My exhaust has been leaking progressively worse for the past 3 or so weeks. It always had a leak, but it's gotten much worse. I was procrastinating fixing it. I procrastinated one too many days because the weld from the tail pipe to the catalytic converter flange completely broke loose and my catcon was dragging on the ground. Luckily I was only 2 miles away from a very good muffler shop.
Well 66 dollars and a lot of inconvenience later it's fixed. My question is, now that my exhaust is leak free, can I expect any change in FE?
I know for sure that the biggest impact a leak would have is if it were upstream from the O2 sensor. That would cause a false reading (lean) in which case the ECU would richen the mixture unnecessarily. Otherwise I wouldn't think a small leak downstream would have much of an impact.
my rear muffler once broke off
it was basically just dangling from it's suppots and making a lot of noise so i drove for a couple of days without is.
wich made the car sound like a truck, but it also seemed to give me a bit more power...less exhaust restriction i guess, although it may partly have been a psychological effect from the noise...i don't recall any notable effects on FE.
i'd assume that as far as there's no sensors involved, the shorter the exhoust the better. so in theory a new exhaust might cause i slight drop in FE, but since old exhausts tend to get clogged with soot and rust a new muffler will usually have a little less restriction.
all in all i doubt small holes over a short period will do much for FE.... a complete removal or redesign of the exhaust system might do something
Yes, it can. The entire exhaust system is part of the power production for the vehicle. The size of the piping, where the exhaust combines between cylinders, length, all affects it. Dropping the exhaust off at the engine directly will kill power and fuel economy, because the system performs a certain amount of scavenging. What affect a leak after the cat will have I'm not sure, it would depend on the rest of the system.