Another fuel cut question

[l6u9k6e9]

Hey, i got a 16g set up, running 8lbs on stock injectors with a wallbro 255 Hp fp. This is what happens...

Up untill now i have not laid into the throttle fully with boost, so today i go to race my friends mustang gt and once i hit about 4k rpms the car falls on its face and all you hear is a "trrrrrrrrrrrrrrrrrrr" I was like holy shit! Would a missing link help? I plan on getting bigger injectors and a safc2 but is there anyting i can do for now?

 

[Blitzeclips]

Sounds like a SFMU may be needed for the extra fuel dumping through your injectors when the turbo builds boost.. Im not sure if a missing link would help, if i remember correctly it is only needed for the earlier models of the 2gnt. (95-96) SAFC may help, but it will probably be more effective when you upgrade the injectors.

BTW, I cant find the number for R&K motors because my phone was recently replaced. But ill check it out in the yellow pages and shoot you a PM sometime soon. Also, check out CarV2.com. I HIGHLY reccommend them for any tuning, setup, or install help. Theyre in Delaware as well.

 

[VelocitàPaola]

if i remember correctly it is only needed for the earlier models of the 2gnt. (95-96):

NO! The 95s were the only models that didn't need the missing link. Get an FCD or ML right away, or you'll continue to get fuel cut. Your MAP is telling the ECU there's boost, something it was never designed to deal with, so it's freaking out by cutting the fuel.

 

[Blitzeclips]

vel, youre right. I mixed up what i meant to say.

 

[GSGoinFast]

Hey, i got a 16g set up, running 8lbs on stock injectors with a wallbro 255 Hp fp. This is what happens...

Up untill now i have not laid into the throttle fully with boost, so today i go to race my friends mustang gt and once i hit about 4k rpms the car falls on its face and all you hear is a "trrrrrrrrrrrrrrrrrrr" I was like holy shit! Would a missing link help? I plan on getting bigger injectors and a safc2 but is there anyting i can do for now?

Well your profile says you have a 12:1 FMU so you should be fine on fuel. But you NEED a missing link/FCD to run boost.

 

[l6u9k6e9]

Yes i have the 12:1 fmu installed, i think it was you i talked to on aim about installing it . Would anyone have any pictures as to the install of the missing link? Also how does it work? Is there a write up? Thanks for the helpl!

 

[DSMcrazy3]

I've never installed one, but I'm sure all it is, you unplug, then unbolt the MAP sensor(left side of manifold). remove it, place the nipple of the MAP sensor in the Missing Link then bolt it back up..I'm assuming the filter will already be in place.

I would recommend getting the FCD, or voltage clamp for the MAP sensor, since I've heard some things about the Missing Link not functioning properly..

 

[GSGoinFast]

I've never installed one, but I'm sure all it is, you unplug, then unbolt the MAP sensor(left side of manifold). remove it, place the nipple of the MAP sensor in the Missing Link then bolt it back up..I'm assuming the filter will already be in place.

I would recommend getting the FCD, or voltage clamp for the MAP sensor, since I've heard some things about the Missing Link not functioning properly..

My missing link didnt work right when I installed it either. I had to get a voltage clamp for it.

 

[l6u9k6e9]

voltage clamp?! what is that? how does it work and what does it do? also do i need the missing link along with it or is it in the place of the missing link>?

 

[VelocitàPaola]

voltage clamp?! what is that? how does it work and what does it do? also do i need the missing link along with it or is it in the place of the missing link>?

You use it in place of the ML. It works by limiting the voltage the MAP sensor puts out, which is how the ECU measures intake pressure.

Say the MAP sensor sends a 4.8V signal to the ECU when your car is at 0 mmHg of vacuum. Okay, that's fine, N/T cars are allowed to run at 0 mmHg. But then, at 1 psi of boost and higher, the MAP sends a 5V signal to the ECU, which sends the thing into panic mode. Now you get fuel cut. The voltage clamp keeps the MAP output signal at about 4.8-4.9V to prevent all this.

 

[baxsom]

i had to get rid of my missing link as well,
it ran fine for a while but i started having idle problems and after changing out every sensor in the car i took out the ML and hooked back up my FCD from hahn and problem disappeared


hahn sells them pretty expensive though

i saw a writeup once on how to build your own

 

[VelocitàPaola]

i saw a writeup once on how to build your own

Sure, it's easy. Here's a basic schematic. PM me if anyone wants me to slap one together.

This one is actually adjustable, so it may need a little tuning, but I can do a simple 4.9V one too.

 

[GSGoinFast]

Yes i have the 12:1 fmu installed, i think it was you i talked to on aim about installing it .

Oh yeah, sorry I remember now.

 

[baxsom]

Sure, it's easy. Here's a basic schematic. PM me if anyone wants me to slap one together.

This one is actually adjustable, so it may need a little tuning, but I can do a simple 4.9V one too.

you see to me thats a whole bunch of squiggly lines

 

[Talon ESI-T]

Sure, it's easy. Here's a basic schematic. PM me if anyone wants me to slap one together.

This one is actually adjustable, so it may need a little tuning, but I can do a simple 4.9V one too.

Actually your slightly misinformed.

95's dont require a Missing link or FCD, some 96's wont either. My 96 ran 2 years without one and I never had a problem. When i part it out i will sell the ecu with that info.

The Factory ECU will throw a Map code when it sees more than 4.7v for more than 2 seconds, NOT 4.8v. This is a fact and its how the ECU is designed.

The FCD you posted the schematics too is more complicated than it needs to be. I build mine with a 10turn Pot and 2 diodes. Has worked well for myself and the people who designed it. Note: the FCD is on my 97 not my 96. I have 3 2gnt's.

GSGOINFAST has one of my FCD's as well

I dont think the problem is a lack of FCD, i havent seen a 2gnt hit hard fuel cut like the 4g63's do. Try the FCD first just in case but you may have a spark related issue.

Terry

 

[VelocitàPaola]

The FCD you posted the schematics too is more complicated than it needs to be. I build mine with a 10turn Pot and 2 diodes. Has worked well for myself and the people who designed it.

I thought about a simple pot., but what dissaued me from that notion is the fact that you're adding resistance to the entire MAP range, from 0-4.7V. With a voltage reg. IC, it only cuts the rising voltage out at 4.7V, the rest of the range stays the same - that way no other part of the fuel curve is modified.