Carbon build up around intake valves?
 

Hi I have read alot about carbon build up around intake valves in direct injection engine specially WV and Audi ,and BMW gets alot of issues .
Toyota uses a port and direct injection combo for one to maximize engine performance and to wash of the gases around the intake valves to prevent carbon build up since traditional port fuel injection engines don't have this issue.

My question is to you who has a lot of mileage on they car have you notice any power loss ?
Toyota engines don't seem like to have this reported problem .

Thanks

I haven't had my BRZ long enough for this to become a problem. But regular excursions to redline are said to burn off these deposits. I'm currently testing this theory...

Ah, yes. The old Italian tune up.

Toyota has both direct and port on the same engine. This reduces the risk of buildup.

I work for Lexus and it's a problem on IS250s because of the D4 injection system that uses only direct injection. The FR-S has the D4S injection which means that the set of injectors in the intake take care of cleaning the intake valves while still using the 4 direct injection injectors for performance.

Nice to see they chose to spend the marginal budget on the engine instead of ridiculous stuff like mood lighting.

BTW, nicely useful first post - welcome!

I think I am one of the few that can chime in with visual information. This is an engine with roughly 25k miles. I forget how many miles of ethanol.... A few thousand or so. Half of the vehicle miles were forced induction so lots of power use.

Here is a picture of an exhaust valve, you can see two more in the background. These I believe were the intake valves from Cylinder #1

https://dl.dropboxusercontent.com/u/...4607.small.jpg

Considering I did 360WHP on the dyno right before it blew up I wouldn't see I saw signs of power loss. lol

The pics of those valves looks pretty good.

I had a BMW 135i which has DI, and has the problem of carbon buildup on the intake valves. My car started misfiring, and the dealership had to use a walnut shell type of sandblasting to clean the intake ports and valves. They were REALLY really clogged up with carbon.

The reason is that all DI engines still have EGR (exhaust gas recirculation) systems, where the engine crankcase blow-by is run back through the intake and reburned. Normally on a port injected engine, the gas flowing through the ports and over the valves effectively cleans these parts.

On Direct injection engines, only air, and the oily smoke from the EGR flows over the valves and ports, which are hot, and this smokey oil sticks to the ports and valves and builds up over time.

Our cars have both port, and direct injection, so I don't see us having this issue, but you can eliminate the possibilty of it happening by installing an oil catch can, also known as an air/oil separator.

These pull the oil out of the EGR blow-by, and send basically only air back through the engine. Some OCC's then run the captured oil back into the engine, others catch the oil and need to be emptied periodically,.

Oil catch cans/air-oil separators are relatively cheap and easy to install too, they are a good mod IMO.

Yeah also consider I was on E85 before the tear down so that could be "cleaning" things up a tad bit too. I also was forced induction with no air/oil separator and we found some sludge on the intake ports. I am not the slightest bit worried considering those conditions. I really wasn't burning oil as bad as my S2000 did but moving forward I will have a catch can. I don't think its "required" to keep the engine running fine as the stock engine seems to do enough as is. And the OEM rom uses 50% port @ cruising speeds so you are constantly spraying fuel on the ports which makes the DI issue pretty much non-existant.

if all cars with DI system have carbon buildup, why is it Audi gets most of the bad word of mouth?

They sold DI first.

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Audi, VW, Mini, BMW, all have the carbon buildup issue from DI I believe.

Pretty much any DI car has the potential to have the carbon buildup issue.

Anyone brave enough to use that Sea Foam cleaner? Supposedly works, but looks kinda scary...not sure I'd want to put that in my baby's engine!