Hi there,
 
  I have a 91 MR2 turbo with ct20b, MBC, 3" downpipe/ exhaust and I wanted to increase the boost a bit so I got a Fuel Cut Defender. And now, I am wondering how safe the FCD is on a stock fuel system from a 91?
I am planning on increasing the boost between 14 and 16psi (whatever is safe on the system I got now). And I am wondering if the fuel system/ pump will be able to handle that? And if it doesn't, what would happen? The FCD should still prevent me from running more boost than the fuel system can handle by cutting the fuel/ boost if I try to boost too high, right? Or should I be looking at upgrading my fuel system even at this level of boost?
 
I ordered a wideband o2 sensor so that I can see what's going on, but even then, I would prefer for the ECU to handle that on its own, rather than having to monitor it myself.
 
I only recently bought my 1st mr2, so I am seeking advice on the experts to make sure I don't do something stupid :)

The stock ECU has maps all the way up to 18psi. You shouldn't really have any issues just upping it to 16psi. At 18psi, you'll be edging towards the upper end of injector duty, so as a safeguard you may want to put in some Gen3 540cc injectors or the Supra 550cc injectors.

Thanks man, that's what I wanted to hear :)

Um, I dont think the gen2 ecu is mapoed to 18psi like the gen3. Afaik it only uses the maps sensor for fuel cut and guage duties. It relies on the afm for fuelling etc.

If you run an fcd it intecepts the map sensor signal and adjusts it so as to trick the ecu into thinking your not running over 12psi.

if the mr2 ecu is anything like the gen2 (st185) ecu then as Dylmrt said, it will be fine. 15 Psi would be my target.

Cheers,
Tim

Yes it will be fine on 16psi, but its not exactly very precisely tuned. Nor can you put 540cc injs in with the stock gen2 ecu.

Youll find the stock ecu will run very rich on WOT anyway so adding extra boost than what the ecu is measuring will just help lean it out.

If you are concerned, put the car on a dyno whilst increasing the boost to confirm air/fuel ratio is acceptable.
 
Might be a good idea to resolve your other issues first before increasing power output.

Yes, thanks. I am planning on installing a wideband o2 sensor and also taking it on a dyno to get a safe boost level.
And you are right, I am definitely trying to fix the other issues first.