recently i have noticed that the gas mileage of my hatch has droped a fair bit, and also my exhaust tip gets a black build up on the lip (i wipe it off drive to school and back and its covered in it again) i dont know if thats normal or not and if these two are realated, i checked the oil and its good. so yeah anyone please give me some insight on why A) my gas mileage went down or B) why i have that black deposit on my tip....thanks

 

have you done a tune up recently? sparks, cap & rotor?
check your tire inflation

try adding the chevron fuel system cleaner, raise my mpg by 2 mpg.

im guessing your running rich since you have deposit in your exhaust. im not a mechanic so dont trust me fully on this, but theirs a little screw which you can turn to adjust it.

 

When I bought my rex, it didn't have a cat, and I was having the exact same problem. I would actually see soot spots on my garage floor from starting the car! I put a cat on there, and didn't see too much buildup anymore. Then I swapped the engine and haven't seen a bit o crap building up in there.
I'd check or replace the cat, and then check your timing. If your timing is okay, then u may need new spark plugs, wires, distributor rotor, cap, fuel filter, possibly a new evap canister, and for good measure, have your fuel injectors cleaned. That might sound expensive, but for all that stuff(except the cat and injector cleaning) your total will be around $70-100. Not too bad to bring up the fuel economy.

 

That has nothing to do with the catalytic converter, that's a totally crapped out engine.

 

hey thanks for your input, but i have already changed plugs wires, dist.cap rotor (all from honda) and as for the timing im not sure if thats what it would be, because my car runs fine and for the most part idles at apprx. 500rpm (if this isnt normal please tell me, cuz its run like that since i bought it) o and for the cat i passed etest so i dont think its that...could i be loosing compression or something...i really dont know

 

That's what I figured.

 

B16's are suppsoed to idle around 750 +-50.

 

I was gonna say, my crx idles around 700+/- 100rpms. 500 is a bit too low of an idle.

 

hey thanx for the advice. firstly i was wrong it idles at about 600 or so, so from what one of you said that should be about right, and the chevron stuff worked a bit (car runs a bit more smoothly) and i think im gonna try that screw thing on my day off, again thanx, and if anyone can think of anything else that would be appreciated

 

could be the O2 sensor or fuel filter, I have the same prob with my 90 civic sdn.