Rich mixture, bad fuel consumption after 3" exhaust installation

[rvr]

Bought a Mitsubishi RVR a few months ago. Its got a 4G63TI engine w/ a fuzzy logic trans. I Recently did the ff. mods.
1. K&N air cleaner
2. Stock exhaust replaced with 3" pipes (starting from down pipe) w/ a custom made 12" long, 3" pipe straight through oval resonator
and at the end,
a Fujitsubo 3" pipe, 20" long straight through oval muffler.
3. Removed Catalytic Converter

I did notice top end power increase with the upgrade but my problem now is:
1. Fuel consumption noticeably increased.
2. I could smell from the exhaust that the mixture is, maybe either rich, or maybe there is unburnt fuel.
3. Seems low end power or torque decreased.

Though the engine runs and idles very smooth (with and without air-con).

My question is how can I restore back its fuel consumption back to normal (without returning back the stock exhaust system)?? I read somewhere in the net that after intake-exhaust mods, removing the ECU fuse for a few mins, then running the engine for another few mins (without stepping on the gas), then final restarting again the engine, would RESET the computer box and make it sense new mixture settings, and finally make new adjustments. Did this procedure several times, but there wasnt any improvement.. still smell rich mixture on exhaust and high gas consumption. Btw here's a link on the specs of my RVR
http://english.auto.vl.ru/catalog/15732/
Customized ver from Australia.. http://www.xspeed.com.au/ssport/09rvr/09rvr.htm
My RVR and its engine looks exactly like the attached fotos

Thanks in advance guys for any advice or suggestions

Btw, i'm from the Philippines.

 

[gigahz95]

what the hell

 

[sjwelna]

Did you put the grounding straps back on your new exaust? If not, i've heard that it can cause bad gas mileage as a result of messing with the o2 sensors.

-Steve

 

[Eagle_Summit]

what the hell

same here

 

[98RedGs]

Awsome, I've heard of those but never seen one yet. Truly awsome! Your probably running rich or at least smelling it now because the cat is removed. Not uncommon actually.

Could consider removing your lower honeycombs out of your maf....

www.vfaq.com

 

[Quasimondo]

That's the Expo LRV that MMC should've sent us...

 

[dsmayhem]

That thing's fricken cool!

 

[rvr]

@sjwelna
Thanks for the advice. The only wires or strapsi didnt reconnect after the exhaust upgrade was a pair of wires which connects to the cat. I gez its the cat's temperature sensor which lits an idiot light on the instument panel (pls correct me if i'm wrong). what i did was i shorted the 2 wires so that the idiot light wouldnt light since the sensor or probe was left on the cat since its screw was already rusty frozen, for sure it would break (wouldnt budge even after generous amounts of wd40).

@98RedGs
Thanks for the tip, will try and remove that lower honeycomb tomorrow

I'd just like to share with you guys that this vehicle is realy fun to drive. Very good traction and handling due to AWD trans. It is really faaast, 220 horses for a stock engine, they say its an EVO 3 engine. My nephew, who has a JDM Integra type-r vtec, 5spd manual (normally aspirated 220 hp) was surprised when were almost neck to neck on short race in our neighborhhod. I also like the long travel suspension since we have a lot of bad roads here. Its really a sleeper since nobody knows how fast it is since this is a Japan import, originally right hand drive then converted to left. The RVR didnt come out in the Philippines.
I'm now looking for surplus 5spd AWD trans so i could enjoy more the 4G63's muscle. But if there's an invecs2 w/ comp box around, that would be better. Not sure though if it would plug in my existing harness.