EA82 RX Turbo 5th Injector

AndrewT · Post by **AndrewT** » Sat Jan 12, 2008 1:12 pm

Anyone got experience with running a 5th injector on an EA82turbo with factory ECU?

Looks like I have a device which does this. It's a black box with electical circuits in it. It has a vacuum hose and a power input.

I'm guessing what it does is detect when theres high vacuum (when you really nail it) and starts the 5th injector pumping fuel directly down the throttle body.....but I'm really not sure, that's a total guess.

Anyone know any more about this?
Also I'm missing the actual injector, what kind do I need and where exactly does it need to be mounted?

INEEDABEER · Post by **INEEDABEER** » Sat Jan 12, 2008 1:22 pm

They use to put them in rally cars to deal with turbo lag.i think they were mounted before or after the turbo to inject fuel to be ignited by the hot exhaust gasses and keep the turbo spinning.

AndrewT · Post by **AndrewT** » Sat Jan 12, 2008 1:29 pm

ah a kindof primitive antilag system then....

Gannon · Post by **Gannon** » Sat Jan 12, 2008 1:48 pm

You can add a 5th injector, and run it with a variable duty cycle generator which gets its signal from the AFM

That way, the duty cycle and thus the fuel output is increased as engine load/revs/boost increases

AndrewT · Post by **AndrewT** » Sat Jan 12, 2008 2:32 pm

I'll take a closer look at it soon and see if theres a brand or model on this controller box...

julian · Post by **julian** » Sat Jan 12, 2008 5:30 pm

AndrewT wrote: I'm guessing what it does is detect when theres high vacuum (when you really nail it) and starts the 5th injector pumping fuel directly down the throttle body.....but I'm really not sure, that's a total guess.

I am not so sure about this- when you really nail a turbocharged car manifold pressure is positive.
Correct me if I am wrong, but I am pretty sure the factory ECU is programmed to enrich the fuel/air charge when turbo supplies boost to keep cylinder wall temperatures down.
Is a 5th injector really useful in a car running standard boost? I would have thought the stock setup is more than adequate.

Gannon · Post by **Gannon** » Sat Jan 12, 2008 5:51 pm

julian wrote:Is a 5th injector really useful in a car running standard boost? I would have thought the stock setup is more than adequate.

Your quite right, the stock system is adequate for running stock boost levels, even a bit more.

You only really nead a 5th injector of you are planning on running more than 8psi of boost.

You cant just add a 5th injector and turn it on and hope it works, it must be controlled so that the fuel output is proportional to air flow. Any engine will flow twice as much air at 5000rpm than what it does at 2500rpm, and must be fuelled accordingly

AndrewT · Post by **AndrewT** » Sat Jan 12, 2008 8:10 pm

Yeah I think this car may have run high boost in the past but it was certainly still using the original ECU.
It came without an engine but this controller box was still under the dash.

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Sun Jan 13, 2008 9:45 pm

I am going to add a 5th injector to my RX in the near future the switch to activate it is already there in the factory loom, the high boost cut out which usually cuts the engine a 10psi. As that is not in use in mine i am going to use that as the trigger and control it using a Jaycar injector variable duty cycle controller which is programable.

discopotato03 · Post by **discopotato03** » Mon Jan 14, 2008 6:32 pm

Why wouldn't you just run slightly larger injectors ie 280ZX Turbo and use the Digital Fuel Adjuster to trim the mixtures ?

Adding extra single injectors can be a problem because you can't guarantee even fuel distribution between all pots . Those manifolds are designed to duct air rather than an air/fuel mix , they gave you multipoint EFI so that the injectors can squirt into each cylinders individual inlet port .

Cheers A .

Gannon · Post by **Gannon** » Mon Jan 14, 2008 7:31 pm

On the subject of bigger injectors and fuel adjusters

Have a look at this 14point7.com - Ultra Air Fuel Controller

Its has a 255 point adjustable fuel table, is under $100, is programable via USB and works with a 10v MAF,... is seems too prefect

Xtreme_RX · Post by **Xtreme_RX** » Mon Jan 14, 2008 7:32 pm

discopotato03 wrote:Why wouldn't you just run slightly larger injectors ie 280ZX Turbo and use the Digital Fuel Adjuster to trim the mixtures ?

This is what i have done........ 6500Rpm @ 12PSI & its running really rich......