Most fuels in North America contain sufficient additive packages to keep valve stems clean. DI engines, however, might require more (jury is still out on this one). Top Tier gas should have everything you need.

For years I've used Techron, but most of the dealerships push BG. And then there's Seafoam (used that in the 'pour down the throat method' on an older care once). Who knows....

 

All top tier fuel has additives to clean. Toyota’s implementation of Direct Injection also includes port fuel iNjection as well so the fuel does go over the valves to clean them, unlike other DI systems that don’t have port injection.

 

So how many injectors do we have in the 3rd gen sienna. I would assume 6 DI injectors and those would never touch the valves. How many injectors and where are they located that would spray the fuel to reach the valves (to prevent carbon build up)? Just curious

 

Up thru 2016 (2GR-FE engine) = 1 port injector per cylinder.

2017 FKS variant (Atkinson Cycle) has dual injectors per cylinder (port and DI).

 

Here’s a good explanation of the Toyota D4-S system.

 

Here’s a good explanation of the Toyota D4-S system.

Thank you that was the perfect video to help me understand how it works. This makes a lot more sense that they have one injector in the air intake to help wash over the valves to help avoid carbon build up. Thats a common issue for my 2008 bmw 335xi n54 motor.

 

Yeah, Toyota’s design prevents carbon build up.

 

We HOPE that there is sufficient fuel flow from the port injector to PREVENT carbon deposit build-up, and not just SLOW the build-up. That's why I say time will tell.....

 

Well, the D-4S system has been in use by Toyota since 2007 I believe roughly 13 years, should be enough time to hear about carbon issues if there were any.

 

If you look deep enough into the tech docs, you will see critical differences in use and dwell time of each injector in relationship to RPM, load, operating temperature, etc. Sometimes one is favored over the other, sometimes they both run. Each engine's operation is different, as is the vehicle application. Each combo carries a unique mapping.

That says to me that the eventual outcome of this near identical powertrain applied to the Highlander and Sienna could be different.

Engineering is all about sweating the details.....

 

That is correct, and you are right in that each application is different, even down to the level of how each driver uses their vehicles. But since the system has been in place for about 13 years across vastly different vehicle types which would encompass vast driving dynamics differences, I would expect that within this time, if there was a carbon buildup issue similar to the way the Germans have developed their DI systems, it would have surfaced by now. But that is just an assumption on my part.

 

By design with at least partial flow over the valve stem, the Toyota system seems inherently better in terms of resisting carbon deposit buildup. And the data reports so far, within the limits of sample size and vocal people actually screaming out loud about it, does seem to support that it is indeed better. No question about that. It's not the outright disaster that some GDI systems have become. But call me guardedly optimistic. I don't think we've seen sufficient data yet to say that it isn't happening at a reduced level.

Remember that an engine can run acceptably well with an awful amount of crud buildup thanks to adaptive mixture regulation. Fuel trims could be up several points, and 99.9% of drivers will never be the wiser.

 

Just run top tier gas and you'll be fine. I personally stick with Chevron for all my vehicles. I'm not sure if Toyota's D4S experiences LSPI, but if it does, then use an oil that prevents LSPI like Pennzoil Ultra Platinum or Amsoil.

 

As the initial responder said, Techron fuel system cleaner does a great job of cleaning out the system. Redline fuel system treatment is also good, but is only found at Pep Boys or online. Both have the same active ingredient whose name I cannot recall. Just pour some in your gas a few times a year.

 

Be certain to have a tech do a TBI throttle body intake maintenance biennially or so. Performance/fuel economy is the bennie.😁👍

 

I started using Marvel Mystery Oil back in the 50’s at Fairbanks Alaska, I’ve gotten into a habit of still using it today, I just put some in the gas as directed, I have never had an engine problem with any of my autos. My present 2008 Sienna purrs like a kitten.