Rough idle, resonator delete, and fuel consumption

[Libertad]

Hi guys.

My car's about 6 months old. Ever since I've had it, I've noticed that the engine will vibrate significantly when idling. You can feel the vibrations quite clearly if you hold the gear knob, as it all transmits through.

Not sure if this matter can be classed as "rough idle" or not. Could be that this is how a boxer engine is... not sure... my first boxer. In any case, wanted to know what the general opinion is. Is the 2.5i normally this "shaky"?

Secondly, I removed the intake resonator about 1.5 months ago. Since then, my fuel consumption has increased by a significant amount. I used to be able to go for more than 550kms (probably closer to 600) from completely full to bone dry. After the resonator removal, I'm lucky to get 500 out of a tank. To put things into perspective, I filled up on Saturday. Today's Wednesday and I've driven 260 kms since filling up. My fuel gauge is on the 1/2 mark. My fuel computer tells me that I have 200 kms left till I run out. So, in total I'll be doing 460 on this tank, maybe 500 if I'm lucky and have the wind blowing in the right direction .

I took off the MAF sensor and had a look at it. Looked dirty, so I used electrical contact cleaner to clean it, and put it back. I also followed someone's advice on LegacyGT.com and left the battery disconnected for 30 or 40 mins. Apparently this "reboots" or clears the CPU's memory so it can relearn the fuel mapping.

Doing this hasn't seemed to have any effect on the fuel consumption. The air filter was supposedly new back in January, but in April I decided to swap it for a brand new one anyway.

So... I'm puzzled as to what may be wrong. Still got 1200 kms to go till my next service with Denlo in Parramatta. I hope they're a good dealer to go to.

Anyways... comments welcome. Thanks in advance.

[EJ25]

i hoenstly think that you just love hearing the sound of it when the resonator is off.. i know i love it.. according to the subaru spec sheets, the manual actually saves more fuel than the auto.. but in my 2.5 auto, ive managed 800kms driving like a granny. and on normal driving consistently get 650ish..

[Libertad]

LOL! I assure you that I'm driving like a grandma these days. Honest

Seriously, I'm not being heavyfooted or anything. And I try to use cruise control as much as possible on the motorways.

i hoenstly think that you just love hearing the sound of it when the resonator is off.. i know i love it.. according to the subaru spec sheets, the manual actually saves more fuel than the auto.. but in my 2.5 auto, ive managed 800kms driving like a granny. and on normal driving consistently get 650ish..

[Libertad]

Actually, there's no difference in sound. What I have noticed, however, that my top-end pickup is far better than it was before (it seems at the expense of increased fuel consumption).

Seems like a true mystery for Denlo to uncover.

[EJ25]

denlo wont be able to notice a missing resonator unless they take out the whole box out..

[overl0ad]

same in my car since day1.

now don't feel it due to cat back and pitch mount

[[Liberty2.5]]

hmm my liberty has quite a rough idle whilst sitting at the lights... wondering what it is