02 sensors with no cats

[spydr]

Question for all, I am running fabspeed headers with no cats. Would changing the o2 sensors that normally are located after the cats help with the CEL or are all 4 of the o2 sensors the same?

[Loren]

There are two sensors in front of each cat two sensors behind each cat.

The two in front are the same and the two behind are the same.

[PTEC]

I assume you are talking about a check engine light due to Cat Efficiency faults due to your lack of catalysts. If this is the case, changing the o2 sensors wont do anything for you to get rid of the check engine light. Your best bet is probably to look into an DME reflash. Among other things the reflashed DME has the ability to prevent the CEL from being illuminated due to certain faults (namely cat efficiency).

At least I assume this is such as reflashes for many other makes and models have this ability.

[berty987]

I was under the impression the DME adjusts the timing and fuelling to suit the results from the O2 sensors. The upstream sensors are the same as the 996 but the down stream units are different I beleieve. I think the only place to buy them is Porsche anyway.

Edited October 22, 2007 by berty987

[pebblemotorsports]

Question for all, I am running fabspeed headers with no cats. Would changing the o2 sensors that normally are located after the cats help with the CEL or are all 4 of the o2 sensors the same?

You might consider replacing the rear O2 sensors with simulators - basically devices that output a signal indicating that the mixture is correct and the cats are working efficiently without even sampling the exhaust. They basically spoof the computer.

[vizcarra44]

Question for all, I am running fabspeed headers with no cats. Would changing the o2 sensors that normally are located after the cats help with the CEL or are all 4 of the o2 sensors the same?

You might consider replacing the rear O2 sensors with simulators - basically devices that output a signal indicating that the mixture is correct and the cats are working efficiently without even sampling the exhaust. They basically spoof the computer.

Bingo,

Thats the trick. Just like what the bike guys do. I used to just short out the signal wire from the O2 sensor going back to the ecu. grounding out the signal the ecu will think he's got a serious lean condition and will richen up your mix to a max of 25% but of course you will not have a smooth idle and such. I guess its a trade off. on the rears you would need to lock the signals above the 650 Mv range so as to fool the Ecu. :rolleyes:

vizcarra44