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cmg5461 cmg5461 is offline
Junior Member
Posts: 185
Join Date: Nov 2014
Car: 2008 E90 335xi 6MT
Default 06-23-2016, 06:20 AM

Originally Posted by Jeffman
Just to be clear, this STFT oscillation has nothing to do with the open loop OBD readiness test the DME is programmed to do during the drive cycle when cruising at ~60 mph? During this part of the drive cycle the DME oscillates rich-lean for ~10 minutes, I recall, and you can actually see the STFTs oscillate up and down.

Running rich-lean-rich-lean is a technique to increase catalyst efficiency. Running lean creates a lot of NOx and running rich heats the catalyst converting the NOx to N2 and CO2

E90 335xi 6MT - Deep Green
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