[nestyle]

Hello all,

I recently installed some custom 6-to-1 headers on my e46 m3 that removed my secondary o2 sensors (some pics attached below). In the process, I found one of my front o2 sensors to be slightly short, so I decided to replace it with one of the o2 sensors I removed from the oem headers post-cat. I drove the car around for a bit and it seemed to run well under load, but once I reached a cruising speed (~2.5-3k rpm) and sat there for a few seconds, I started getting vibration and power cut indicative of a dead misfire. I flashed my ecu with a remap from Ecuworx to remove any secondary o2 DTCs and the secondary air pump DTCs (my SAP is still on the car, just not running) and the problem still persists. Idle also misfires. I should have taken more photos during the install, but wondering if swapping my rear o2 sensor to the front connector is causing some of this issue.

Any help much appreciated, thanks!

[Jbonly21]

It looks great, did you use new OEM gasket? With the car running, get some brake cleaner and spray where the headers are mounted to the head, if there’s any changes in the idle, you found your problem.

[nestyle]

Originally Posted by Jbonly21

It looks great, did you use new OEM gasket? With the car running, get some brake cleaner and spray where the headers are mounted to the head, if there’s any changes in the idle, you found your problem.

Thank you for the help, don’t see any signs of a leak around the gaskets there. Didn’t use oem gaskets, but ones that had slightly larger diameter to fit the slightly wider primaries on these headers. Bumping this as I’m still running into the same issue. Tried switching the o2 sensor positions and the car runs slightly better at idle but starts misfiring and cutting power under load