Fuel Cut Defenders

[scooby491]

hey guys
this may have been asked before but im just cutting to the chase....
fuel cut defenders......
experiences? worth the money? brands/systems? electronic?
also how do they get installed? is it to the ecu?

very mechanically minded so i do as much work myself as possible

[WIDELOAD]

Bad idea. The are wired into the ecu to intercept certain inputs (usually MAF or MAP).
Problem is the engine thinks it's seeing less boost than it really is which mean it will run lean. May end in expensive noises.

[scooby491]

less boost? i was under impression that it came in due to over boost.....

i run an ej20tt in my gen 2 and it cuts at between 7-9 psi..... as far as i can work out from research theyre meant to run 14 psi flat chat

[WIDELOAD]

less boost? i was under impression that it came in due to over boost.....

i run an ej20tt in my gen 2 and it cuts at between 7-9 psi..... as far as i can work out from research theyre meant to run 14 psi flat chat

The FCD makes the ECU 'see' less boost than it's actually getting. eg. ECU 'sees' 7psi when you're actually putting 14psi into it.
Becomes a potential problem because the ECU is giving fuel and timing figures for 7psi. Higher boost you need more fuel or less timing (or both).
That's being pretty broad about it.

It might not be a problem if the factory tune has sufficient headroom in fuel and/or conservative timing. But IMO still not a good idea.

[scooby491]

boost gauge is reading 7-9 psi when it cuts....
gauge is plumbed into intake manifold.

going off what you said though is it possible to be dirty MAF or failing MAP sensor?

[WIDELOAD]

boost gauge is reading 7-9 psi when it cuts....
gauge is plumbed into intake manifold.

going off what you said though is it possible to be dirty MAF or failing MAP sensor?

Not a clue. If it's cutting below what the factory boost level is meant to be there's def an issue. I'd be taking it to someone in the know, there's a few good Subi specialists down in Melb from what I've heard.

[HardwareBoB]

The engine is not seeing boost and fuelling to suit, it is seeing airflow through the afm. An fcd is generally a bad idea, it is a hack around a problem. I ran one on my 180sx back in the day but then I went aftermarket computer.

[scooby491]

ahhhhhk
so suggestion would be to clean maf sensor and stay away from fuel cut defenders. sweet

relatively new to the whole turbo but thing have a fairly in depth knowledge of it

[Robbks]

For an RS an FCD is fine.
however, just run a One Way Valve into the MAP sensor that stops it from seeing boost.
the early ECU uses the MAP sensor for vacuum readings in conjunction with the PE solenoid for fuelling corrections based on altitude.
The only thing it uses boost pressure for is Boost Cut.
As long as you have a boost gauge and a good controller, it's perfectly safe and been done that way for the last 20 years