Hello Everyone.

So I bought a Prelude 99 SH back in October with DC headers, and CAT already installed on it. Also, It had an AEM Cold Air-intake pre-installed on it. When I first bought it, the previous owner was running the engine a little low on oil, but from the moment I bought it, I took care of it as if it was my baby. I changed the timing belt and all what goes with it at a professional shop, I cleaned the EGR Valve and cleaned the ports, and changed the spark plugs, and all was done professionally.

Now I have been driving the car daily and its performance is just amazing, but recently I noticed that I have been making too many trips to the gas station, so I started watching the MPG. I always top it up with premium shell fuel, but it has been giving me a super $hitty MPG, the best I got was 190 miles for a full tank, which translates to 190/13= 14.6MPG. I was shocked, I mean the car is rated at 20MPG for City, and mine is mechanically sound. If I was getting 18 or even 17, I wouldn't be complaining, but 14 is pretty bad.

Did anyone run into this problem before?
Does anyone know what could the problem be?

Its been pretty expensive to drive it around. I know that the engine is running a little rich because the muffler end always has this thick black coat on it. I also should mention, that the resonator was removed and replaced by a straight pipe.

Does anyone have any idea what could the problem be??

I would really appreciate any advice/idea/help or even a bump

Thank you

 

i think maybe the straight pipe is what killed your MPG. i have a 00 ek coupe ex too and i had a straight pipe set up like yours with I/H/E and my gas mileage sucked(not like 14mpg or anything) but much lower than usual, i than swaped with a friend and got a full cat back DC sport exhaust system and it seems to do much better now, i dont know, just my thoughts.... hope it helps...

 

^ Never listen to a Civic owner, especially one with green wheels. The straight pipe has nothing to do with it.

Read both MPG threads in the FAQ. Follow all of their suggestions including the proper way to calculate MPG. If you still have questions after that, feel free to post again.