NBs' please help. What to do about fuel?!!?
 

Ok, so, here's the story. I have a custom DSM 14b setup on my 99 NB and it is running fine, that is until it tries to boost. I've come to the conclusion that i'm starving it of fuel and the knock sensor is only doing it's job. I have the EMB with Ignition and Injector harnesses connected and that is the only type of fuel mods I have done so far. I understand completely (in hopes that no one thinks i'm some kind of newb to the turbo world) that I need to upgrade my fuel system more. I also understand that it is a returnless fuel system and an AFPR is out of the question how the car is stock. Has anyone converted our system into a return type system? What are some of you guys' out there running as far as a fuel setup goes? Bigger pumps? Bigger injectors? I've been working on this project trying to get all my custom pieces together for about 6 months now and in my own ignorance, never really did any research on the fuel system upgrades. Please, anyone that can help me out without "newb bashing" me, it would be greatly appriciated! Thanks in advance.

Is this something that an O2 clamp would help?

Throw something bigger than 240cc injectors in there. the EMB can handle something like 30% larger injectors, so a 330cc injector. That would at least get you to the 180rwhp range. Right now you can really only support 130rwhp.

I'd also invest in a WBo2 so you don't just think it's starving for fuel and you know it's starving...

that's what i'm asking. I've never worked with a returnless system

I have a close friend that does dyno tuning with a wide band, but, I don't want to put it on the dyno unless I know everything is right and ready to go. what about fuel pumps? Is that necessary? When it boosts (or tries to boost) it just falls on its face, i'm guessing because the knock sensor is cutting it back?

Both the knock sensor is pulling timing and the stock O2 sensor pulling fuel.. Get the clamp, get a tune and don't boost anymore until you have. The NB injectors are a good for 180rwhp or so (~8psi on your 14b setup).

Can you post a base map?

your running at 60psi, your pump should be perfectly capable of handling that and supply more than enough fuel.

the pump has nothign to do with fuel, only if the injectors will be supplied enough or not.

so lets take that out of the equation.

next step is the injectors...currently they are 240cc, which run at 265cc or so at 60psi. that's good for about 130rwhp. I can see the knock sensor cutting you back as soon as you hit around 1-2psi.

if you throw in 330cc injectors and run them at 60psi they will be running at 387cc or so. that's good for 180rwhp.

just throw in a EMB doesn't mean anythign if your injectors still cannot support a given BHP.

change your EMB to an EMU and get some 440 or 550 injectors. screw anything smaller... you want headroom because a) it's safer and b) raising the boost is very very good.

dont eff around with adding a fuel return, it's probably a bigger pain in the ass.

FWIW I have EMU with supra green top 310cc injectors, running ~210rwhp at 12-13afr. That's about the max for these injectors, so get bigger ones if you want any more power.

Can you describe the symptoms, and how much boost are you running?

Assuming yiou are starting off at modest boost levels (say 6psi), I would guess that you need an o2 clamp.

Some dyno (or wideband) tuning is in order before changing fuel injectors, pump etc.

Don't forget the EMB can run additional injectors. So don't be afraid to wire some in. You be amazed at what a pair of 96 lb/hr injectors will do (roughly enough fuel for an extra 300 HP).

Mark

What do I need to do to get an O2 clamp? Does anyone sell them? Also, it's more of a low budget project and EMU is kinda out of the question. I picked up this EMB for like $200. I have a buddy thats trading me some Ford brown tops, which I think are rated @ 370cc. Would these be too big for the EMB? Better yet, will they even fit? I know I have to modify out the harness, but that's no biggy.

Anymore suggestions would be GREATLY appriciated

whats the part numbers You;ll most likely need the clips and wire them in, and if they are low-ohm you'll have to wire in resistors as well.

the EMB should still be able to perfectly handle the 370s.


also consider:

89-92 Toyota Supra 7MGE NA 305cc – Light Green Top #23250-70080
93-95 Toyota Supra 3.0L 312cc - Maroon Top #23250-46030
Toyota 3SGE 315cc – Pink Top
89-91 B2600 Truck 326cc - Gray Top #195500-2150
Mazda 323 GTX TURBO 360cc - Black Top #195500-2130
Celica/MR2 3SGE NA 370cc - Green Top #23250-74160

for plug and play injectors.

YOUR FUEL PUMP WILL BE FINE...as others have said, its your injectors that are too small, id suggest for an easy fix get some 330's in there and retune, with the higher fuel pressure the NB runs they will be great, if you want to push the boundaries a little bit the get some mazda GTX 360cc injectors (red top, also found in toyota 4agze), the 330cc limit is for the old 1600 engine and ecu...im sure the better NB ecu along with an extra 200cc's of engine should make the 360's a good choice.
if you need even more than that then a fifth or sixth injector/s would be a great choice for clutch melting/diff blowing HP.:)

Thanks for all the input/advice guys, and thanks for not treating me like most newbs get bashed!:bigtu:

I sell a clamp for $65. My email is in my profile.

The only problem you might have with fuel is a defective pump. You should really get a fuel pressure gauge wired in to watch it. I have several friends that have replaced pumps in their Mazdaspeeds with the same type system.

Just a note to say that the 323 GTX injectors above are generally regarded as 330cc not 360cc as above.....the red top 323 GTR/4agze are 365cc but are low impedance so youll need a ballast resistor pack to run them.

Ask intelligent questions and you get intelligent answers... go figure!

Mark

go back to the Other Forum, punk!