True...there are several DIY's to do this. See, the hard part, is dumping the contents of the reservoir (crankcase oil). Back in the day (yeah I'm an old fart), the vent tube just exited to underneath the car. That's right, it dripped onto the ground!

Well you know the EPA wouldn't have that, so around the 80's the PCV had to go back into the intake, where it was mixed with the fuel and air, etc...no problem. This trend continued for fuel injection...at least until DI came along. With DI, the fuel charge never touches the valves. Before DI (port inj), the oily mist from the PCV would mix with the fuel before it flowed over the valves...and kept them clean. With a DI engine and normal PCV, that oily mist is still vented to the intake, but now it hits the back side of that hot valve, with no fuel in sight...it pretty much turns to coke. A few exotics of the early adapters of DI, have a "catch can" device that actually clears/drains itself somehow to satisfy EPA. Unfortunately, these early systems had teething problems which scared off the rest from doing it correctly, but expensively $$$!

Now, here's the fix. Install a catch catch with baffles between the crankcase end of the PCV hose, and the intake end of the hose. The steel wool, or whatever is used for baffles, will cause the oily mist to drop out and condense, and only hot air goes back to the intake. Brilliant, right?

Well, here's the catch. The OEM's won't put a factory-installed catch can in the car, because the reservoir must be emptied occasionally...well, maybe even monthly if a pressurized engine (turbo). Now remember this is crankcase oil collecting in the reservoir...you can't just dump that stuff into the trash due to EPA, etc. Hmm, maybe if the OEM's installed the catch cans and put big red instructions in the owner's manual about proper disposal, and 25 pages worth of "your right to know" and why we are so green, etc. Yeah right, you know every consumer is going to dilligently remember to empty their reservoir contents and dispose of it properly in accordance with...

You can see where this is going. Owners will forget/blow off emptying and disposal, reservoir will overflow or malfunction, and oil will get into the environment, etc. Hopefully the Honda engineers have figured out how to vent the crankcase, catch or stop the oil particulates, return them back to the crankcase, and let the remaining hot air back to the intake.

Dang that was long! I think I forgot my meds! Sorry.

 

Many european cars have catch cans (flame traps). The top hoses go to the intake and valve cover. The lower hose vents excess oil back into the pan.

The car is under warrenty. Just drive the thing!

 

Long??? Yeah.

Worth the read??? For me, you betcha!!!

Just keep learning new stuff from guys like you who take the time to write workings of the internal combustion engine. Keep dem posts comin!!!

 

I do agree that it was worth the read. I also do hope that Honda engineered this engine to mitigate the known problems with DI. But then again, they ARE known for their engines since they're an engine company.

 

Mahalo rottboy. Actually, it wouldn't be a bad idea, and it wouldn't hurt anything to add the catch can with baffles to the new DI engine, and then see what's in it after a month. If Honda has done their homework, there won't be anything in it. But if there's two or three teaspoons of oil in it, you probably saved yourself some serious headaches later on.

 

I keep reading that direct injection engines run much leaner than regular engines. During wide open throttle though, I keep recording air/fuel ratios in at 12.0:1. Is this normal for direct injection engines? Why not at least 13.0:1 for power since engine knock and pinging is not that much of a concern with direct injection?

I'm getting these readings from the OBD2 ECU connection.

 

This stuff is awesome and will help out:

Fuel Treatment

 

At wot the mixture is set for maximum power, as much fuel as can be burned completely with the available air.

The fuel system engineers spent hundreds of hours getting this right and I doubt that the existing program is too far off the mark.

Regarding catch cans, I have a feeling that Honda looked long and hard at the problems other makers were having with DI and designed their engines to mitigate them. I doubt that Honda would design a 75,000 mile engine!

If one has a catch can, the solution for what to do with the oil caught is simple, return it to the crankcase!

I don't recommend it for a stock engine, though. Adding one "just in case" is implementing a complicating solution to a problem that probably doesn't exist.

