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Carbon issues with direct injection engines

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I've got a 2014 Accord which is the first generation with a 4 cylinder DI motor. It's a great engine - very punchy for just a base 4 cylinder. Honda was late to the game with direct injection. I'm hoping they were able to learn some lessons from the other manufacturers...
 
I kinda assumed that I would need to get the engine in the vette walnut blasted eventually. Honestly though, I'll probably pick up a catch can and stick a scope down there periodically. If it gets bad that's an excuse to pull the heads and have them ported... which is an excuse to get a new cam... which is an excuse to get new valves and springs... which is an excuse... well it all ends up with a 427ci LT1 and lots of boost....

$500 seems very reasonable for blasting the intake valve area. It's not a hard procedure, just time consuming. I doubt that it would be very difficult to DIY if you had a media blaster. Shit I have a 50lb bag of walnut media in the basement (but it's larger stuff for tumbling not for blasting).
 
I am left wondering why manufacturers would take a step backwards with a problematic system like DI. It seems like carbon build up is a drawback for this system.
 
silicon said:
I am left wondering why manufacturers would take a step backwards with a problematic system like DI. It seems like carbon build up is a drawback for this system.
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Main reasons are at part load improved fuel consumption, higher peak power output and reduced NOx at low load and idle. With governments all around the globe really clamping down on fuel consumption and NOx, the manufacturers are being heavily pushed towards DI.

Disadvantages are intake valve carbon build up and particulate emissions. Upcoming particulate standards for GDI engines, are likely to mean that gasoline particulate filters will be required before 2020.
 
Oh great, this crap again. I thought I had seen it all over at the F150 forums but I guess not. At least with the F-150 (and other turbo engines AFAIK) if you don't drive it like a grandma, this isn't much of an issue. Any engine is going to suffer from some build up over time. The problem is with people who don't know how to drive and treat the gas pedal like its a carton of eggs. You have to get on it from time to time which helps clear things out. I love it when I hop on the freeway sometimes and literally leave everyone in a cloud of smoke.

Also Seafoam, as has been said, doesn't do anything to fix this. In the case of turbos, its a big no go as well. Instead of black smoke that lets you know carbon deposits are coming out of your exhaust, you'll end up with a nice white smoke that lets you know your turbos are about to shoot out of your exhaust.

There is nothing wrong with DI engines.

Edit: For some engines a catch can is nothing more than snake oil. Its not going to do anything to prevent what it says other than drain money from your pockets.
 
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Given the supposed source of the filth, I would think that driving it "like you just stole it" would make it worse, not better?
 
LTC8K6 said:
Given the supposed source of the filth, I would think that driving it "like you just stole it" would make it worse, not better?
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If it's creating deposits from overlap in the combustion cycle then I wouldn't think driving hard would help much if any. In a variocam motor there might be less overlap at high RPM than low or vice versa but I don't see that being significant. Though thoroughly "using" a motor is always a good thing. 🙂
 
xBiffx said:
Instead of black smoke that lets you know carbon deposits are coming out of your exhaust, you'll end up with a nice white smoke that lets you know your turbos are about to shoot out of your exhaust.
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Seafoam treatment makes white smoke ime. Billowing clouds sometimes, might be that the couple dozen old cars I've used it on over the years weren't sufficiently carbon'd up to produce black smoke, but I would be surprised if that were the case. Google "seafoam smoke" for amusing photos and vids. It's no worse for a turbo that isn't spinning especially fast (stationary vehicle/no load or boost) than it is for a valve or for a cat converter that I can tell. I've run that stuff through dozens of old tired turbo motors that boosted for years just fine after. Saab's and Volvo's mostly. But maybe they were all unusually clear of carbon to start with.
I don't really believe that, but it's' possible.
 
silicon said:
I am left wondering why manufacturers would take a step backwards with a problematic system like DI. It seems like carbon build up is a drawback for this system.
Click to expand...


Not all DI have these problems. Its mostly just European cars and the 2.5 Toyota motor I have seen. I think Toyota said they believe they fixed the problem with the 2.5 motors but still early to tell. The 3.5 motor option does not have the DI problem as its dual inject so spend a little extra now not only for reliability but also better power/resell.
Outside of those there are mostly only sporadic complaints.
 
xBiffx said:
At least with the F-150 (and other turbo engines AFAIK) if you don't drive it like a grandma, this isn't much of an issue. Any engine is going to suffer from some build up over time. The problem is with people who don't know how to drive and treat the gas pedal like its a carton of eggs. You have to get on it from time to time which helps clear things out. I love it when I hop on the freeway sometimes and literally leave everyone in a cloud of smoke.
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I'm pretty sure owners of sporty/performance cars like the VW GTI, BMW 335i, and Audi RS5 aren't driving them like grandmas all the time, and yet those DI engines still have a lot of issues with carbon build-up.

"Getting on it" from time to time isn't going to help with a DI engine, because the carbon deposits are located on the back side of the valves, where there is no fuel flow. The only way that would help is if a particular DI engine (like Toyota's V6) had a hybrid setup with a separate set of port injectors.
 
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Jimzz said:
Not all DI have these problems. Its mostly just European cars and the 2.5 Toyota motor I have seen. I think Toyota said they believe they fixed the problem with the 2.5 motors but still early to tell. The 3.5 motor option does not have the DI problem as its dual inject so spend a little extra now not only for reliability but also better power/resell.
Outside of those there are mostly only sporadic complaints.
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What was their solution for the 2.5 motor?
 
996GT2 said:
What was their solution for the 2.5 motor?
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Stiffer piston rings.

The logic is: stiffer rings, better sealing, less blow by, lower crank case pressure, less PCV circulation, less oil spray into intake, less oil deposited on intake valves.
 
Mark R said:
Stiffer piston rings.

The logic is: stiffer rings, better sealing, less blow by, lower crank case pressure, less PCV circulation, less oil spray into intake, less oil deposited on intake valves.
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Seems like such an easy and straightforward solution. If it turns out that it actually works, I wonder why Audi and BMW didn't adopt something similar.
 
996GT2 said:
Seems like such an easy and straightforward solution. If it turns out that it actually works, I wonder why Audi and BMW didn't adopt something similar.
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I read awhile ago that variable cam timing exacerbates the problem by creating situations where the intake valve opens at such a time that there is enough reversion into the valve pocket area to create deposits. I suspect this is part of why software updates can help as well, they are altering the cam timing to some degree. Is my guess anyway.
 
I think a lot of people are working on it.

I seem to have heard that some of the new fords or GMs now have some sort of PCV catch cans/ filter thing - Not sure, not seen one in person.

The lube oil companies are working on new engine oil additives to reduce this, and the API/ACEA/ILSAC are planning to tighten test procedures for GDI intake valve deposits as part of new oil specifications.

There may be some option to tweak cam timing maps to reduce EGR, but as environmental regulations on NOx are only likely to tighten further, it seems unlikely that this would be a long term solution.
 
I want to say that some DI engines *do* now spray fuel on the valves, as an "extra" injector of sorts? The ECM somehow figures out when it's appropriate, and maybe cuts the other one off at the time.

Theoretically the N55 engine has less trouble than the N54 as well, but time will tell. Not sure what BMW changed in this regard (if anything).

Wouldn't Seafoam work to hit the valve if the right kind were sprayed into a vacuum line? I'm not advising this, BTW, just food for thought.
 
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