How far would a wideband need to be from the end of an exhaust to prevent reversion?

I know dyno widebands go at the end of the muffler and seem to be ok. Does this mean, that you could mount a wideband next to a turndown and still tune properly?

I have a jumpy AFR and am wondering if the sensor might be reading air from reversion between pulses.

 

The downside to putting a wideband far downstream is response time, especially for closed loop operations. For boost tuning, it is not a problem. Also dyno widebands (at exhaust exit) often do not receive enough gas at idle and very low load to properly tune fuel in those areas.

What wideband controller are you using?

 

well its not far downstream, as the turndowns are like 18" from the turbos.

Using my AEM wideband, it wouldnt idle for poop using closed loop correction. It just hunts for AFR and rpm. As soon as we went to open loop idle, it stabilized