Recently looked at a car and it had a very dirty air filter. When changing the filter we saw a dead fly and straws where it should have been no dust or dirt at all i.e. after the filter.
As soon as we changed the filter the car performance instantly improved probably because there was a low air intake before(due to dirt) but now a lot of air was going in.
a) how did this fly and straw pieces get through. While the filter front was dirty we didn't see any holes, so how would a dead fly and these straw pieces get through the filter?
b) I'd imagine quite a bit of dirt has been going through, so it makes me wonder how does one know whether the amount of dirt that has gone through has damaged the engine to the extent that it is effecting engine performance? Is there a way to measure this?