Vroooooommmm

Ok, I’m currently driving a 2014 Legacy 2.5. All in all, I’m happy with the car.

I’ve wanted a Subaru for years, and now finally have one.

One question I have is, while driving on the highway, the car cruises beautifully going down the road at 70 to 80 MPH. When I go to pass another driver, the car gets louder when I give it gas while passing. Almost like it has an aftermarket exhaust like the kids use on their cars.

Is this normal? I was told before I bought the car, that boxer engines are a little bit noisy. If anyone has any feedback, it will be greatly appreciated.

I did take a quick look under the car today, thinking that maybe a hole in the muffler or exhaust pipe might be the culprit. Nothing looked out of place.

Exhaust noise is fairly subjective, but it is entirely possible it has been messed with. Some boy racers are known to buy the non performance versions of Subarus and try to make them in the image of the cars they really wanted but couldn't get for any number of reasons.

 

Subaru engines are a bit noisier but its usually actual engine noise you hear, ticking from injectors and so forth, it is possible someone also modified the intake and the extra intake noise is adding to the other noises. It would take a little sleuthing to figure out, mainly just getting under the car and verifying the exhaust is all stock. Pull the air filter and make sure the resonator is still attached, for the 2010 it is a white plastic bottle looking bit attached to the underside of the airbox. I am sure a 2014 owner will chime in if I am incorrect on any of this.

 

Overall the legacy is a very nice cruiser I hope you enjoy it.

The engine is not any noisier than any other modern 4 cylinder. it is the fact that the CVT is programmed to hold the engine at the HP peak during hard acceleration and it takes some getting used to as increased noise comes with it compared to the ramp up shift ramp up again noises from regular autos...

Did you buy it new, if not maybe previous owner did that Milk Jug delete performance mod. from under the air filter box.

Is this a new car to you? Is it the exhaust making noise? My factory exhaust on my '12 2.5i, '12 GT and '09 2.5i Outback is almost whisper quiet exhaust.

 

My 2012 Legacy 2.5i engine did have a boxer 'growl' to it that is not present in my 2.5i Outback or my GT. The engine is my 2.5i was EJ253 which is a different motor than your 2.5i which has a FB25. I don't know if Subaru tuned the engine for the boxer sound in the '12 2.5i. My early build GT has an insulated firewall that my late build 2.5i didn't have, this was a running change in 2012 to remove the insulation which the 2010 and 2011 have. I don't know how much that make a difference either. I quickly got used the growl that my 2.5i made, some passenger made comments to me about the motor sound.

The noise doesn’t really bother me. I just didn’t want to damage the car.

Appreciate the input from everyone.

It is new to me. Currently 133000 on the clock.

It’s been in an accident, after being repaired, I test drove it.

Got a great deal on it.

I suppose the exhaust could have also been bent when in the accident. Certain speeds and engine loads could has a noise it is contacting another part.

Just lurking around, cleaned my intake the other week I notice that milk jug thing, under the intake box would deleting it do anything. I almost took it off and just thought to myself " weight reduction right?" But I left it on wasn't sure if there was a purpose for it. Got the tekeda intake as well.

 

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Just lurking around, cleaned my intake the other week I notice that milk jug thing, under the intake box would deleting it do anything. I almost took it off and just thought to myself " weight reduction right?" But I left it on wasn't sure if there was a purpose for it. Got the tekeda intake as well.

 

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It adds intake noise, that's about it.

 

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It's likely normal, the CVT can make the engine seem pretty loud if you're not used to it. in reality its not louder than the car would be with an AT or MT thats fully loaded up but the holding of RPM and the consistent noise associated with it makes it seem louder. also passing someone that's going 75 in an under powered car you're using 100% of that cars available power so it should be quite a bit louder than when your using 20-25% around town.

Just lurking around, cleaned my intake the other week I notice that milk jug thing, under the intake box would deleting it do anything. I almost took it off and just thought to myself " weight reduction right?" But I left it on wasn't sure if there was a purpose for it. Got the tekeda intake as well.

 

Removing the milk jug affects the calibration of the air intake track and it should be tune for the change. This goes for an aftermarket intake as well.

Removing the milk jug affects the calibration of the air intake track and it should be tune for the change. This goes for an aftermarket intake as well.

 

not if you block off the opening. since it is sealed, there is no air flow through it so you're not changing the dynamics of how air is moving through the box, only how pressure waves move around the box.

not if you block off the opening. since it is sealed, there is no air flow through it so you're not changing the dynamics of how air is moving through the box, only how pressure waves move around the box.

