If this is the case, I don't understand why Toyota is going with this design. This car is supposed to be a "game changer" for Toyota and, I would guess, they are hoping for strong sales. Maybe even Miata-like sales.

Is it possible that Yamaha was brought in to address he carbon build-up issue? Or is the issue simply irremediable?

Sorry to be harping on this one thing. But I'm bugged.

He hasn't owned a sports or high performance car with DI. He does not know that carbon build up on DI is almost 3 times the amount on normal PI vehicles. Unless the manufacturer implements a system to wash away the intake system every couple thousand miles it will continue to build up.*

*Not even BMW has made a system to "wash away" carbon.

Well, my friend, if you put it that way, then it sounds like there is no long-term viability to this design.

So, why are they using it?

(Serious question. I'm not messing with you.)

Since D4S is both port and direct injection, I foresee the carbon build-up problem being less serious, especially since the port injectors will be utilized for the majority of the engine's running time [cruising and idle].

Also, DI is hardly "tried-and-true" on gasoline engines. VW & BMW have had significant teething issues with their HPFP's. The big reason why gas-engine High Pressure Fuel Pump [HPFP]'s are struggling to be reliable is gasoline is a solvent, whereas in Diesel engine's the HPFP is lubricated with Diesel. Thus the inherent design criteria of the HPFP needs to be different.

Has the D4S HPFP been reliable on other Toyota/Lexus models to date?

More pros than cons. Pros are better MPG, power, longer engine life(if no carbon build up) are great and game changing. In reality, the cons are bad for consumers out of warranty. Once warranty is up, you'll have to pay for carbon cleaning every 10-20k miles depending how hard you drive the car. It could be $500 to $1200 to do this cleaning. The cost of parts replacement/installation and maintenance is put onto to the owner of the car.

Only way to not deal with carbon is getting an air/oil seperator system like I linked. You then are only left with cost of parts/labor on the high pressure fuel pump if the pump fails for whatever reason. For the majority of owners who don't know these things is where the problem will lie. Since they will drive it like any other Toyota, fill up and change oil, but that will not be enough and the manufacturer/dealer will not scare them away(more like put in fine print in the manual that will be overlooked or nobody reads).

Yamaha was brought into the mix for performance tuning on the engine, and to make sure their design works within spec to mandated regulations. It doesn't fully take into account reliability of DI system or carbon buildup, although I'm very certain they did look over carbon issues and tried to minimize it. This would require a system built into the head or valve cover to somewhat control the issue better, and would cost lots of money and there are $35k+ cars out there with DI that do not have a preventative system like this because people do not keeps cars long enough or if they do then they should be able to understand "maintenance" cost of things but it's avoidable. So it's remediable but that costs $$ to have standard on every $21k car.

Good info. :thumbsup:



This is what I have been trying to determine.

What a shame.

And, to think, Toyota could have dropped a sweet 200 hp inline-4 in this thing without breaking a sweat.

Everyone on here would agree that an air/oil seperator would fix this issue on port and direct injected cars. Just connect it into the pcv system. The Norrismotorsports is the cheapest system I've found short of using a $20 Lowes tractor air/oil separator that you have to empty out weekly versus the $110 one you can empty between oil changes because it holds more content.

Husky brand @ Lowes

http://www.f150online.com/galleries/...1173-28409.jpg


http://www.mikenorrismotorsports.com...atch_Cans.html

http://www.mikenorrismotorsports.com.../catchcan1.jpg

PA, could you briefly explain, for the non-expert reader, how it works?

Thanks.

Hold on there buddy!

I happen to know I know more than you think. So just hold off on the personal attacks and please refrain from insulting my intelligence.

Thanks,

TheBetterMethod

Basically the air from the PCV valve is routed through that canister, and the turbulence causes the oil to drop out as it flows by (instead of going to the intake to get burnt up, or deposited as carbon deposits).

Around here a lot of the Subaru guys have ones that are actually integrated into the oil cap, so the oil is reclaimed. but that takes a lot more tubing.

Wait, how does oil vapor get into the intake in the first place O_O sorry nub question.
I previously read carbon deposits were due to not fully burned fuel spilling out into the intake on intake stroke, but I guess that doesn't make that much sense.

Taken from
http://www.smokinvette.com/corvettef...70&postcount=4

SHORT VERSION:

Oil Catch Can is designed to effectively separate oil from the crankcase vapors, thereby eliminating all negative effects of excessive intake system oil contamination.

LONG VERSION

The PCV (Positive Crankcase Ventilation) system is designed to regulate and remove fumes from the engine crankcase, and to alleviate crankcase pressure which
could cause oil leaks or seal damage. The PCV system routes crankcase fumes into the intake manifold where they can be burned to eliminate harmful emissions into the atmosphere. The PCV valve controls the amount of crankcase flow volume depending on the engine's load. With large throttle openings (high engine loads),
the more blow-by gases are produced, and the more the PCV system flows oil vapor in to the intake manifold. The PCV valve also functions as a check valve to prevent intake manifold flow from reversing back into the crankcase when there is a backfire, or during periods of high manifold pressure (boost) during forced induction by turbocharger or supercharger.
Negative Effects of your Stock PCV System:
Many owners with LSX engines can testify to the amount of oil residue that can accumulate inside the intake manifold,
throttle body, intake track and even the air filter during aggressive driving conditions.
There are various negative effects when excess oil vapor contaminates the intake
system from the stock PCV system - such as:

*Throttle body and/or MAFS (Mass Air Flow Sensor) malfunction or failure.

*Air filter, intercooler (if equipped) and intake ducting contamination if oil pools and run back out the intake system after engine shutdown.

*Reduced octane of the air/fuel mixture, which can cause detonation and the ECM (Engine Control Module) to retard timing, thereby reducing engine power.

*Excessive carbon build-up on valves, piston crowns, combustion chambers and spark plugs. This also increases the chance of detonation and power loss.

*Increased emissions & possible contamination of catalytic converters and oxygen sensors.