Project84

How do I tell my ECU that I have bigger secondary injectors? I asked in the 2nd Gen forum but I just get smart *** remarks. I hate those dick heads. I did a search but the search function is not accurate enough. Anyone with a GSL-SE know?

fatboy7

Well, there is now way of actually telling the ECU that your injectors are bigger than stock, so the duty cycle will remain the same at any given load.

The only thing you can do, is use a piggyback system, like Apexi's S-AFC or equivalent to fool the ECU into thinking that less air is coming in than really is. Less air means less fuel, so you can tune out the over-richness that larger injectors would create.

Supposedly David88vert was in the process of installing a S-AFC, but I don't remember if it worked or not. I've heard conflicting info on this one.... It may not even work on the ECU in the SE.... dunno.

Directfreak

iTrader: (2)

The SE's don't have Secondary Injectors.

Project84

Didn't know that. I have a 87 coupe, thats why I'm asking.

I was wondering if a S-AFC would do it, but apexi's web site was down when I checked (just before I got a shower) and the www.RX7store.net didn't explain as much detail.

RacerX7fb

Why do you have larger injectors in the secondaries?... do you plan on adding forced induction?

speckamp

It's not that simple and unless you have a pervasive reason for THAT much more fuel this is probably not a good idea. Apperantly the 2nd gen (n/a's at least) run on the primaries (the two in the center plate) until ~4000rpm when it then halves the duty cycle and shares the load between both secondary and primary injectors.

A stock-ish 2nd gen can run right up to redline with only one set of injectors (I know someone with a Megasquirt ECU that's currently only driving the primaries while he works on getting staging working) so there's really no need to add more injector capacity unless you're making WAY more power than stock.

If you think about it the turbo ii's only have 550cc/min injectors instead of the NA/s 480cc/min (ish?) That's not a WHOLE lot more capacity when you realize how much margin was built into the fuel system in these cars.

Anyway, if you're set on this, you'll need either a custom chip, an AIC, or a stand alone ECU

But, if you're going to use an AIC, you can't just upsize the secondaries, you'll need to install NEW injectors in NEW bungs with a NEW fuel rail etc, cuz the stock ecu relys on all 4 injectors for fueling. Anything less and you're no longer getting the right fuel for the air in the engine. If you're ok with this then fine, but it won't work like you expect.

--matt

Project84

Its not for the stock engine. The engine in the car now is stock, but this is for the one I'm building in the garage. I have a 6 port made up of turbo rotors, turbo rotor housings, and a turbo center plate, and N/A end plates. I chose all the plates with the largest ports. I originally planned on adding a supercharger, but for now it will be NOS. Maybe later on down the line I will see how difficult it will be to add the turbocharger so I can keep my fuel injection or I may still decide to go carbed and SC. Its for drag racing so I want enough fuel to keep up with all future upgrades so my immediate changes will be a walbro 255lph pump, pressure reg, and injectors. I was thinking of using the GSL-SE stock 680s for primaries, and maybe 1000cc's for secondaries, depending on the amount of NOS. So basically, yeah I want enough fuel to keep up with forced induction.

The Stock NA injectors are 460 and the TII's are 550, but when they hit 3800rpms, they all go into batch fire. The guys in the second gen section said I can use a S-AFC to tune the A/F and what not. I pretty much got it figured out now. Thanks guys.