Removed intake silencer. Fuel consumption increase?

Hi. 2.5i non-turbo owner here... Australia model.

 

I recently performed my first "mod"... hehe... the intake silencer removal.

 

First of all, piss easy mod. Took me about 20 mins from hood open to hood close. Followed the instructions in one of the threads here on LGT.com. The instructions were for a USDM LGT, but I found everything (intake-wise) to be identical on my car.

 

Anyways... a few questions in regards to things I've noticed after the mod:

 

1. Fuel consumption seems to have increased. I'd have thought that consumption should decrease since you're effectively drawing more air in, hence a leaner mixture. Not quite sure why this is happening. Any ideas?

 

2. RPMs will drop to idle much quicker than before, when pressure is taken off the accelerator. In addition, its harder to get the clutch engagement point correct, because the idle speed seems to dip low quite quickly.

 

3. Idle speed is now at 500

 

4. Engine will idle with more pronounced vibration

 

#4 is a symptom I've noticed in general quite frequently in the 6 month's I've owned the car. With the silencer mod, it seems more pronounced.

 

I don't hear any difference in intake sound at idle. Only at hard acceleration around 4000 rpm, do I hear more "growl".

 

No CEL's whatsoever

 

Any ideas on the above points?

only thing i got is for #1, since air is being sucked in quicker and there's more of it, the computer is trying to keep it's AFR at a constant and pushes in more fuel to meet the added air

How is air being sucked in 'quicker'? Unless the car is boosting more, the amount of air being consumed is as it was prior to pulling the silencer.

It sounds like something is off with the MAF sensor. Did you do anything else in there? Aftermarket filter?

How is air being sucked in 'quicker'? Unless the car is boosting more, the amount of air being consumed is as it was prior to pulling the silencer.

 

it was just an idea.... i figured if you didn't plug the whole there's a chance of air being drawn in from the open hole....

It sounds like something is off with the MAF sensor. Did you do anything else in there? Aftermarket filter?

 

Nope... the car's bone stock. Stock air filter.

 

I basically disconnected the battery negative before starting the mod. During the mod, I unplugged the MAF connector. I reconnected it after the mod was complete.

 

 

 

BTW... I'm not boosting (in reference to the post that says I might be boosting more). Got no turbo to boost with

Is it time for a new air filter????

Check the MAF is properly plugged in & undamaged.

And try disconnecting the battery for 30 minutes again.

But yes, theoretically, I'd expect a slight improvement in mpg since the engine does not have to work so hard just sucking air in.

OTOH, perhaps there's a resonance issue confusing the MAF.

 

I did this on our 2.51, but noticed more growl at lower RPM, and perhaps a bit more low-end torque (contrary to my expectations). The Primary Driver didn't like the sound, so the mod did not stay in place long enough to evaluate MPG.