My exhaust setup is as follows. (LT1) Kook long tubes, with a catted ypipe into a Borla Exhaust. The manual says mount the sensor before the cats, but I cant, otherwise I would need two sensors. Should I just mount it on the I pipe after the cats? Do the cats really skew the mixture up that much? Thanks Guys!

 

You can't put an O2 sensor after the cats, and expect to measure the engine's A/F ratio. The whole purpose of the cats is to breakdown the NOx into nitrogen and oxygen, then use the oxygen to combine with the unburned HC and the CO, to eliminate all three pollutants. That alters the oxygen percentage in the exhaust gasses, and its the O2 percentage that the sensor reads.

I assume you are using your stock narrowband sensors for control, and just want to add the wideband (LM-1?) to allow you to tune, and keep an eye on A/F mixture. For tuning, you can just pull one stock O2 sensor at a time, and tuen with the LM-1 wideband in its place. If, on the other hand, you want to constantly monitor using the wideband, you need to put an extra bung on at least one of the header collectors, and possibly on both collectors, to allow you to switch the sensor and check both sides of the engine. Alternatively, get an extra sensor, and switch them.... althoug switching 5 wires isn't going to be that easy. Maybe Innovate has a solution.

But it isn't unusual to monitor only one side of the engine when tuning with a wideband. Its pretty "normal".

 

Hello Fred. Thanks for Chiming in. The reason I ask this question, is because down here, every tuner I know tunes with the wideband o2 sensor in your exhaust tip. Now, if the wideband were to be skewed so much be taking a after the cat reading, why are tuners doing this? I guess what I am going to do is, put the bung on only one side (probably bank 1) and just monitor one side, and tune from there. But that is why I was confused..