01 Camry o2 sensor behind CAT.

[speedpro81]

What is the purpose of the o2 sensor behind the CAT on a 01 camry 4cyl. I have a exhaust cut out valve welded up after the first o2 sensor and I was wondering if there would be any performance issues when the o2 sensor behind the CAT does not see any exhaust when the exhaust is being bypassed, My Camry is turbo by the way and that was the reason for installing the cut-out valve. Any tips would be great

[chronoti]

it's there for the OBDII, basicaly it checks to make sure the cat is working right.

think you will be fine because it sposta have a lower oxygen count after the cat so no o2 would make it not throw a cel, or it was in the inverse and your going to throw a cel everytime you use the bypass.

[ShawnM]

The purpose of the downstream O2 sensor (the one behind the Cat.) is to monitor the condition of the Cat. The catalytic converter uses up oxygen when working properly, so the computer compares the two O2 sensor readings. The downstream sensor should show almost no voltage when compared to the upstream. The upstream sensor will effect preformance, the downstream sensor will not.

[speedpro81]

Originally Posted by ShawnM

The purpose of the downstream O2 sensor (the one behind the Cat.) is to monitor the condition of the Cat. The catalytic converter uses up oxygen when working properly, so the computer compares the two O2 sensor readings. The downstream sensor should show almost no voltage when compared to the upstream. The upstream sensor will effect preformance, the downstream sensor will not.

One other question, where is the Fuel pressure regulator and how could I up the fuel pressure? I thought the regulator was on the fuel rail with a vacuum line attached. Does trying to trick the computer by making the air intake sensor read a lower temperature reading help with anything performance wise?
I am looking for and trcks or tips on making more power.

[speedpro81]

One other question, where is the Fuel pressure regulator and how could I up the fuel pressure? I thought the regulator was on the fuel rail with a vacuum line attached. Does trying to trick the computer by making the air intake sensor read a lower temperature reading help with anything performance wise?
I am looking for and trcks or tips on making more power.

[ShawnM]

If I remember right the fuel pressure regulator is part of the fuel pump assemble in the tank on your car. There really isnt much you can do with it. Preformance wise, dumping more fuel in isnt gonna make much of a difference unless you get more air in as well. The computers job is to keep everything within certain limits for the best preformance and emissions. Trying to fool it will most likely turn on the check engin light or cause other problems.