Rep Power: 0

alright guys...i drove really hard this week
i would always rev up to 4.5k and then shift to 2nd gear

I got 250 to the tank!!!!!! WTFF!!!
STILL!!!!! around 20 mpg!!!!! How the **** do I check out the problem!?

 
Rep Power: 248

It's hard to diagnose if that's all the information you're giving us. I don't recall anyone here having that problem before, so bear with us. If you're getting terrible mileage, my first instinct would be fuel filter, but your car's too new for that to be a problem, usually, and it's a bitch to get at on these cars. I still would focus on two areas, fuel delivery and intake. Do you have the factory intake? And the car's not throwing a check engine light?

To others besides the OP: What would you think about doing an ECU relearn? It sounds like the engine's getting too much fuel. Faulty MAF sensor, or bad sensor read somewhere?

 
Rep Power: 244

4.5 driving hard? Bounce that **** off the rev limiter every shift...seriously though have you checked to see if your leaking gas?

 
Rep Power: 248

As obvious as that sounds, he's got a point. Are you sure you're not leaking any fluids?

 
Rep Power: 0

Not too much of a car expert, but I don't see any fluids actually leaking on my driveway or when i pop the hood. I think my exhaust has a small crack (near the muffler), would that affect anything?

Also, when I accelerate...I actually hear the gas being eaten up (hissing sound). Is this normal? hmm...

My mechanic didn't see any problems with it, should I have it check out again?

 
Rep Power: 0

And I have an AEM v2 intake with a brand new filter.

 
Rep Power: 812

um im pretty sure the hissing is air going into the intake lol.

 
Rep Power: 0

some people insist that an old O2 sensor will decrease mileage by about 2-3 mpg on a 60k+ car

Also installing a free-er flowing intake will always drop your mileage. More air needs more fuel to mix right, hense the mileage.