Cause of MPG Drop?

kburnell

kburnell

Member
Ok, not sure if this is the right place to post it but here we go. About 3 weeks ago I got my magnaflow catback installed...love it
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The problem is since then I've noticed a 3-7 MPG drop and was wondering why. I almost always shift around 3k so my driving hasn't changed. Do you think it could be a leak causing the issue? Any other ideas?

 
Could have got ahold of some bad gas. Start going to decent brand stations. With a catback on your car you should be ok with a tune so that's not the problem. You check for any leaks anywhere? Fluid or Gas leaks?

 
Could have got ahold of some bad gas. Start going to decent brand stations. With a catback on your car you should be ok with a tune so that's not the problem. You check for any leaks anywhere? Fluid or Gas leaks?
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I haven't noticed any fluids dripping/pooling anywhere. Not sure about gas leaks. I'm a big noob when it comes to cars
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I may just make an appt at M&A to have them check it out and see if the clamps on the CBE are loose or something.

 
Leaks in exhaust after cat like in your system generally would not cause that problem. I can't say I have seen any exhaust evevr cause that much of a drop. Unless you are on the thottle all the time. I would put my guess on bad gas. Tire inflation?

 
Leaks in exhaust after cat like in your system generally would not cause that problem. I can't say I have seen any exhaust evevr cause that much of a drop. Unless you are on the thottle all the time. I would put my guess on bad gas. Tire inflation?
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Thanks for the info. I'll fill up at Mobil or something next time and see if it helps. The biggest drop was this last fill up so it's quite possible that was the cause.

 
i have heard that is that's one of the worst places in portland to get gas and you car could be fuusy with its tune and back pressure lost from changing your exhaust

It's the Scrubadub place on Forest Ave in Portland. Same place I usually fill up.
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its a typical drop in milage..... your using a bit more right foot now. you wanna hear that sound.

 
UPDATE

Ok, looks like you guys were right about it being bad gas or something. When I was filling up at the Scrubadub place my avg mpg for the tank was 18.3. I filled up at Irving the other day and now my average is 24.9. Looks like I'll be filling up at real gas stations now LOL. Thanks for the info
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that's all i pretty much use is irving gas cause i get pretty good gas mileage and its always consistent

 
that's a huge jump!. Must be a lot of alcohol in the scrubadub gas or something nasty.

Now I have to check my mpg. I never thought it could be that much of a difference.

 
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