i need some help understanding this. AFTER the fcd prevents fuel cut, has anyone figured out what really happens that makes detonation. is it a matter of incorrect amount of fuel (requiring the safc), or is it a matter of ignition time'ing? if its ignition.. doesnt MSD make a box that will help you with that.. the digital-6 or something? ive searched on this but cant find a directly relative subject.

 

nevermind, im blind, i just found the thread on the main page relative to it..

 

the FCD cuts off the signal to the ECU so the ECU never sees over 8psi of boost.

so if you are running 9, 10, 12, 15 etc PSI. the ecu still thinks you are running 8psi and adds enough fuel for 8psi and retards the timming enough for 8 psi.

because the stock map is so rich and conservative you can saftly run around 10psi (with the ecu thinking it's still 8) and it'll still be ok.

SAFC won't add more fuel. it's only good for taking it away (after adding bigger injectors) if you need to put the Safc into the +% then your injectors are too small.

 

Scott,

Its the popular consensus, that the ECU quits adding fuel at like 2 or 3 PSI (using the boost sensor). Then it relies on other things (IE timing, etc...)

Jarrett

 

how far is the timing good for?

EDIT: i.e. the stock computer will adjust timing for boost until X psi

 

Lack of ignition retard.

 

is the msd box the answer to that?

 

The stock ignition timing map are conservative.  Even with the supression of the boost sensor with the FCD, the ignition timing values are safe, as long as you're getting adequate fuel.  An upgrade fuel pump is highly recommend prior to the FCD install anyways.

I think you're getting paranoid about this problem.

Also, see my analysis on Henrik's data dump on the boost sensor relavance to the fuel delivery.


-Ted

 

what does the t2 ecu run for timing at 8psi?

 

what happens if you boost 15psi though.. and you have the fuel to back it up.. what kinda timing scenario is gonna happen there?

 

It would seem so, but what do I know.
Excess fuel delivery is a safer, quicker reacting, and more consistant measure to prevent detonation though.. thats probably why S-AFC's are used.

 

About 15 to 18 degrees total advance.


-Ted

 

That's why I don't recommend that kinda boost with the FCD.


-Ted