still cant figure it out

Im still trying to find out what the fireworks smell is when i accelerate when Im already going over 55mph it only happens when the petal is to the metal someone once told me what it was and now i cant remember its a 1999 olds alero 4cyl please give me replies with what you think it may be

normal catalytic convertor smell?

It might very well be the type of material in the brake pads that you're using...some of them give off a type of burning smell (fireworks in your case)...hope you find the source