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370cc Injectors from the 92-94 EJ22T CAN be swapped into the 90-91 N/A rails, they're the same injectors; just different flow rates.

However, the N/A computer tries to drive them too hard (open them too long); result? fuel sprays out the exhaust engine barely idles. Just incase anyone thought of trying it: don't bother, I did; doesn't work.

The only good thing that came of it was I found an exhaust leak... You can guess how.

A ghetto trick to trim fuel would be to lower the base fuel pressure - which is how I run big injectors on my '99 phaseII OBDII Impreza.

A 25psi base on 370's will give you 280's which the ECU should be able to control.
If you are NA you have no need to do this.
Note - base pressures that are too low may lead to bad fuel atomization.

That's good to have some concrete confirmation that EJ22T injectors will drop into 90-91 NA rails, thanks!

Yes, you can't get good results by mixing and matching ECUs and injectors that aren't meant to work together. As a point of curiosity, though, the ECU will actually eventually learn to lean it out quite a bit to the point where it will idle. While developing my scan tool I actually ran my EJ22T on a variety of non-turbo ECUs.

If the only injectors you have are the wrong size, then, like BXSS says, you can mess with fuel pressure to get them to flow more or less the right amount.

But if you're trying to get more fuel to support a turbocharger, the best quick-and-easy fix is a rising rate fuel pressure regulator.

that's what I'll have to get, a rising rate FPR until I can afford an Autronic standalone. Where can I find one? brands to use? types? etc. never done research on them yet.

Vikash, did you make your own scan tool? From scratch?

scuzzy - I'm using a Vortech FMU. I don't know the ratio, but it doesn't matter that much; I rigged up a bleed valve thingie to reduce the rise ratio down to just barely above 1:1.

I can certainly recommend the Vortech units from experience, but I'd imagine that they're all pretty much the same as long as they're from a reputable parts manufacturer.

Arctic Assassian - Check out the stickies in the Electrical forum.

They CANNOT be swapped. I suspect that you thought you swapped them, but I bet you are leaking fuel past the 0-rings like a muther fucker.

I ran 370 cc injectors for more than a year on the NA ecu, and NEVER NEVER EVER NEVER leaked fuel. You simply have 4 bad o-rings!

If there is fuel coming out the exhaust, you have more issues than the ECU running a 25% larger injector!

douglas vincent wrote:They CANNOT be swapped. I suspect that you thought you swapped them, but I bet you are leaking fuel past the 0-rings like a muther fucker.

I ran 370 cc injectors for more than a year on the NA ecu, and NEVER NEVER EVER NEVER leaked fuel. You simply have 4 bad o-rings!

If there is fuel coming out the exhaust, you have more issues than the ECU running a 25% larger injector!

Douglas, I respect that you've done a lot of research and tried a lot of different things; but I compared the 370's with the ones I took out and they looked exactly the same, the O rings were in fine shape with no tears or any other problems; they installed fine, it took a little pressure (no more than two thumbs worth) to seat them in the rails just like putting my stockers back in did.

If i was leaking fuel past the o-rings, I would have flooded and locked a cylinder, which I did not do.

The O rings for both the stock EJ22 injectors and the EJ22T injectors were the same size, I even tried swapping them back and forth with no problems.

I'd love to have pictures for you, but I didn't bother to take any, I expected people would take my word for it when I said they fit; because they do fit, they sit just like the stockers do in the rails.

Hell, I had to even reach in and pull the rings out of the rails after I pulled the injectors out, that's how snug they were; it took no more force to put my stockers back in than it took to put the EJ22T ones in.

Now that being said, I believe I recall you saying that you ran some form of piggybacking or somesuch when you were trying this, that being the case I could see why these 370cc's worked just fine for you if you could adjust fueling, or trick the computer into doing it for you.


And last but not least; I wasn't "leaking" fuel into the exhaust, the engine was running so rich that every cylinder didn't always fire, the excess fuel went to the exhaust and seeped past some bad crossover pipe gaskets that I had installed - I went and replaced those today.

EDIT: an important note; I am NOT running the N/A engine with 9.5:1 compression; I'm running the EJ22T engine with 8.0:1 compression; even at idle the ECU settles on about -8 to -10% fuel trim to correct the rich condition. I can see how 370cc's on a 9.5:1 engine would be fine because the ECU is designed for the right compression ratio of the engine already.

I ran the 370s without the PP6 for a year or so.

Of the 370 cc ej22t injectors, I am THINKING of the PINKs. and those I know dont fit. What are you using as the 370 cc?

And yes, pictures are worth a 1000 e-thuggings.

Hold it, did you remove the plastic tips? you mention having to pull out the o-ring......

douglas vincent wrote:Hold it, did you remove the plastic tips? you mention having to pull out the o-ring......

plastic tips? I removed nothing. there's three O rings on the injector. one that seals the bottom of the fuel rail, one that seals the top of the fuel rail (on the top of the injector body) and a third that seals against the intake manifold.

