstream A/F sensors. I have those ready to go and was going to do it last night but decided to do some of these items piecemeal. I'm getting the VCMtuner in the mail today. I also did a single drain/refill of the ATF. It drained nearly an entire gallon. I filled it back up with Valvoline Maxlife. That stuff works great in the TL so I figured it would work in the Pilot. So far so good. I don't notice any difference in shifting but it was already pretty smooth to being with. I'll be doing two more over the next few days. I don't trust Honda automatic transmissions further than I can throw them so I keep the fluid shiny clean. So far my TL has 255K miles and still shifts like butter. I do a drain/refill on that one every other oil change.

If the problems persist after I'm done with the other work, new injectors might be the only solution. We'll see.

That's the progress so far :D
That is impressive. I was considering that and was told about Seafoam but also a simpler approach to try first. My 2010 Pilot only had 96,000 miles and initially got 21-22 MPG with one person in the car. Then within a few months the gas mileage went down and then the engine light came on. I pulled out the spark plugs just as an easy check. I've always had American cars and expected a flat straight electrode so when I saw the pointed ones I thought they were worn. I also noted the #1 plug was carboned up and had the wrong gap of only 0.027" not 0.044" factory or 0.042" NKG made for Auto Parts Stores. The engine light went out. However a few months later the engine light came on again and the MPG was going down. The next easier approach to try was to add Lucas Injector cleaner & Lubricant. For economy sake buy by the pint and add only 3 ounces per fill up. Lines on the side of the bottle and a small pointed tip make it easy to add only 3 ounces. I started with Mobile 89 Octane. I expected a week to clean but within 4-5 days the engine light went out. Next I experimented with alternating between 87 and 89 and other gas companies that are closer to where I live. With the 89 I can go several fill-ups without adding the Lucas injector cleaner. Engine light came on but this time I noticed the gas cap was hard to turn and would click only once. So I experimented and held the gas cap upside down and sprayed inside the gas cap with WD40. Afterwards it would easily click lock three times. After two days of spraying the gas cap the engine light went out. Last ski trip added the Lucas injector cleaner and got 22 MPG with two people in the car. Injectors are getting better all the time.
 

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That is impressive. I was considering that and was told about Seafoam but also a simpler approach to try first. My 2010 Pilot only had 96,000 miles and initially got 21-22 MPG with one person in the car. Then within a few months the gas mileage went down and then the engine light came on. I pulled out the spark plugs just as an easy check. I've always had American cars and expected a flat straight electrode so when I saw the pointed ones I thought they were worn. I also noted the #1 plug was carboned up and had the wrong gap of only 0.027" not 0.044" factory or 0.042" NKG made for Auto Parts Stores. The engine light went out. However a few months later the engine light came on again and the MPG was going down. The next easier approach to try was to add Lucas Injector cleaner & Lubricant. For economy sake buy by the pint and add only 3 ounces per fill up. Lines on the side of the bottle and a small pointed tip make it easy to add only 3 ounces. I started with Mobile 89 Octane. I expected a week to clean but within 4-5 days the engine light went out. Next I experimented with alternating between 87 and 89 and other gas companies that are closer to where I live. With the 89 I can go several fill-ups without adding the Lucas injector cleaner. Engine light came on but this time I noticed the gas cap was hard to turn and would click only once. So I experimented and held the gas cap upside down and sprayed inside the gas cap with WD40. Afterwards it would easily click lock three times. After two days of spraying the gas cap the engine light went out. Last ski trip added the Lucas injector cleaner and got 22 MPG with two people in the car. Injectors are getting better all the time.
The 3-click fill cap requirement was the first thing the salesguy taught us back in '05 when we purchased ours.
 

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Anyone had O2 sensor issues after using Seafoam or other Intake/ Injector cleaner?

Im at 12k miles on my Pilot and I'm considering running a can of Seafoam around 15k but was thinking I should change the oil soon after. Probably try to do it every 15-20k miles to keep the tops clean.

I prefer to get ahead of any headaches.

Edited to add:
My daily commute is probably 10-15 miles at low speed (city driving) but on the weekend I try to get out on the highway.
 

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Thanks, they didn't tell me that and the manual just says to make sure it is tight. It seemed very tight to turn but barely clicked once. Now after the WD-40 it is easy to turn and easily clicks 3 times. This is my first Honda so still learning the quirks, like no tranny oil fill and no easy way to change the tranny oil. Scary cost reduction. Because of that probably be my last Honda.
 

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Thanks, they didn't tell me that and the manual just says to make sure it is tight. It seemed very tight to turn but barely clicked once. Now after the WD-40 it is easy to turn and easily clicks 3 times. This is my first Honda so still learning the quirks, like no tranny oil fill and no easy way to change the tranny oil. Scary cost reduction. Because of that probably be my last Honda.
What year Pilot are you talking about here, still the 2010?? The 3rd generations (2016-2020) have no fuel cap.

The 6 speed transmissions are very easy to change the fluid and filter and fill. The 9 speed can be done easily also but not if you follow the Honda listed procedure.
 

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Comparing my G1 Ridgeline and my G5 Odyssey (having the same displacement), I had 12-times more blowby in the can that is on my Odyssey. So the DI engines do seem to have more blowby than the port-injected engines. My Ridgeline (237K mi) consumes around 0.75 ~ 1.0qt between oil changes, while my Odyssey (38K) consumes approx 0.5qts.
I recently installed on catch can on my 2016 Pilot, after having fuel injectors replaced at 60K miles. Never used a catch can before, and wasn't sure what to expect but I was shocked when I checked it after less than 500 miles.
134800

Probably 8-10ml of junk in there in less than 500 miles (fresh synthetic oil as well).

Huge thanks to the OP for helping provide some clarity and hard evidence on the issues with the Honda 3.5L DI engine. Glad to see the Honda motor it isn't as bad as some of the older DI horror stories.
 

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I thin
What year Pilot are you talking about here, still the 2010?? The 3rd generations (2016-2020) have no fuel cap.

The 6 speed transmissions are very easy to change the fluid and filter and fill. The 9 speed can be done easily also but not if you follow the Honda listed procedure.
k you have a typo as if you didn't have a fuel cap you'd never be able to buy gas. The injector cleaner goes into the filler tube before you add the gas.
 

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I thin

k you have a typo as if you didn't have a fuel cap you'd never be able to buy gas. The injector cleaner goes into the filler tube before you add the gas.
Many vehicles have done away with the fuel caps for years now! The cars even come with a special funnel to add fuel system cleaner or gas from a can if you run out. The special funnel is needed because of the design of the cap-less fuel filler inlet tube. There is a metal cap which pushes down to allow you to add fuel or additives from a gas nozzle or a gas can or a bottle.
 
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