D4s Injection strategy

Just thinking and wondering if anybody knows. With both forms of fuel injection if in limp mode to shut off one and just run the other in case of emergency. For example a direct injector fails to switch over to port injection to get you out of the woods. Yes I know it is completely possible theoretically however doesToyota or a programmer do it?

 

I doubt it

 

If a severe misfire happens in a cylinder the injectors are cut to that cylinder to prevent excess fuel from fuel washing the cylinders or flooding the converter.

 

The D4S on this truck is mainly for fuel efficiency and emissions strategies. It runs on direct injection but the port injection is used to control combustion temps for catalyst warming and fuel economy.

It cannot effectively run off just port injection for any cylinder. It will shut down the cylinder as mentioned.

The port injection is utilized mainly on cold start, light and medium load. Negating the stupid air pumps that haunt the previous tacos and tundras.

 

A reason they got away from just direct injection is the intake valves were carboning up with no fuel spraying on them. So they went dual injected to solve that problem.

 

Thanks guys.

 

This is the only reason for the port injection.

 

True, and that carbon falls into the combustion chamber causing cylinder wall scoring. This causes blow by as well. There is also a lot of carbon build up on the low tension piston rings in GDI cars. This causes a loss in compression as well. Lost compression = loss of HP.

 

carbon shouldn't build up on d4s

 

No, you are incorrect. It prevents the carbon build up in the first place. Just like the multi-port injection systems.

The problem with most direct injection systems is that there is no port injector behind the valve so it leads to carbon build up.

I cannot speak for the piston rings.

 

You are absolutely correct about the injector - port - behind the valve. I am referring to Direct inj. Not the port inj. engines or the GDI/D4 with a port injector. I understand and know why they - Toyota, have introduced the port injector! And I applaud them! as far as I know they are the only manufacture doing this (Lexus as well). They know there are issues with this technology and addressing it. So not only will there be the carbon build up, which happens on all cars, There will also be oil build up on the valves and intake as well which I'll address shortly. There is just more carbon build up on the direct inj. cars then standard port inj. due to no fuel continually being injected from above the valves. This is why gas companies have CLEANERS in their fuel - Chevron - Techron to deal with the carbon build up and to help keep valves clean as well as the injectors. I deal with this about everyday in my industry. So even with the port inj on the D4's you are still not getting a continual spray from that injector. Even with the port injector on the D4 which is a GDI car the port injector doesn't run continually. So there will still be carbon build up. When that carbon gets built up little chunks can fall off. Where does it go? It goes into the cylinder where it can bounce around and cause scoring on the cylinder walls. Now if it that little chunk doesn't burn up it can find its way through the exhaust and end up in the cat and burn through that as well. Now this hairline scoring along with the carbon build up on the low tension piston rings causes this excessive blow by. So not only do you get loss in compression very early on in GDI cars - D4's but you get oil build up and consumption.

Now on the oil, reason to address oil is this is where a lot of the problem comes from. Got o change oil regularly. If I owned a D4/GDI I would do my best to change every 3k never past 5k and you need to clean the rings with a quality product. These cars will commonly get codes for Lean or miss fire. Oil also controls the timing on these cars going through a very small portal probably no bigger then the size of your ball point pen. So any sludge or build up effects this as well.

If you do not believe me do a compression test with the car at operating temperature when it is new then check it again at lets say 25k-30k and see what the difference is. Check your oil often and if you want go in with a borescope and look at the valves then go into the cylinder and look at the build up on the piston crown and injector tip...if you can find it.

Also do a few google searches:

How oil works in a GDI car
common GDI engine codes
common GDI engine problems...ect

Here is a good article http://www.thetruthaboutcars.com/2012/05/ask-an-engineer-gdi-problems-in-a-nutshell/

 

Do your research. Carbon builds up in all cars makes and models. It will build in the D4 as well. Ill bet you a steak dinner. see my above post.

 

Want me to pull the heads back off my race car? You buy head bolts, gaskets, and dinner.

 

The discussion was about the Toyota Direct Injection with the additional port injection.

I do know a little about fuel injectors I have been working with them for 20+ years.
You are exagerating the issue with the GDI with Port injector system.


Direct Injection on its own has several issues.

 

I thought we were talking about D4's and GDI. And you throw in a race car? We are not talking race cars here, But yes carbon builds on all gas cars! I am not overly familiar with "race cars" as far as carbon build up, and that's such a broad term - race car.

Look i'm not looking to get into a pissing match on who is right or wrong or knows more. I work in the auto industry and see first hand the issues. So if you want to argue forget about it. Im trying to offer up some insight. Take it or leave it, either way it doesn't matter to me.

Good Day

 

I am aware of the topic and the discussion on TOYOTA's Direct Injection with the port injector - the D4. Toyota and Lexus have been using this same technology before the Tacoma. Its still a direct injected motor....No? So unless that port injector runs all the time which I am pretty sure it doesn't (this would defeat the purpose of a GDI technology and gas economy) the problems will arise...I hope I am wrong, but probably not. From my understanding on that it can be turned on by a technician when he connects up for cleaning and diagnostics, and I think it might be turning on at idle? I'll do a little more research. And there is still the issue of the rings and carbon build up in the combustion chamber as well all issues I have seen on every gdi car.

 

you said all models and makes. Still a gen IV chevrolet small block

 

Yes, now not knowing what kind of fuel, or race car or the type of racing and or is it street driven and how often do you tear it down...then yes it will build carbon. Carbon is a by product of gas.

 

shell 93 pump gas on the street. VP C12 or C16 at the track

 

So it is street legal? All the emission controls ect? Yea it will build carbon. Now and a big question mark on the higher octane fuel I would have to see. Not sure on that. But on the 93..yes for sure.