The always and forever fuel cut issue

[radiod]

I've been looking around the board and a couple other places on the web, and I've seen soooooooo many different answers to resolving fuel cut. Basically, I just want to try and get a straight answer out of all this. Here's a couple routes I've seen...

Option A:
Upgrade the fuel pump, upgrade the fuel pressure regulator, mod the AFM (using the screw mod found on these forums), KEEP stock 440 injectors.

Option B:
Lexus AFM, upgrade the fuel pump, upgrade the fuel pressure regulator, 550 injectors

Option C:
(in my mind, this just seems like a recipe for a blown engine disaster)
Fuel Cut Defender

What I'm pretty much trying to figure out is if I need to get 550cc injectors. I know to feed the extra boost, I'll need the pump and regulator upgraded.

Right now I'm hitting fuel cut at ~11-12psi depending on the weather outside. The headgasket's already been replaced, and ARP studs are on, so the engine should be able to take it no problems. I'm aiming for 15psi on a 57-trim CT26. Do I need to worry about doing anything more to the turbo to avoid boost creep or anything?

 

[noah89t]

stay away from the fcd. get the 550s/lexus or maft pro and 550s, get the walbro, of some other fuel pump, and then get a regulator.
i'm running 20psi on a .57 trim, with more mods of course
and to monitor afr's, get a wide band and to tune, get some sort of fuel controller. i also monitor my egt's

there is always more to look at when upgrading one thing.

 

[radiod]

550s are gonna be necessary to get me up to 15psi? I just don't really want to do that unless for sure necessary because of the freaking AirCare regulations we have up here . Curse AirCare!

 

[noah89t]

i am not sure about the limits of the 440's, maybe someone will chime in on that

 

[GrimJack]

Ok, a few things to add.

Don't worry about the 550's with regard to aircare, mine passes perfectly every year.

To defeat fuel cut, without replacing the stock ECU, you need some system that feeds the ECU a smaller signal than it is expecting. This can be accomplished many ways - SAFC, MAFT / MAFT Pro, Lexus AFM, HKS VPC, etc, etc.

To keep this from damagine your engine, you need to compensate for this somehow - otherwise you are just running the engine leaner, which risks detonation or high enough combustion temps to melt important bits, like pistons. Thus the upgraded fuel system - bigger injectors, better FPR, stronger fuel pump.

You *can* make it work without all the extra parts, but it's finicky and prone to breakdown. For instance, for the cheapest route, you could crank up the boost, then pull off the pcv input at the accordian hose and replace it with an air filter, letting unmetered air flow into the turbo. You might have enough top end room in the stock fuel system to handle this. Then again, you might not, and the only ways to find out are on the dyno or run it 'till it breaks.

In my opinion, the route to go is this:
- MAFT Pro, including the MAP option.
- 550s, FPR, Fuel pump, J-tube bypass.
- Wideband sensor, wired into the MAFT Pro
- Ditch the stock AFM entirely

Then visit a dyno and get them to tune your setup based on wideband / egt / knock output.

 

[radiod]

Mmkay, sounds good. Call me ignorant, but what's MAFT Pro. Know everything else .

Last thing I want to do is blow up my engine from running lean. I'm not afraid to spend money, I just want to spend money where it's not needed. At the same time, cutting corners is out of the question.

Dyno run should be pretty easy to get down and do. I've got a buddy who races the street course in Mission and has a bunch of dyno coupons from race wins .

Thanks with the AirCare too....that's one thing I figured could possibly be a real big pain to get around >.< Looks like I'll just have to do my exhaust swap .

 

[GrimJack]

MAFT Pro... geez, it's almost easier to tell you what it DOESN'T do. I keep expecting them to add an option to make toast.

MAFT stands for Mass Air Flow Translator - so it take a different air measuring sensor type, and translates the output from it into a frequency that our ECU can accept as an input.

So, it allows you to ditch your old fragile AFM style air measuring device, and move to a hotwire MAF sensor, or a MAP pressure / temp sensor combo.

At the same time, it allows you to manipulate this signal - so it doubles as a fuel computer, this is essentially how all the AFC style devices work.

Add in the fact that it can monitor and modify timing, can run as an electronic boost controller, hooked up to a wideband AF sensor it can automatically adjust fuel delivery on the fly for wide open throttle, afterstart fuel enrichment, adjust for any size injectors, adjust for water or meth injection, connects to a laptop to load / save as many fuel maps as you want, and I hear the next software update will give random tips on keeping your wife content AND tucks your kids into bed every night.

You're reasonably local, if you are going to end up in Richmond / Vancouver, let me know and you can have a look at mine.

 

[radiod]

Ok, checked into the MAFT Pro stuff and it looks pretty much amazing. Just a quick question on that though. They've got the MAFT Pro and then the vehicle specific MAFT. You need both or is the MAFT Pro standalone?

 

[MK3Brent]

The stock equipment at wide open throttle will go extremely rich.

With just an S-AFC pulling correction will get around FCO for the 15psi you want.

 

[GrimJack]

Ok, checked into the MAFT Pro stuff and it looks pretty much amazing. Just a quick question on that though. They've got the MAFT Pro and then the vehicle specific MAFT. You need both or is the MAFT Pro standalone?

They are independant products, you do *not* need both. As a matter of fact, it would be quite the challenge to try to run both.