Exhaust smell

[brandnew161]

I've been having some recent trouble with bad gas mileage. I've done ALL regular maintenance to try and solve it. I'm not getting that bad mileage but 55miles on 3 gallons isnt too hot either. Since i've done all the little stuff i'm now looking at my major mods...catback and cams/gears. I've been playing around with the timing every few weeks to try and notice a difference in mileage but nothin. Messin mith the timing as fixed a high idle though. I dont know if my car is running rich but i can smell unburnt fuel in the exhaust. Its smells like you've been running a chainsaw for an hour and u can still smell ure clothes for the rest of the day. So its pretty noticeable. But maybe the car isnt running rich and its just the catback. I have a race header and there really is no cat on the car...just a test pipe really. When installing a catback do you smell gas more noticeably than with the stock pipe?

[nov173]

could be a bad 02 sensor... you getting any codes? could be your primary sensor

[c03morrison]

i would also like to know because i am getting that same smell

[KS1]

it's just because you eliminated your cat

the cat normally burns up most of the unused fuel and other undesireables coming from the engine

I have a race header, and I get the same smell

don't worry about it, but plant a tree or two to offset the damage to the environment

[KS1]

and you probably smell it more now than with the stock exhaust because it flows better and doesn't have to snake through the muffler and lunchbox

[FuriousFocus]

I have a small catco cat on the car with my setup and you can smell the fumes alot more now. No worries. With the bad gas mileage, if you just recently installed everything and your bank1 sensor is pretty new (like 50 -75,000miles) then you are proably fine. But I would replace it with an NTK sensor (not Bosch) I don't like there sensors, and you may notice an improvement.

I know I tore it up a little when I first put the header on, my gas mileage was down for awhile.

[KS1]

yeah, as far as the mileage, it takes the ECU a little while to readjust to all the new goodies you just installed

[brandnew161]

the cams and catback were installed in late july... so theyve been on for a while.
I have no codes, but i did hook up an O2 cheater due to the race header.
I have 53k on my zetec and i'm going to get new o2 sensors soon. I've heard good things about NTK

Another question...when reseting the ecu so that it can relearn the air/fuel map, why do you have to let the car idle afterwards for 5 minutes? If it takes 150 miles for the computer to fully establish the fuel map then isnt the whole idle process a waste?

[KS1]

oh, ok, I thought you had just put them on

this sounds dumb, but check your tire pressure, the focus is kinda picky about tire pressure, it can screw with you mpg

[brandnew161]

tire pressure is good, 43 psi in all 4.

does cam timing really have an effect on gas mileage? I only have stg 1 compcams so i'm not running any aggressive grinds. I havent been to the dyno yet to have my gears adjusted, i want to wait until the summer when i can install the turbo. Right now my gears are set zero and zero and i know every motor is different...but would any change from zero either way (no more than +or-2 degrees) really affect my gas mileage this much?