I have a 92 CV with a 4.6 L engine. I got the car from my uncle in June and after taking care of some issues, the car got around 23/18 Hwy/City mileage. Then the Y-pipe rotted out and I got it replaced by some guys who really banged the hell out of the back of the cats while they were cleaning the flanges and installing the Y-pipe. My mileage went down by
25 to 33% almost overnight, and I wonder if they screwed up the cat when they installed the Y-pipe?
And now when I rev up the engine, I can hear what sounds like water running through a pipe (you know - like when someone flushes a toilet or is taking a shower and you hear the water running down the drain pipes in the walls) - so I wonder if what I am hearing is the loose matrix material flowing up the EGR valve?