anasazi

car has 60k miles, 1999 camaro SS.

recently on a trip to north carolina the best gas milage i could get is roughly 21mpg with the a/c on and cruise on 80mph

city driving is roughly 17mpg


i can sometimes hear popping out of the exhaust with the cutout open and i let off the gas. the car still has cats on it.


i've also noticed it smells of fuel sometimes when the car is parked and running and it sometimes misses on light acceleration from like a stoplighit.

what should i be checking?

Grimes

iTrader: (3)

If you have not done any mods that would require a tune, i'd say you are due for some new front 02 sensors.

jmm98LS1

iTrader: (28)

I wish I could get that good of gas mileage!! Try 14-15 city and 17-18 highway....@$2.79/gallon

blkZ28spt

I wish I got 14-15 mpg in town. I do get at least 22 on the highway, as if that's something to brag about.....


Sounds like the O2's. Do some searches on them and see what you think.

LoudmouthLT1

iTrader: (2)

Don't just replace the O2s, you need to get a scan tool and moniter them to see the voltage. 90% of your gas mileage is judged by your foot.

obZidian

iTrader: (2)

Exactly, i wouldnt automatically replace parts. A scan tool will give you a good indication of whether or not your o2'z are off. A good tune-up will go a long way in improving mileage. Plugs, wires, clean filter(s), trans and engine oils, and not to mention the right kind of coolant or mix will all help.

Also, since its been really hot down here in florida, your temps will also dictate your mileage. A cooler running engine will have cooler, denser air, and less evaporation of fuel, thus producing a more efficient burn...aka better mileage.

But most importantly, the lead on the right foot has to be eliminated!!! I dont know wat kind of gearbox your got (auto or M6) but with my 408, 3600stall, engine running at high temps all day long (200* plus), i get about 14-15, sometimes 16mpg in the city. On the highway its over 20mpg, but not sure exactly. BEsides my drive manners, i have tuned my shift points to come early, therefore i keep my rpms below 2k all day long in the city. Only when i start getting restless and hit the go pedal more is whn i see the gas go down!!

Oh, keep in mind that my tune isnt 100% and that im running rich, my trims need work and im dont it at a snails pace.

just try to tune her up and adjust your driving manners.....you get used to it. Funny, sometimes i get so upset at the mileage thing but then i remember that im the one that bought the 408, so i have to laugh at my own stupidity.

I think the worst part of all is that the gas price is going to be 3 bucks soon!!!! THAT SUCKS!!!!!!!!!!!!!!!!!!!!!!!!!!!!! (Im restricted to 93 octane due to the high compression..)

blkZ28spt

If you are like a lot of us and don't have a scan tool, just go to autozone as previously mentioned. Go to autozone, get the code pulled and see what it is. Combining the code you pull with what you find searching you should be able to tell with relative accuracy whether or not it is the O2's.

Edit: Sorry, I got threads confused. Thought you were the guy with an engine light that was coming and going.

anasazi

its not throwing any codes as far as i know

the car is stock other than a lid and a cutout, and the cutout was closed for the NC trip.

whats the best way to determine if the front O2 sensors are going bad? i do have access to an HP Tuners scanner.

loreak

buddy of mine was getting really bad gas mileage at like 50k miles and i told him to change his plugs and now hes back to the gas mileage he used to get when the car was new

plugs/filter/o2 sensors are primarily what will hurt ur gas mileage....other then ur foot of course