They're the stock freaking side-feed 92-94 Sport Sedan injectors man, pink tops; side feed fuel rails. They fit. I know they fit. I was there. WHEN I FIT THEM.

Sorry. I don't mean to get angry, I'm just frustrated; you're telling me I can't do something I did.

I swear to god. my 1991 Subaru Legacy L Wagon EJ22E Injectors with gray tops side feed at what.. 280cc; look EXACTLY LIKE the injectors that came on the 1992 Subaru Legacy Sport Sedan Turbo engine I bought two years ago and removed from the intake manifold myself with only the following exceptions:

The tops on the Turbo injectors are pink.
The fuel spray port-thingy is obviously larger on the Turbo injectors.


Everything else, from the placement of the O-rings to the size of the electrical connectors, to the width, length, height, and style (no nozzle protruding from the end) are exactly the same, even down to the number of little side-feed screen dealies.

I hit the old ones with a little PB Blaster around the seals and they popped right out, I sprayed the new ones with a little brake component cleaner and they fit right in with minimal pushing.

The O ring that I had to pull out of the rails when I removed the turbo injectors to put my stockers back in was the second to bottom O ring that seals the bottom of the rail to the injector (to prevent fuel from getting into the intake manifold past the injector) all four injectors had that "problem" and all of them were snug in the rail like they should have been.

For what it's worth, I do remember the parts manual indicating that turbo injectors and 90-91 5MT NA injectors use all the same o-rings, and that 91 fuel rails are the same on turbos and non-turbos.

It could be just a damn o-ring malfunction. I have had many a bad o-ring that leaked major fuel in.....

I'm not sure why you would want to do this but an S-AFC seems like the easy way to get a 90NA ecu to run an NA motor with 370CC injectors.


Now, would an EJ25 NA hybrid running from the stock ECU run well with the turbo injectors swapped into place?

Like I said in another thread, the stock ECU and stock injectors will work with an EJ25 NA hybrid better than any hack job mix-and-match. I don't know the flow rates of 90-91 NA injectors, but 92-94 NAs actually used the same injectors and MAF sensors as early EJ25s.

I've never tried to put Ej22T pinks into any other rail than their own rails. And I have never put 90 NA injectors into anything but their own rails. So, I cannot comment on the cross compatibility of such things.

What I can comment on is different injectors with different ECUs. I currently run an EJ20G in my '91SS with an Ej22T ECU. The first time I started it, it idled around 1800rpm. The second time around 1400rpm. The third time around 1400rpm. By the fourth or fifth start after the swap, the car idled like it was stock and runs around 600-700rpm. Not all my adventures have been so simple.

For example, when I put an Ej20g bottom end against Ej22t heads and injectors and ran it against an Ej18 ECU the damned thing was so rich it wouldn't idle. It refused to learn. We installed an Emanage and it still wouldn't pull idle trim enough to make it run right. So, we installed a set of 90 Ej22e injectors and rails along with a RRFPR, and Wala! Thing idled like it was stock. It pulled hard and ran 12psi non-intercooled using the stock EJ22T inlet plumbing. We even ditched the Emanage after that.

The other success was a high compression hybrid. We ran the phase I Ej25 bottom end with ej22e heads. It took a while for the ECU to learn, but it adjusted. At high rpm's we had detonation crackle until we went to 91 octane, but I don't think that was fueling issue as much as a compression ratio issue. Higher octane solved the problem and it was fine...

I mentioned a ghetto trick for trimming fuel from big injectors above, but I did not mention the ghetto trick for squeezing a little more fuel from your stock injectors.

So here it is -

Hose clamping (use a Subaru hose clamp so you do not cut into the hose when you clamp down on it) the return line will increase base fuel pressure as you tighten the clamp down which in turn will get more fuel out of them.
If you do this I suggest "t'ing" a fuel pressure gauge on the fuel feed line so you can measure how much pressure your adding.

Move up in 5psi increments, but do not set base fuel pressure tooo high (do not set base pressure @ some thing crazy like 65-70psi) or you may have problems.

I think most folks will not need to do this, but if you need some more fuel, this is an easy way to get more out of your injectors for the cost of a hose clamp ($1) 5/16" "t" ($2) & a pressure gauge ($10+) which is much cheaper than a after-market fuel pressure regulator (my aeromotive was $135 + the cost of the fittings $25-30).

That is super ghetto. You'll actually get the most enrichment at idle, and the least enrichment at full throttle!

If you're gonna go that ghetto, I'd say to just crush down the cap of your FPR to increase static pressure everywhere.

Yeah it is super ghetto but it works, is adjustable, & can be undone if the need arises.

You will be increasing static fuel pressure by doing this so the extra fuel should be everywhere from idle on up.
I've done this to a few friend's ghetto turbo LOW budget cars & it does help cars that need a smidge more fuel.

what's the point of the vac line that goes to my FPR anyway? there's one on there, I've left it hooked up, but no clue the point to it?

