car switches between open and closed loop in idle, leans out, no codes thrown...

[assideways*]

SAFC2550cc deatchwerksn62 MAFS

long story short,

at idle, the car switches between open and closed loop modes. when in closed loop, it leans out to where the wideband no longer shows a reading, just says LEAN. i usually have the safc subtract 50% at 800-1200 rpm at low throttle. now, in order for it to idle, i have to subtract about 38% for it to read ~14.7 on the wideband. this happens even with a brand new o2 sensor. at random, the car would pop into open loop mode due to "system faults" according to the scan tool. however, no codes were stored, except for the usual heater malfunction on the Bay 1 Sensor 2 o2 sensor.

here's a thread i started on ka-t.org:

http://www.ka-t.org/forums/vie...94408

any ideas???

thanks in advance..

[S13FX]

no codes were stored, except for the usual heater malfunction on the Bay 1 Sensor 2 o2 sensor.

BINGO,

is that a old code stored or you just haven't fixed it?

There is a whole article about this on the PLX web page I believe.

[assideways*]

no, its a code that pops up every time since i dont have my second o2 sensor plugged in. it doesnt control anything, just monitors the condition of the cat converter (thats not there anymore). in its place is a wideband right now. so the car doesnt see the second o2 sensor and throws the code. the absense of that o2 sensor doesnt change the car's behavior.

[boltun]

I have a similar problem on my Nissan Altima 97. I have a device to connect to laptop and monitor open/close loop etc. When I increase rpm it goes in close loop stays there as rpm decrease to idle and then again goes to open loop. Put a new oxygen sensor today, but still no luck. I did have exhost leak at resonator which I tried to fix with sealant. Idle is smooth in cold weather , but shaking when its hot.

[vancouverbc]

I have a similar problem on my Nissan Altima 97. I have a device to connect to laptop and monitor open/close loop etc. When I increase rpm it goes in close loop stays there as rpm decrease to idle and then again goes to open loop. Put a new oxygen sensor today, but still no luck. I did have exhost leak at resonator which I tried to fix with sealant. Idle is smooth in cold weather , but shaking when its hot.

This might be irrelevant, but that is how the KA24DE(91-98) is supposed to work. The computer ignores the o2 sensor until rpm is over idle rpm. Computer also ignores o2 sensor when engine cold as O2 sensor will read lean when not hot enough. If you have a dirty O2 sensor (happens when you are rich), you will get a lean reading. I put a new O2 sensor in and it got dirty in a few hours and was back to reading lean.