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Steve @ BMS/Fuel-It! Steve @ BMS/Fuel-It! is offline
Posts: 21,116
Join Date: Oct 2012
Car: 135i
Default 07-19-2021, 10:55 AM clear a couple things up...
First off the JB4 doesn't pass anything on to the ECU in regards to timing or AFR's.
Second, when you let off the throttle, the engine becomes a huge air pump, so AFR's will go lean and vary because no fuel is being injected. You'll usually see them cap out at 25 and it's normal so you can disregard it.

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