Hey guys I want to run open down pipe for awhile while I fab up a part for my exhaust. My wideband O2 sensor sits 4.5" from the end of my dp will this cause issues? Or is it to close to the end of the dp?

 

It will work at WOT past about 3000 rpms, it'll be worthless at idle and part throttle till around 4000 rpms probably

 

Not to thread jack, but:

My downpipe is incomplete (only a little over 1 foot in length, needs to be welded into the flex section/rest of exhaust) and therefore also has no way of having an O2 sensor connected or even particularly close to it right now.

Even if I get a basemap from my tuner, I'm wondering if it'd still be a bad idea to start the car to check for leaks and such without any O2 sensor. Am I right or is it not as big of a deal as I think?