BXSS - But the flow through the return line is greatest at idle and decreases with engine output, so the pressure drop due to the restriction is also greatest at idle.

I'm not arguing that it doesn't work; of course it does. I'm just sayin'.

scuzzy - The vacuum port is the manifold pressure reference. The fuel pressure regulator regulates fuel pressure to 36.3 psi above that reference pressure. That makes the injectors always have 36.3 psi between their inlets and outlets, so their flow is constant. You need that vacuum line.

vrg3 wrote:scuzzy - The vacuum port is the manifold pressure reference. The fuel pressure regulator regulates fuel pressure to 36.3 psi above that reference pressure. That makes the injectors always have 36.3 psi between their inlets and outlets, so their flow is constant. You need that vacuum line.

So you're saying, at my relative air pressure of ~14.50psi, on vac at -20mmHg (20 torr) my intake sees an absolute pressure of about ~14.10psi normally.

Now, adding the FPR's built in regulation feature; my injectors (at idle) see 14.10+36.3 psi = 50.4psi of absolute pressure, is this correct?

if I were to plug a fuel gauge up, would it show 36.3 psi or 50.4 psi?


Furthermore, if I add 5PSI to the mix; my intake pressure is 14.50psi+5 psi=19.5psi; with 36.3psi regulation added to that, does that ramp my fuel pressure to 55.8psi absolute/41.3psi relative or does it remain at 50.4psi absolute/36.3 relative?

I'm wondering if this thing is already a built in rising rate FPR.

I guess it's worth it to also figure out what happens when I add an actual rising rate FPR to the mix; I'm sure you put one in AFTER your current FPR, but what the restriction behind the stock FPR has on the unit? I don't know, that's why I ask.

Let's be precise.

Your atmospheric pressure is 14.5 psia (that's psi absolute).

When your engine is idling, manifold pressure is -20 inHg gauge, or about -9.8 psig (psi gauge), or 4.7 psia. The FPR will regulate fuel rail pressure to 41.0 psia. A fuel pressure gauge would read 26.5 psig.

Now when you're making 5 psi of boost, manifold pressure is 5 psig, or 19.5 psia. The FPR will regulate fuel rail pressure to 55.8 psia, which would read on a gauge as 41.3 psig.

Here's where a lot of people get confused and think this matters. Remember that the injectors are basically valves with calibrated orifices in them. The inlet side of the valve is connected to the fuel rail. The outlet side is connected to the intake manifold. So, the flow rate through the injectors depends only on the fluid properties of the fuel (which we assume to be constant), the size of the orifices (which we assume to be constant), and the differential pressure between the inlet and outlet.

So what differential pressure do the injectors see at idle? 41.0 psi - 4.7 psi = 36.3 psi.

And at 5 psi boost? 55.8 psi - 19.5 psi = 36.3 psi.

See? No difference. Thus, a 5 millisecond injector pulse will flow the same amount of fuel at idle and at 5 psi boost.

An RRFPR actually increases fuel pressure by more than the increase in manifold pressure, so it makes the injectors actually flow more when you're on boost than when you're idling.

The restriction that BXSS is describing just prevents the FPR from properly doing its job; that's all.

vrg3 wrote:Let's be precise.

Your atmospheric pressure is 14.5 psia (that's psi absolute).

When your engine is idling, manifold pressure is -20 inHg gauge, or about -9.8 psig (psi gauge), or 4.7 psia. The FPR will regulate fuel rail pressure to 41.0 psia. A fuel pressure gauge would read 26.5 psig.

Now when you're making 5 psi of boost, manifold pressure is 5 psig, or 19.5 psia. The FPR will regulate fuel rail pressure to 55.8 psia, which would read on a gauge as 41.3 psig.

Here's where a lot of people get confused and think this matters. Remember that the injectors are basically valves with calibrated orifices in them. The inlet side of the valve is connected to the fuel rail. The outlet side is connected to the intake manifold. So, the flow rate through the injectors depends only on the fluid properties of the fuel (which we assume to be constant), the size of the orifices (which we assume to be constant), and the differential pressure between the inlet and outlet.

So what differential pressure do the injectors see at idle? 41.0 psi - 4.7 psi = 36.3 psi.

And at 5 psi boost? 55.8 psi - 19.5 psi = 36.3 psi.

See? No difference. Thus, a 5 millisecond injector pulse will flow the same amount of fuel at idle and at 5 psi boost.

An RRFPR actually increases fuel pressure by more than the increase in manifold pressure, so it makes the injectors actually flow more when you're on boost than when you're idling.

The restriction that BXSS is describing just prevents the FPR from properly doing its job; that's all.

Wow, okay; my numbers were wrong and you're smrt

So disconnecting the vac line from the FPR means the regulator will regulate the fuel pressure to 50.8psia at idle, and 50.8psia on full boost (5psi short of the differential) so the injectors would be flowing LESS under the pressure in the intake manifold because of the differential.