How to Disable Injector Air Assist

[lhoy12]

Is anybody familiar with disabling the fuel injector air assist on the 5VZ? In my light research it seems to have to do with the IACV. Also what impacts will this have to drivability?

The reason I ask is that I'm getting ready to turbo charge my 4Runner, I can use IS300 550 or 650cc injectors from Deastchwerks, but they told me I need to disable the injector air assist. If anybody has any info on injector air assist, I will greatly appreciate it!

What is an Air Injected Fuel System?

Air-assisted Injection

Prado's air-assisted fuel injection system improves fuel economy, reduces
emissions and better stabilises idling speed. It improves fuel atomisation
by combining an air stream with the fuel at the bi-directional injector
tip. The air-assisted fuel injection system consists of an air bypass pipe
|from the main idle speed control valve (ISCV) to the main injector
nozzles.

The 5VZ-FE engine's electronic control unit controls the air-assist
system, using information from a pressure sensor in the intake manifold.
The air-assisted injection system provides finer fuel misting. It also
allows for fine-tuning of the intake manifold air volume when there is a
large negative pressure in the manifold - such as when the engine is on
over-run.

Why disable a working system?
Most aftermarket fuel injectors are not built to work with air-assist thus the reason to disable.

My Application
For my application, I will be running larger fuel injectors to support a turbo set up being controlled by AEM FIC 6, LCE Performance offers 550cc and 625cc fuel injectors, at time of posting these are $526. On the other hand Deatschwerks offers 550cc and 700cc injectors for $459 and I'm waiting for a quote back later today from MVP Motorsports on their Black Friday pricing. If LCE offers up a Black Friday deal, I will go that route, but if they don't and I can save some money, I will go DWerks and cap off the IACV as well as the T on the back of the engine.

Pics
Pic 1: High level view of the Air Assist Fuel Injection System
Pic 2: Air Injection System is comprise of hose 17341T, 17342L, 17343H, and 17343F
Pic 3: The final pic that looks like just text "Original Post Conclusion" is actually a pic and not inputted text. That is a snippet from somebody who rebuilt their motor, but had misfire and idle issues. It is a good description of how to get to the lower parts of the air injection system.

 

[JayRolla]

Is anybody familiar with disabling the fuel injector air assist on the 5VZ? In my light research it seems to have to do with the IACV. Also what impacts will this have to drivability?

The reason I ask is that I'm getting ready to turbo charge my 4Runner, I can use IS300 550 or 650cc injectors from Deastchwerks, but they told me I need to disable the injector air assist. If anybody has any info on injector air assist, I will greatly appreciate it!

Ive not heard of what your talking about but I do know people have supercharged and turbocharged with larger injectors just adding basic tuning devices. Never heard of having to disable anything on the injector. Maybe try to find larger air assisted injectors?

 

[lhoy12]

Ive not heard of what your talking about but I do know people have supercharged and turbocharged with larger injectors just adding basic tuning devices. Never heard of having to disable anything on the injector. Maybe try to find larger air assisted injectors?

Here is some info on the air assist injection system from the Prado 5VZ:

Air-assisted Injection

Prado's air-assisted fuel injection system improves fuel economy, reduces
emissions and better stabilises idling speed. It improves fuel atomisation
by combining an air stream with the fuel at the bi-directional injector
tip. The air-assisted fuel injection system consists of an air bypass pipe
|from the main idle speed control valve (ISCV) to the main injector
nozzles.

The 5VZ-FE engine's electronic control unit controls the air-assist
system, using information from a pressure sensor in the intake manifold.
The air-assisted injection system provides finer fuel misting. It also
allows for fine-tuning of the intake manifold air volume when there is a
large negative pressure in the manifold - such as when the engine is on
over-run.

 

[JayRolla]

So maybe just disconnect and plug vacuum so the air assist is not more assisting the injector? I do see they have this info for the Prado, did the US 4runners have this assist also.

Im sure the injector companys can let you know how to disable it.

 

[lhoy12]

Ive not heard of what your talking about but I do know people have supercharged and turbocharged with larger injectors just adding basic tuning devices. Never heard of having to disable anything on the injector. Maybe try to find larger air assisted injectors?

LCE Performance has Air Assisted injectors, I'm guessing they're just modified oem 550cc or 625cc injectors for $526, I called to see if they're doing any black Friday deals and they wouldn't tell me. Deastchwerks 550cc or 700cc injectors are $459 before any BF deals and there are a lot of big retailers that sell DWerks injectors so I'm sure I can find additional savings on them somewhere.

 

[lhoy12]

So maybe just disconnect and plug vacuum so the air assist is not more assisting the injector? I do see they have this info for the Prado, did the US 4runners have this assist also.

Im sure the injector companys can let you know how to disable it.

Ours have it also, I found the hose on mine. I'm thinking I can pop the hose off, cap the IACV and put a bolt in the hose and that should take care of it if I cannot find a deal on the Air Assisted injectors from LCE.

 

[phattyduck]

What vehicle is your 5vz in? Is it a US model? I haven't seen this on the US engine... Maybe its T100 only?

-Charlie

 

[Toyotayoda]

Why disable a system that stabilizes idle and better atomizes fuel, seems like a step backward not forward.

 

[lhoy12]

What vehicle is your 5vz in? Is it a US model? I haven't seen this on the US engine... Maybe its T100 only?

-Charlie

I found the hose on my 4Runner,although I can't see where it runs down to once it goes back toward the firewall.i will take a closer look at it tomorrow.

Why disable a system that stabilizes idle and better atomizes fuel, seems like a step backward not forward.

Because there aren't a lot of fuel injector options for running larger injectors. As for fuel economy, its not going to be great with a lifted, fully armored 4runner that is turbocharged.

 

[JayRolla]

Why disable a system that stabilizes idle and better atomizes fuel, seems like a step backward not forward.

Because it gets in the way of his goal of more power!!!

 

[lhoy12]

I seem to have a pretty good grasp on all the routing and information at this point. I will combine everything into the original post just for future reference for anybody else who may have questions or issues with our Air Injection Fuel System.