I am running an open downpipe on a d15b7 with the O2 bung placed about 12" down from the turbo, then there is about another 3-4 inches of pipe after it. I read in the Innovate LM-1 manual that exhaust leaks let air into the system which will cause the reading to be leaner than the motor actually sees. Since my O2 bung is so close to the end of the pipe could that cause why I am getting leaner than normal readings? Or should it not matter as long as there are no leaks before the O2 bung?

 

bump

 

if you're at WOT there won't be any air leaking into your exhaust from the end of the downpipe.

did you just remove your exhaust & notice it going leaner? that's normal, better richen it up.

 

Yeah the reading will be skewed if you only have 3-4" of pipe after your 02 sensor. Get some more pipe or finish your exhaust