I just did this over the weekend, with a 100k stereo potentiometer mounted in the dash. All the way left (low-volume...) is essentially stock, and about 1/3 of the range gets me as lean as I want to go for now.
Next up is a heated O2 sensor, I noticed my car going into closed-loop mode very quickly, but the idle was bouncing all over the place.
I really like having more control over the warmup enrichment!
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