air intake sensor with oxygen sensor controls lean or rich mixture.Thats like my chip fools air intake sensor to read perfect temps,so mixture will be at perfect 14.7 to 1.
I now before my chip in cold winter below 25 degrees my mileage suffered.Now its stable on cold days as warm days.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt