Small exhaust leak wouldn't impact mpg, correct? It'd have to be a large one to impact? Kinda curious. My mpg has ticked upwards, more than I'd expect, and I suspect I have a bum flexpipe--I have to turn off the fan when stopped at lights. But the car runs and drives normally, so I'm thinking the mpg is a fluke.
Exhaust leak and mpg
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Correlation is not always causality...
That said, an exhaust leak might increase MPG, and it might decrease it. Depends on where the leak is, how much scavenging was taking place, how much back pressure the system makes, and the design objectives of the system in question.
That said, an exhaust leak might increase MPG, and it might decrease it. Depends on where the leak is, how much scavenging was taking place, how much back pressure the system makes, and the design objectives of the system in question.
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If it is before the upstream O2 sensor it can definitely negatively affect fuel mileage.
I know the flexpipe is pretty ratty, but I don't have noise yet. I just turn off the fan when stopped. Which I had to do when I had massive oil leaks, but I figured that would have burned off by now.
Have to wait another day / 100 miles before I can check mpg again.
Have to wait another day / 100 miles before I can check mpg again.
I suggest your MPG increase has everything to do with the weather getting warmer. Also, the mandated date to switch from winter blend to summer blend fuel is May 1st. YMMV
I jumped almost .3 MPG in the past month. Somethin happened at Sunoco and Exxon, so I jumed over to B&H "low" detergent gas - runs pretty good, and it smells good too
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I bumped from 33mpg to 35mpg on the last tank. I got 33 from Oct thro Nov, then started driving hard and got 27-28 through Dec. I then let off and got 30mpg through the winter. Was getting 33mpg on the clock for the last month or two. Then the last tank was 35? Could be a fluke. But EPA rates this car at 28 so getting 35mpg is a sign that something is amiss. 30mpg I could see, I drive conservatively so beating EPA highway is expected. But 25% better? Maybe this tank will be 31 and I can safely ignore. [The 35mpg tank was like 550miles on the tank.]
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If the exhaust leak is letting exhaust hit the reference side of the O2 sensors, it can really throw the A/F ratio out the window.
Yup, exhaust leaks ahead of any O2 sensor is bad news, the A/F ratio goes outside the ideal range and can affect the Cat converter(s)service life.
All other downstream O2 sensor data is effected and can trigger multiple OBDII fault codes.
All other downstream O2 sensor data is effected and can trigger multiple OBDII fault codes.
Your camry exhaust leak doesn't matter for the o2 sensors. The important one's above it and the downstream's just a cat-narc for your year. But with less backpressure you have less EGR which could drag things down a little. I'd fix it, not for the mileage, but for the "hey-my-car-sounds-good-again" aspect.
Nick1994
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They get really good mileage on the highway. How fast do you drive on the highway? I've gotten up to 37 mpg in my 97 and 00 Camrys, around 65 mph. I can't explain why they get such good gas mileage either.
Originally Posted By: supton
I have to turn off the fan when stopped at lights.
Forget MPG. You're playing with fire.
Carbon monoxide poisoning is insidious and deadly.
I have to turn off the fan when stopped at lights.
Forget MPG. You're playing with fire.
Carbon monoxide poisoning is insidious and deadly.
Pipe finally gave up last week. Started it up and immediately noticed the noise. I let a shop repair the pipe, I can't weld, although it looks like they may have stitched and then covered in cement. I did ask the shop to break loose the sensor for me, which they said they did.
It tripped a code once for the rear O2 sensor, a few weeks ago; I reset that. Has been out, and is still out. But it is still reading 0V on the rear sensor, even after replacement of the flexpipe. New O2 sensor to follow (pricey!).
It tripped a code once for the rear O2 sensor, a few weeks ago; I reset that. Has been out, and is still out. But it is still reading 0V on the rear sensor, even after replacement of the flexpipe. New O2 sensor to follow (pricey!).
Nick1994
$100 site donor 2024
At first I thought they just put some stitches on, to hold it in place; but the brown metal indicates that they ran a bead. I have to wonder though if they were able to weld over the top of the pipe; am guessing either way they didn't want to blow through the old metal. Thus it's likely got voids--weld fast but don't make holes. Then count on cement to plug any leaks.
Looks like something I'd do, but at $145 of labor it does look a bit uncouth.
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