Hi... first post here.

I have been reading a good bit, and I feel like I have a pretty good understanding of how to turbo a 420A "properly".... but I need advice.

I just got a used eclipse 2gnt with a hahn 16g kit on it. I just finished replacing the head gasket, water pump, timing set, etc, and it runs now with the help of some starter fluid to get it going.

It is equipped with yellow injectors, which I've read are most likely 510cc. It has an Apexi AFC Neo hooked up, which I've read is useful in tricking the ECU into pulling some fuel with larger injectors. It also has a variable rising rate regulator to increase the fuel pressure.


I have a wideband installed already, so that is good to go, and a fuel pressure gauge. I have some 4.7v / 4.3v zener diodes on the way to make my own Fuel cut defender, since the one that was on the car before must have been removed or something... MAP wires were twisted and taped :-/ !??!? Also, running forged pistons, so that is good news.

So.. my questions are.. where to begin? I know most people here will say "get a hahn port fueler", or "run megasquirt".... megasquirt is in the plans for sure, but in the meantime I need to get this thing running under minimal boost with what I have so I can justify the additional cost of megasquirt.

So, I plan to pull the vac/boost ref off of the rising rate regulator and set the onset. Right now it comes on way too early, I believe while still under vacuum.

How would you tune this thing in? Where should I be setting the AFC Neo?

Thanks.

So, I re-found the article about the 420a afc neo... I got it all set up. I had it set to air flow mode still instead of pressure, which was putting out 5.20v to the ECU map input.

I got it set up properly now I think, so hopefully it will run a bit better and I can start tuning it in.

The only "tuning" you can do with the Neo is just pull fuel from the injectors while idling.

Edit, unless you do this....
http://www.2gnt.com/index.php?d=SAFC_fuel_Compensation_Based_on_Boost

Yes, that is the main reason for the neo I believe from what I've read... It does work to add/remove fuel in the rest of the vacuum range though doesn't it?

I guess since it is based on RPM not MAP, it can't be consistent since you could be in boost at 4krpm or in vacuum...

Why not just sell the neo and rising rate fpr and what ever else you have thats trIckIng the ecu and use that money and get megasquirt since you can find a MS for a couple hundred dollars.

What are all the problems you have with the car? It won't idle normally? Or what?

If your not in a rush then keep an eye out on craigslist and eBay for some MS units also on the MS forums there's guys all the time selling MS units.
And you will need a 1:1 fpr the stock fpr will be removed. Basically when you run MS you will just need a 1:1 fpr as well as your larger injectors and fuel pump.

Okay... I've read just a bit on 1:1 FPRs. Can someone check my logic?

(These are not statements of fact, but my current understanding that I need feedback on)...

- A stock fuel pressure regulator has a vacuum reference to compensate for the vacuum in the manifold helping to pull fuel from the injector, to keep a static working pressure across all vacuum ranges.

- A 1:1 FPR does the same, but also handles boost levels and raises the working fuel rail pressure to help push against the boost that is pushing against the injectors.

- A rising rate adjustable FPR also gets reference, but actually increases the working fuel pressure at the ratio you set. 2:1 would be 2 fuel psi on the rail for every 1 boost PSI, essentially adding fuel in boost for a given injector duty cycle when the stock ECU is unable to properly handle boost levels. (Or when injectors are under sized to begin with and need some help?)

Assuming my descriptions are close to correct above:

Say at 100% Duty cycle for an injector (or any constant value), will a 1:1 FPR keep the same amount of fuel flowing from -80kPa up to 80kPa? (Full Vac to 'full' boost)?

If that is the case, does the stock FPR just not handle the kPa > 0 (pressures above atmospheric)?

If I'm on track so far.... Can I simply use my Cartech 12:1 adjustable FPR and set it for 1:1, lock it down, and tune the motor with megasquirt?

I knew "full boost" was a confusing term. What I meant was my max boost. Call it 200kpa or so for now, though in reality I'd never go that high with the stock ecu... more like 5psi.

I am not opposed to getting a 1:1, but it is $150, and my current 1:12, though it probably cost that new, I cannot sell it for near that.

I am still not 100% sure why a set pressure of 43.5psi (stock fpr), even in boosted conditions is really a bad thing provided my injectors can provide the fuel needed for the level of boost. (510cc injectors). They are twice as big as stock at least, and since the charged air will be hotter (less dense), less than double fuel will be needed at 200kpa than what is needed at 100kpa.

I think I am still missing some piece to the puzzle. When the ECU can read the boost properly, why does the fuel pressure need to go up if they are rated to flow enough at the stock fuel pressure? I guess the pressure differential comes into play a bit... 43psi - 14.7 psi is not as much flow...

In a forced induction application, the intake manifold becomes pressurized. Therefore, the injectors need to overcome this positive pressure to provide the correct amount of fuel.

Say for example, you are seeing 5psi of boost and 43.5psi fuel pressure at the rail.The effective pressure of the fuel injectors now becomes 38.5psi and they are no longer flowing at 43.5psi. To overcome this problem, a boost referenced fuel pressure regulator can be used.

A boost referenced fuel pressure regulator (BRFPR) senses boost and raises the fuel pressure at a ratio of 1:1 with boost pressure. So in your example of 5psi boost and 43.5psi fuel pressure, the BRFPR raises the fuel pressure 1psi for every 1psi boost to make 48.5psi of fuel pressure at the fuel rail, allowing the injectors to flow 43.5psi (48.5psi fuel pressure @ 5psi boost pressure).

In a return type system, fuel is pumped into the fuel rail and an on-rail regulator restricts the amount of fuel that exits the rail and returns to the fuel tank, keeping the fuel pressure at the rail constant. A BRFPR actually controls the fuel pressure in the fuel rail by restricting more fuel as boost pressure rises, actually raising the rail pressure rather than keeping it constant.

A candle burning on both ends is twice as bright but lasts half as long.

Okay, I think I understand now. Thanks for working through it with me.

So, above it was suggested that I get an Aeromotive 1:1 FPR, but what would be the benefits of one of those vs setting my cartech/vortech 12:1 FMU set at a rate of 1:1?

The car has been parked since I recently found out it has two front right side lower strut mounts, and the one on the left was flipped backwards to let the sway bar mount up still, which ground off the CV joint boot. Who does that? Hopefully I'll get it going soon.

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I see. I'll have to get one when I order my MS setup. I'm excited that they have Tunerstudio dashes running on android now. It used to be $200 for a screen, and you had to put a computer on it, now a $200 tablet (Nexus 7 or something) is all you need for a nice gauge dash.

I have still not really got my fuel tuned in, having gauge problems that I need to track down. (No tach or fuel gauge, probably speedo is out too).

I did get my suspension fixed up and the car is about ready to go back on the ground.

I saw on some video that a guy had the fuel pressure at idle down around 17 or so. Anyone else using a 12:1 with stock ECU and big injectors (510cc), what is your fuel pressure at idle? I forget what I got mine to idle at, but it is still dumping in way too much fuel.

If your using a 12:1 fmu and 510cc injectors then thats why your dumping fuel. Those injectors are too big to use with a 12:1 and stock ecu. A lot of guys run the 12:1 fmu on Stock injectors up to 8psi even though thats pushing it.