And no, adding snake oil additives is not the solution, no matter how "awesome" someone says they are!

 

A few things. A lean fuel mixture makes more power than rich. It is also more risky in terms of possible engine damage. 14.7 is a "perfect" fuel mixture, a lower number is rich, a higher number means lean. DI engines can run higher compression and also can control the mixture and burn down to the tiniest droplet of fuel so can run more aggressive fuel mixtures without risking damage.

The carbon problem seems to be affecting a bunch of DI engines, though I think boost makes it worse. The DI mini coopers s turbos, VW turbos etc. the VW techs I work with think fuel quality and driving style affect it. They think the people that run 93 octane and beat the hell out of their cars don't have the carbon problem. That is just opinion of course. The way those PCV (mini, vw) systems work doesn't help the problem.

In regards to the Fit DI, it wouldn't scare me to buy one, if it does end being a problem taking the intake manifold off and cleaning the intake ports isn't really that big of a job.

Hope this helps.

 

Until I bought this car, I'd never even heard of "top tier" gasoline. The only gas we have in this area is Mobil/Exxon, Hess, Sunoco and a bunch of off brand convenience stores (the latter two ALL owned by the Mirabito family, which has a virtual monopoly on gas stations around here).


Which of these are "top tier"?

 

I know Mobil and Exxon are top tier.

 

The stoichiometric fuel mixture is 14.7:1.
This would be the mixture of fuel to air that one would use if you could assure that every molecule of fuel was matched to just enough oxygen to allow it to combust. That means that you would have to suspend individual molecules in air, something that doesn't happen since gasoline is a liquid and doesn't atomize completely. The fine, high pressure spray of the DI system does a better job of it than older systems, but it isn't perfect.

Now, for maximum power you want to ensure that every atom of oxygen that the engine can inhale is used since the limiting factor is how much air the engine can get into its cylinders. To do this, you provide a somewhat richer mixture and waste some fuel which is ultimately burned by the catalytic converter. DI systems can use "power mixtures" that are a bit leaner, but even they have to be a bit richer than stoichiometric.

For maximum economy, you want to ensure that every molecule of gasoline is combusted, so the mixture can be on the lean side of stoichiometric to ensure an excess of oxygen. There is a limit, however, as a mixture that is too lean will not sustain combustion and will not burn completely.

Direct injection is better at controlling the mixture, but it's not magic. If it were, the car wouldn't need a catalytic converter!

Oh, and the majority of fuel you buy will meet "Top Tier" specifications even if the retailer doesn't pay to use the trademark. The fact that retailers self-certify their compliance also means that a given tank of fuel you buy may not meet the specifications even though the retailer displays the trademark! Unless you happen to have a analytical chemistry background and are willing to put a few hours into analyzing each fillup you just don't know.

 

Use Google search for top tier. It will list a bunch of them. As stated Exxon and Mobil are both top tier

 

If you can't get top tier fuel in your area add a can of Chevron Techroline (sp?) to you gas tank every 1000 miles to help keep the valves cleaner. FYI the 1000 miles is just a wild guess, that would probably be every 3 tankfuls. Couldn't hurt likely to help some.

 

The only way to fix build up imho?

AMSOIL General Use Dual Remote Oil Bypass Unit

 

It's my understanding the "direct injection" injects the fuel into the cylinder, not the intake tract, so anything added to the fuel cannot prevent deposits on the intake valve stems as the intake valves never see any fuel.

 

Yeah but putting fuel additives or whatever in the tank gives you the illusion of helping your car. Plus the potentially unnecessary purchase of the additive will help spur consumer spending and thereby help the overall economy. Its a win win.

 

Not to mention that snake oil has a distinct possibility of harming the vehicle which means more jobs for mechanics and quicker turnaround of new car sales!

Remember those miracle teflon-laced oils? People thought they were teflon-coating their engines when in reality they were clogging their oil filters and causing oil (and particulates!) to bypass, lowering their oil pressure and increasing wear!

Paranoia is good for the economy!