So I went to install my QTP downpipe today and realized I screwed up. I welded on a wideband 02 bung the same place I did on my factory DP as I knew the location was perfect for how I had run my LM-1 controller. However, just before I went to slap it on I realized that while the cutout is closed the 02 will read correctly. However, when I have the cutout open the exhaust will exit before hitting my 02. So now my question is will there be enough flow through the stock catback exhaust section when the cutout is open to still read my wideband or do I have to move it? If I have to move it, where to? There really doesn't seem to be a good place other than right before the cat where it is presently. Any input would be appreciated, especially if it's from someone with a QTP downpipe with cutout and running a wideband.

Also, since I bought the QTP DP used I'm not sure if I'm supposed to use the factory 02 housing bolts as the springs don't totally clear the DP and I'm not sure if they'll go past the flange to bottom out or not. And for some reason the DP seems to be 3/8" shorter than my factory DP; has anyone else noticed this?

 

If exhaust is venting before the sensor it will mess up the readings. When I installed my o2 dump housing I accidentally used a non-twin scroll gasket which made exhaust leak out the dump at idle, and the Afr gauge went nuts.

 

I had this same problem with the QTP. I'll see if I can find where I posted it.

BTW, I relocated it before the split. You have to have slightly lower that a 90* angle. If you need a pic I'll see if I can get one.

 

Here you go: https://www.evolutionm.net/forums/10120484-post5.html

 

Thanks for the info, guys. I figured the location would screw the readings so I didn't bother installing it other than making sure fitment was correct. Looks like it's time to make another bung and relocate it. At least now I know I'll be installing the DP and fuel pump next weekend.

Any ideas on the 02 housing bolts and the overall length questions?