OBDII PID: "oxygen sensor voltage, short term fuel trim (bank 1 sensor 2)" meaning?
Does it mean that post-cat o2 sensor reading is used to adjust fuel trims?
I have a pc-based scan tool (Elmscan 5 compact USB). It shows this PID data but not the sensor 1 data. Is this normal? Or does it indicate that sensor 1 is dead? Can fuel system goes closed loop with sensor 1 not connected or with bad heater circuit of sensor 1? When the voltage is high above 4.5V, it means rich? What should be the voltage at idle?
I have this high LTFT problem. After reset it increases upto about 11%. Then, next day it goes up to 15%. It goes up faster when its warmed up or the weather is hot. Eventually, after a couple of more days. I get CEL on with P1132 and sometimes with P0141. Could it be caused by a high-flow air filter? I have K&N panel filter. When I drive I don't see smoke in mirror. But I let someone drive my car and I followed it, and saw some black smoke coming out of tail for about a second when hard accelerating. I replaced MAF sensor, but it made no noticeable difference.
In the plot, I was idling first 2 and half second. Engine was already warmed up. Then, dirve around 40 Mph at 1000-1500 rpm, get on the highway 60mph @2000rpm, exit, turn around, and come back.
- Oxygen sensor voltage, short term fuel trim (bank1, sensor 2)
- long term fuel trim - bank 1
- short term fuel trim - bank 1
I only measured three PID in this case for better polling rate
Edit: I got P0137 instead of P0141 today.
Last edited by t5ftw; 09-16-2010 at 08:35 PM.