The secondary O2 sensor does not change the air/fuel ratio. It just monitors the catalytic converter performance.

The primary O2 sensor currently with the P1165 code will change the air/fuel mixture. You need to figure out why you have a P1165 before thinking about the catalytic converter.

 

I got an OBD scanner. Here are some of the numbers. Please let me know what else I should look for.
It gave a same codes P1165 and P0420. P1165 appears under both confirmed and pending codes.

Here is PID snapshot
Bank 1 sensor 1 - 0.77 V
Bank 1 sensor 2 - 0.58 V

Under oxygen sensors
Bank 1 Sensor 1

TID Min Value Max
$31 0.0 0.56 1.84
$81 111 104 143
$83 0 24 78
$84 0 5 83

Bank 1 Sensor2

TID$45 - manufacture defined

min 0.29 value 0.33 max 0.8

 

what are the fuel trim numbers (long and short term)?

 

Short term - 0%
Long term - 3.91%
The car was idling for just a few minutes (< 5 min)

 

The sum of the short and long term fuel trims is how you look at overall fuel trim.

A perfect fuel trim is 0% and means the computer is adding the predicted amount of fuel to the engine. <5% is good. Something is off at 10-20%. Fuel trims change with rpm, load, etc.

The car has to be warmed up for the O2 sensor to affect the fuel trim. This is called closed loop. Your scanner should allow you to see if you are in open or closed loop.

Let us know the fuel trim when idling at closed loop. Make sure your scanner says you are in closed loop. Then hold the gas pedal while parked to about 1500-2000 rpm and report both fuel trims.

 

Here are the new numbers idling under closed loop


Short term - 8.59%
Long term - 3.91%
Engine RPM 2598

I also see another set of fuel trims
Short term fuel trim (Bank 1, sensor 1) - 7.81%
Short term fuel trim (Bank 1, sensor 2) - 8.59%

I see the B1S1 voltage is 0.84 V but B1S2 voltage is 0 V

I can e-mail a report if that is helpful.

Thanks again for the help guys. This is uncharted waters for me.
Dev

 

You should be able to attach a report as a pdf or image on this thread.

I see your engine rpm is at 2598 for the first fuel trims you just posted. Idle should be around 750 rpm, so what were the fuel trims when the engine is at idle at closed loop?

B1S1 is the O2 sensor you replaced. B1S2 is the oxygen sensor in the catalytic converter.

I'm looking up some more information on the type of sensor you have for further testing (a/f sensor, or O2 sensor). I'm going off of tips from a youtube channel called schrodinger's box for my suggestions if you want to watch some of his videos.

 

The sensor you have is a air/fuel sensor. Does your program have an option for equivalence ratio? Does your program plot live data?

 

Here is report @ idling around 700 rpm.
I will checl out the videos you suggested tonight.
Thanks
Dev

 

The intake air temperature (IAT) reading seems high to me at 127F. Also the throttle position sensor at 9.8% seems high too. Take a look at the IAT sensor readings when the engine is cold, key is in the II position, and the engine is NOT running. Do the same for the throttle position sensor and see how the %changes as you push the gas pedal.

Can you post the wire colors going to the TPS and the IAT sensors?