 

I disagree that it won't affect the MAF sensor readings. The pressure waves moving around the box will affect MAF sensor that is mounted on the outlet of the air box.

not if you block off the opening. since it is sealed, there is no air flow through it so you're not changing the dynamics of how air is moving through the box, only how pressure waves move around the box.

I disagree that it won't affect the MAF sensor readings. The pressure waves moving around the box will affect MAF sensor that is mounted on the outlet of the air box.

 

In the process of getting my 3.6 tuned by xrt (Edward) hopefully he'll catch anything out of wack.

 

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I disagree that it won't affect the MAF sensor readings. The pressure waves moving around the box will affect MAF sensor that is mounted on the outlet of the air box.

 

It's possible but i highly doubt it, i did the mod, and then resealed the box and saw no changes in the things i monitor with my tune. i believe our MAFs (and most) are hot wire. so all it does is measure how much electricity it needs to keep the wire at it desired temp, and figure out the speed of flow past it. pressure does affect heat transfer but do to the fact that pressure waves are "high" pressure zones followed by "low" pressure zones i think any difference would in transfer in the high pressure zones would be negated by the following low pressure zone. also the fact the the waves are originating from the side of the sensor that has been unchanged (the engine side) would likely make any change that might be present have less of an effect on the sensor.

And there is a pesky filter there buffering airflow in the box. I mean if you can run the stock maf with a cobb cold air box/filter I am sure the ecm and MAF can handle a little variation.

And there is a pesky filter there buffering airflow in the box. I mean if you can run the stock maf with a cobb cold air box/filter I am sure the ecm and MAF can handle a little variation.

 

The waves the resonator are dampening originates from the intake valves.

The waves the resonator are dampening originates from the intake valves.

 

Inside the air filter box? Are we talking about the same resonator?

And there is a pesky filter there buffering airflow in the box. I mean if you can run the stock maf with a cobb cold air box/filter I am sure the ecm and MAF can handle a little variation.

correct, the filter buffets airflow, but pressure waves are not air flow and will be relatively unaffected by the filter

 

The waves the resonator are dampening originates from the intake valves.

correct, tho they have little to no effect on the MAF

 

 

Inside the air filter box? Are we talking about the same resonator?

yes, the resonator is in the airbox tho its on the dirty side of the filter

yes, the resonator is in the airbox tho its on the dirty side of the filter

 

I thought he might be talking about the small resonator on the pipe to the TB on N/A cars.

I am talking about the resonator in the intake box that is helmholtz resonator to dampen intake valve pulses.

 

I don't know what your tuning experience is but I started tuning about 20 years ago in the late 90's (maybe it was 2000). I have spent hundred of hours researching, reading and tuning and including take tuning class 10 years ago. While I have not tuned a Subaru, I have tuned 3 of my own cars and have a very good grasp on tuning and the theory. I have even made modification mistakes by following popular trends of modifying the air intake of MAF car, which affected the calibration and I later spent my money to undo those modifications. I am not a tuning expert. However, I have learned from tuning gurus that are industry respected and one guru in particular point emphasis was the MAF calibration. I will take my tuning experience (and mistakes) with MAF and the gurus lessons I have learned about MAF calibration over two people who posted in this thread who are seemingly mocking me with little technical expertise on this subject.

I am talking about the resonator in the intake box that is helmholtz resonator to dampen intake valve pulses.

 

I don't know what your tuning experience is but I started tuning about 20 years ago in the late 90's (maybe it was 2000). I have spent hundred of hours researching, reading and tuning and including take tuning class 10 years ago. While I have not tuned a Subaru, I have tuned 3 of my own cars and have a very good grasp on tuning and the theory. I have even made modification mistakes by following popular trends of modifying the air intake of MAF car, which affected the calibration and I later spent my money to undo those modifications. I am not a tuning expert. However, I have learned from tuning gurus that are industry respected and one guru in particular point emphasis was the MAF calibration. I will take my tuning experience (and mistakes) with MAF and the gurus lessons I have learned about MAF calibration over two people who posted in this thread who are seemingly mocking me with little technical expertise on this subject.

 

well i did study fluid mechanics, compressible and in-compressible flow. so i wouldn't say i have NO technical expertise, but if you have a reason as to why/how these minor fluctuations in pressure effect the cooling of a wire than i would love to hear it.

oh geez... i left out heat transfer.

oh geez... i left out heat transfer.

 

When I have more time, I will respond the other post. Every MAF sensor I have seen has a temperature sensor integrate into them to compensate for different intake temperatures. (it seem like the sensor use a thermal-couple to me)