Quote:
Originally Posted by Stingr69
My 2010 did the "afterfiring" thing when factory new but I later had my ECM re-flashed at the dealer and the updated GM tune made the crackling on decell go away.
You are hearing the results of a lean misfire. Snap the throttle closed say while going down hill and you get very high vacuum. That high vaccum causes extra airflow to get past the throttle blades but no extra fuel. Not enough fuel is being added by the injectors for the amount of airflow so the mixture is too lean to burn properly. The partly burnt mixture gets into the exhaust and then ignites or explodes, causing the crackle and pop sounds you hear. A little is OK but a lot will damage stuff.
-Mark.
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if you dont mind me asking, why was your ECM re-flashed?
was it due to the pop/crackle or another problem and just had an additional side effect?