The Blue Box Unvailed!
 

Okay, just talked with GReddy tech department. This is my understanding of a mystery wrapped inside an enigma: heres the scoop:

GReddy (FCU) Blue box summary:
(FCU is “Fuel Control Management.”)
The stock MAP sensor can actually read up to 12psi of boost, however it has no fuel map provisions for anything over zero pressure. This is where the GReddy FCU comes into play, it provides a fuel map for the ECU from zero pressure up to about 6psi of boost. It also prevents a CEL from coming on with any positive boost pressure readings at the MAP sensor, thereby eliminating the need for check valves or missing link. From 6psi up to 12psi the GReddy FCU still prevents any CELs but it has no fuel map provisions for anything beyond 6psi. This is where secondary fuel management is needed. Over 12psi, secondary fuel management continues to be required, but in reality, the GReddy FCU is not doing anything over 6psi except preventing a CEL. This begs the question, would a CEL come on a over 12psi? GReddy says no, that the FCU will prevent this with no upper limitations. Isn’t that the shit!

Interesting note on my setup: since I am using the missing link on my set up, I am more than likely preventing the MAP sensor from seeing ANYTHING over zero pressure, as a result, the GReddy FCU is not reading anything over zero pressure; as a result, the GReddy blue box is having absolutely NO EFFECT on my setup. Isn’t that interesting!

By taking my missing link OUT, it would then pass on positive pressure to the MAP sensor where the GReddy FCU could read it, and begin providing additional fuel maps to the ECU for zero to 6psi of turbo boost. Then, from 6psi to 12 psi I would further adjust my setup using the VAFC. What allows this fuel management system to work effectively, over 6psi, is the 255 intank pump, the Vortech 10:1 FMU and the VAFC.

I’ll be damn. Here we’ve been giving all kinds of credit to the blue box on my setup (myself included) and theres a good chance its been totally disabled by the missing link. Theres humor in there somewhere. Sometimes you just never know, but (hopefully) learn as you go!

In any event, this means that I shouldn’t take off the missing link until I’m on the dyno again (which will be soon cause I have some other ideas). But then again, I hear the argument if it works dont fix it. The good news is that my setup may have no need for the blue box which would make it available to more people, since the blue box is next to impossible to get.

Whew! Keep it simple? Not with forced induction baby!

Check out post "Back from the Dyno and Happy Again" to get context of this issue.


[Modified by greyzone, 8:18 PM 11/15/2001]


[Modified by greyzone, 5:34 PM 11/16/2001]

Re: The Blue Box Unvailed! (greyzone)
 

Damn, I could've told you that the greddy blue box wasn't doing anything if you had a missing link.. anyway.. I would say ditch the blue box anyway and stick w/ the fmu/v-afc setup. They say the stock map sensor will bust if you hit 12+ lbs of boost, so removing the missing link might be a bad idea if you're looking to push higher boost. I've seen a stock map sensor hold 14psi several times w/o the diaphragm popping, but maybe the guy was lucky. Anyway, removing the missing link is just going to mess everything up imo. It'll run way too rich w/ your current settings. Congrats, those are pretty good #'s w/ the greddy kit. Good luck.

-Mike

Re: The Blue Box Unvailed! (SlowTeg)
 

greddy told me that the blue box also leans out the injectors by 20% in non-boosted driving...in addition to the normal ecu fuel map....also they said it's good to 9psi, 10 psi if you upgrade the fuel pump and increase fuel pressure a bit with an adjustable fp regulator. <96 gsr kit> i've been running .7 bar with no problems...