puzzling long tube question

**bmwmteam** · 05-02-2009, 02:10 PM

maybe i just don't comprehend things very well, but iv been shopping around for a while for a set of long tube headers w/ emissions and on all of then they have a hole where the tubes come together for the o2 sensors. now do they go before the cats on the stock set up. and if so couldn't you just not install the cats and the 02 sensors would never know the difference? thanks

**c5z28** · 05-02-2009, 02:18 PM

On our cars there are 4 o2 sensors. 2 before the cats to tell the car how efficiently it is burning the fuel and 2 behind the cats to see if the cats are working. So yes most people don't run cats, and yes some run o2 simulators but that's a waste of money. Running front o2's is only going to keep the car running optimal in all conditions.

**WS6ICK2K** · 05-05-2009, 09:51 AM

Originally Posted by c5z28

On our cars there are 4 o2 sensors. 2 before the cats to tell the car how efficiently it is burning the fuel and 2 behind the cats to see if the cats are working. So yes most people don't run cats, and yes some run o2 simulators but that's a waste of money. Running front o2's is only going to keep the car running optimal in all conditions.

Agree with him. Most people do away with the second ones. You can have them deleted permanently to fix the cat efficency test. Def need the first ones for fuel ratio etc...