Power FC & closed loop

[Oldman]

I have just had a Power FC fitted and tuned in my R33 GTR, and even though the tuner said he would keep it "lean" at cruising revs, it now uses more fuel than on its original computer. Flicking through the menus on the Power FC hand controller, its shows readings for the two O2 sensors. Deeper in the menu there appears to be a setting for O2 and a Japanese character. My questions that someone may be able to answer for me are

1) should both the O2 sensor reading be active with the motor running as only one of mine seems to register ?( a stuffed O2 sensor?)

2) can you set a Power FC to run closed loop and help low throttle cruise consumption?

Any help greatly accepted.

[Beer Baron]

yep, power FC can run in closed loop. there is an option to turn closed loop operation either on or off. both sensor should be reading whenever the engine is running (assuming we are talking about a gtr here) is only one is registering then the other one is stuffed and replacing it should help fuel ecconomy.

[Oldman]

Thanks Richard. Yep a GTR. How and where do you change the setting to closed loop? What effect will only running on one good and onr=e stuffed O2 sensor make?

[Beer Baron]

you need to go into etc menu and choose 02 feedback control. the symbols are like this:

well running with one stuffed sensor will certainly effect fuel consumption as closed loop cruise wouldn't (or shouldn't) be operating properly. you can disable closed loop operation and have your tuner spend some time on the cruise areas of your fuel maps to give a pretty economical result. or just buy a new sensor.

[Cubes]

'leaner' at cruising rev's is fine but you still have to setup the AFR's and ignition at light load.

Care to throw your ignition/fuel map up to see exactly what he has modified? I have a R33 RB26DETT PowerFC base map to compare it to.

[justin911]

hmm im just trying to understand it all.. been searching..

but anyways is closed loop when its not using the load points/values on the ecu ?

like if i had no o2 sensor and my pfc was tuned at all the low points it would be fine ya ?

[Busky2k]

Yeah closed loop only uses the low load 'cells' of the map but I am not sure of the exact specifics.

But yeah the engine will run fine without closed loop. But if its constantly running rich, that means you'll have more carbon deposits in your combustion chamber and anything coming out from it.