exhaust leak and gasmilage???

[scttydb411]

every thing he said^^^if the exhuast leak is before the sensors. if it's towards the back it's not the issue and it's something else.

[falqon]

If somehow you have a exhaust leak before the o2 sensor, (which is pretty rare) then yeah, better get it fixed.

A hole in the exhaust after that should not be detrimental to MPG at all. Losing back pressure should cause highway MPG to go up at least in most imports. The reasoning is this, yes you might lose some torque, but you should gain HP. Back pressure helps low in the power band, but as the RPM's climb the restriction outweighs any benefits. I had a hole in my old fox body mustangs muffler for a couple months, MPG actually went up. A test pipe does not hurt MPG, I have never seen or heard that theory, and if that were true, then nobody would buy "hi-flow" cats.

Most cars that come off of the assembly line today suffer from too much backpressure, the reason is the catalytic converter. The stupid things rob you of mid-high end power and really hurt fuel economy. If the exhaust leak is after the cat, this whole thread is probably moot, that restriction will negate much of what a hole in your exhaust might do.

[1439/2000]

If somehow you have a exhaust leak before the o2 sensor, (which is pretty rare) then yeah, better get it fixed.

A hole in the exhaust after that should not be detrimental to MPG at all. Losing back pressure should cause highway MPG to go up at least in most imports. The reasoning is this, yes you might lose some torque, but you should gain HP. Back pressure helps low in the power band, but as the RPM's climb the restriction outweighs any benefits. I had a hole in my old fox body mustangs muffler for a couple months, MPG actually went up. A test pipe does not hurt MPG, I have never seen or heard that theory, and if that were true, then nobody would buy "hi-flow" cats.

Most cars that come off of the assembly line today suffer from too much backpressure, the reason is the catalytic converter. The stupid things rob you of mid-high end power and really hurt fuel economy. If the exhaust leak is after the cat, this whole thread is probably moot, that restriction will negate much of what a hole in your exhaust might do.

Not rare at all on a turbo car.