Exhaust leaks and fuel mileage

[Banshee1967]

Ever since I got an exhaust leak I have noticed my fuel mileage drop 15-20%. The leak is at the header at the pipe to convertor.

The O2 sensors are new.

Two of us say that the leak can drop overall fuel mileage by causing the right bank to run richer, one says no.

Am waiting on my new exhaust system. Leak has been around since a month after I replaced the O2's as I had to crank on one size to freeze up the seized sensor.

Mileage was great before the leak became noticable.

Thoughts?

[Spaz]

that leak will cause your sensor to detect a lean condition and throw more fuel in tot he engine... look at your exhaust tips... they are probably black as coal... have you thought about getting a clamp and welding it over the leak???

[sunsetorangess]

Band clamp maybe?
J

[Banshee1967]

I'll get to it when the weather breaks..Been raining and snowing off and on.

Looks like 30 minute job at most.

Thanks!

[Spaz]

Band clamp maybe?
J

one time... at band clamp...

[GatorSS]

Ditto on the leak causing a false lean condition detection resulting in extra fuel added to that bank. Ergo, your fuel mileage drop.

[sunsetorangess]

one time... at band clamp...

Lol Yatzeee

[side2000]

that leak will cause your sensor to detect a lean condition and throw more fuel in tot he engine... look at your exhaust tips... they are probably black as coal... have you thought about getting a clamp and welding it over the leak???

exhaust leaks pre-o2 sensors do just this.

[Banshee1967]

After fixing the leak, and being that the PCM has detected the lean condition and added more fuel, would it be wise to unhook the battery to reset, or allow the problem to correct itself?

Thanks..

[side2000]

it will correct itself. it's pretty sensitive that's why we have 4 o2 sensors. it instantaneously reads what it sees and adjusts fuel accordingly.