O2 sensor by pass?

[bumpit2001]

i was also wondering if anybody can help me with an o2 sensor problem, I have to cat on my 99 cx civic because i replace it with a header and 2.5" exhaust with no cat. so i think my o2 sensors isn't reading properly. Is there a way to by pass the o2 sensor because i don't want to get a cat.

[Smoghog]

Originally Posted by bumpit2001

i was also wondering if anybody can help me with an o2 sensor problem, I have to cat on my 99 cx civic because i replace it with a header and 2.5" exhaust with no cat. so i think my o2 sensors isn't reading properly. Is there a way to by pass the o2 sensor because i don't want to get a cat.

Your computer needs an O2 voltage reading from the first one to get the fuel mixture correct. The second one for the monitors.

Your problem is the second O2.
You could provide a consistant .45v to the signal wire for the computer's monitor. You can get a resistor and drop the 12v heater wire to .45v since the wire is there.

Sure you don't want a high flow cat. They are cheap.

Being a smog tech in CA. I would suggest a cat. Try to be legal first, then remove it if you want.

Smoghog

[superbluecivicsi]

you can drive without the secondary just fine. as for smog, its a no go.

[bumpit2001]

ok well when i have the secondary plugged in the car will hesitate under throttle then all of a sudden it will take of, so when i push the gas pedal it won't go for a couple of seconds then it decides to just go. But when i unplug it it doesn't do that at all but then i'm running rich.

[superbluecivicsi]

the seconday has nothing to do with how your engine behaves.

[Smoghog]

Originally Posted by bumpit2001

ok well when i have the secondary plugged in the car will hesitate under throttle then all of a sudden it will take of, so when i push the gas pedal it won't go for a couple of seconds then it decides to just go. But when i unplug it it doesn't do that at all but then i'm running rich.

Is it throwing a code? Probably cat efficiency. I was wrong yesterday when I told you .45v it should be .1v.

Your Second O2 is to check on the cat. After the cat there should very little or none O2. If you are just plugging it in while in the exhaust the sensor is reading alot of O2 because of no cat. This in turn is sending the computer to it's base mode(open loop) and richening is done by the computer settings not the O2.

There you have it.

SH

[superbluecivicsi]

Originally Posted by Smoghog

Is it throwing a code? Probably cat efficiency. I was wrong yesterday when I told you .45v it should be .1v.

Your Second O2 is to check on the cat. After the cat there should very little or none O2. If you are just plugging it in while in the exhaust the sensor is reading alot of O2 because of no cat. This in turn is sending the computer to it's base mode(open loop) and richening is done by the computer settings not the O2.

There you have it.

SH

the secondary does not do anything at all. only the primary o2 sensor will send the ecu into open loop mode. the secondary has nothing to do with engine operation. a smog service tech should of known that .........................new maybe?

the only purpose of the seconday o2 sensor is just for emmissions purposes

[Smoghog]

Originally Posted by superbluecivicsi

the secondary does not do anything at all. only the primary o2 sensor will send the ecu into open loop mode. the secondary has nothing to do with engine operation. a smog service tech should of known that .........................new maybe?

the only purpose of the seconday o2 sensor is just for emmissions purposes

Like I said "Your Second O2 is to check on the cat." That is cat efficiency. This has to do with different monitors running all the time and checking the cat with each drive cycle is one of them.

So the computer is thinking the cat is wasted and setting a code and going to openloop I think. I do not know what codes will bounce it out of closed loop. However running rich is hinting to me that this is the case.

And even new Smog techs have been to class. PS: 4 months of class.
However this is not the case... I've been around for awhile.

SH

[gmcuajo]

Originally Posted by Smoghog

Is it throwing a code? Probably cat efficiency. I was wrong yesterday when I told you .45v it should be .1v.

Your Second O2 is to check on the cat. After the cat there should very little or none O2. If you are just plugging it in while in the exhaust the sensor is reading alot of O2 because of no cat. This in turn is sending the computer to it's base mode(open loop) and richening is done by the computer settings not the O2.

There you have it.

SH

Those .1V is with all honda? What about 01 civic?

[Smoghog]

Originally Posted by gmcuajo

Those .1V is with all honda? What about 01 civic?

Should be the same. SH