you said your car smells like fumes, what kinda of fumes? rotten egg-ish? that would be pointing towards a clogged cat. whats it smell like?

 

Yeah, new fuel filter is pretty cheap and a good idea. Clean the Throttle Body with SeaFoam Deep Creep. And use SeaFoam to clean the entire fuel system. Should help ya a lil bit, plus, its pretty cheap, so your not spending a ton to get a little.

 

im getting horrible gas mileage as well, but the car feels fine really pulling all the way through the rpm's and stuff, I beat an LS1 the other day. Does a fuel filter hurt gas mileage? if its getting gunked up? Ima scan my o2's tomorrow. I don't really understand crap. plugs have like 4k on them, no cat, wires are supposed to be within the last 15k miles. LIke I said, I don't see a drop in performance. So my only thing really is fuel filter or o2's that I can think of. I do have 143k miles ont he bottom end, but this **** just started happening.

 

Sea Foam you engine through the brake booster line. I'll bet anything it's the carbon build up. This will help to burn off the excess carbon. How many miles on heads? Maybe hte vlaves arent sealing all the way.

 

The heads have 10k miles or so on them, my gas mileage start went down hill from 17mpg to 11mph out of nowhere so I don't think its a problem with the heads or anything. I guess I will do some reading on seafoam.

 

i get about 275-285 per tank. high 17's per gl.

 

This is a common problem with the LT1's.
I don't think it's caused by any kind of "real" mechanical trouble. It appears to be a combination of tune up and tuning.
My 97 was at 13+ mpg or ~150m/tank. After a partial tune up, it's up to 175m/tank. I still have the fuel filter and O2's to do.
Because these engine run hot, the PCM is set to run rich. Getting the fuel curves set would probably do the most good.

 

You never said what kind of fumes you're smelling. If it's gas fumes you're either running rich or (gulp) leaking gas! I don't think you can tell the condition of the O2's by staring at them oscillating. That sounds a bit silly to me, no offence... I do plenty of silly stuff.

On the other hand, if they stay up around 800 that indicates a rich position and would mean they are ok.... I believe. If they were bad, they, for example, would read low while the car was running rich.

 

I have teh same problem..I live in Queens too..Change your o2 sensors!! I know that smell that you have.. Too much fuel!!! I am changing my 02 senrors next week...
Sebastian
ps. Now I get 140miles from teh tank, thats like 9MPG hehe in teh city...On my recent trip to NC I reached 25mpg (90mph in 6th gear)

 

thanksalot everyone, I guess it sounds like I will be changing my o2's first cause they sound to be the problem, plus it can't hurt, and I' ll change my fuel filter too. the smell is very strong, like a rich smell..
scyzoryk where in queens you live

 

Ozone Park, near Woodhaven and atlantic avenue
Sebastian
ps. And u??

 

If you want better gas mileage buy a Honda.

 

Agreed

 

... or a stock 6spd, which will give you upwards of 30mpg on the highway if properly cared for. Even a Honda is lucky to get that.

How sad and pathetic those vehicles. If every manufacturer could squeeze anywhere near the efficiency of an LT1 out of their vehicles, the gas crisis wouldn't even exist today.

 

Ya NYC traffic blows the big one and hes in queens too if you live by the BQE i feel your pain. But do what Terran2k suggested a little tune up wouldnt hurt. You can also throw in some of that Techron Injector cleaner I used it on my Lumina and noticed some better milage on it.