kylebgt

Ok long story short I was getting 24mph before the swap and now I get 19, while shifting at the same rpm's same roads[:@] I can't afford this with the gas the way it is. Do x-pipes usually lower your mpg's? I have a check engine light so will that maybe make it run really rich? I just can't understand where all this gas is going????

Hoppers04Gt

You may need a tune

5speed01GT

well first off you should probably at least get an mil to get rid of your check engine light

cliffyk

If one (or both) of the front O2 sensors were damaged during the X-pipe installation it would cause the engine to run rich--what codes are being thrown?

02TorchRedGT

Yep, I would do the same or get a tuner to turn the back 02's off. This is probably your fuel problem. From what i understand...the rear sensors send signals to the Computer to determine air/fuel mixture. I'm not 100% sure of this...but makes sense to me.

cliffyk

The rear sensors have nothing to do with the AFR, they are 100% dedicated to monitoring the efficiency of the catalytic converters/[/align][/align] [/align][/align]MIL eliminators won't hurt (make 'em yourself for $5)--howeveryou need toget the codes read to figure out why it's running rich.[/align][/align]The PCM controls the AFR to keep it within the range it has been programmed to maintain, by using the constantly switching signals from the front O2 sensors to keep the averageAFR where it should be. A voltagefrom the sensor of0.0V to 0.4V indicates lean, a voltage of0.5V to 0.9V indicates rich.[/align][/align]It should be obvious that a bad or improperly wired O2 sensor will most likely produce low or no voltage--the PCM then thinks the mix is very lean and compensates by trying to enrichen it == poor gas mileage. A cold sensor (due to heater failure/bad wiring, they have to be at least 650°F to work at all, 975°F+ is best) "looks" electronically like a very high value resistor and produces no output also making the PCM enrichen the mix.[/align][/align]Here's a link to more than you probably want to know about narrowband O2 sensors...[/align]