Originally Posted by osteologation
So y is it that smog pumps are so uncommon. My bronco and 1983 delta had one but the other 20 cars I've had have not. Just seems like something that isn't needed now that engines/efi are of more efficient design.
Not true - many cars have air pumps on them even now!
The big difference is that they are electric and only run for the first 20 seconds or so after startup. Back then, it used to be about reducing emissions from poor fuel control with shitty technology cats -
NOW, it is all about getting the super-efficient cats up to operating temperature as fast as possible. One car I'm do some work on gets center catalyst temperature to 700C IN 20 SECONDS
. The sooner you are hot, the quicker you reach your best catalyst efficiency.