Bad MPG's With X-pipe????

kylebgt · Mar 30, 2008

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????

CobraRed_96_GT · Mar 30, 2008

is it an o/r pipe? check your 02's or MIL's. I put the Mils on the before-cats on WhyAsk's car instead of aft cat like an idiot and he got horrible gas milage

streethorse · Mar 30, 2008

You should be getting better milage, I got about 1 or 2 more mpg.

joshjwc9 · Mar 30, 2008

streethorse said:
You should be getting better milage, I got about 1 or 2 more mpg.

Same here, I used to get 15.5 to 17 city now I get 17.5 at a minimum city and about 25 pure highway...

gtss · Mar 30, 2008

if the check engine light is on, deal with that first, because when its on the computer is not controlling properly
gtss

blubullett · Mar 30, 2008

When i get a new part im always on it a little bit more till im used to it.

mrvax · Mar 30, 2008

The X pipe may actually help mpg a little over stock. You need to find out what the check engine light is on for and correct it. Then consider a tune.

GA_StangGT · Mar 30, 2008

Could be a problem with your up stream O2 senors. You can MIL or turn off the rear O2 sensors with tunner, but the ones nearest the engine affect how lean/rich your car runs.

ran260gt · Mar 31, 2008

I seem to be having the same problem , I installed my O/R Prochamber last week and Im getting really crappy MPG !

I dont have a tuner yet , so I unhooked the rear O2 and plugged up the holes with bolts !

What seems to be the problem ?

Mossberg · Mar 31, 2008

I don't know what's wrong with your cars, but I gained mileage after my offroad pipe.

salstang · Mar 31, 2008

Check out why the check engine light is on. That is probably the cause of the poor gas mileage. When I put a magnaflow X pipe on my car along with steeda cat back my gas mileage was up atleast 1mpg on avg and if all highway I was gettin 2 mpg better, as long as I didn't stomp on it to hear the exhaust lol.

04GreyGtUSAF · Mar 31, 2008

I also just installed an mac o/r h pipe connected to flwmstr exhaust and am getting really bad gas mileage. I do not have mil elims or a tuner yet.

Dave0803 · Apr 1, 2008

I have an O/R X-pipe on my 03' GT and I am getting 25 around town and 28 on the highway.

topless98gt · Apr 1, 2008

I get crappy gas mileage, too, with my exhaust and gears setup. I used to get 27.7mpg on the highway, but now only about 21mpg. My car runs really really rich, or at least it did when I got it dyno'd. I've been meaning to get a tune, but I'd much rather get my intake parts first.

I've just learned to deal with it. Gas isn't really all that expensive in TX right now. Yes, it's more expensive than it used to be, but consider this: In Toronto, gas is approximately $4.25 USD per gallon. At $3.29 per gallon, that's nearly a 30% increase.

My point exactly.

R.J. · Apr 3, 2008

+1 fix the check engine light then get a custom tune.

Mossberg · Apr 4, 2008

I got 26-27 MPG doing 80 MPH on I-75 through the mountains in Tennessee and Kentucky a while back.

I have 4.10s as well. I'd get a tune if I were you guys.

I make decent hp and get great mileage with my MPH tune.

naughtygirl98 · Apr 4, 2008

I put shorty headers on, changed my H-pipe to an X, put super flow 40's on and changed my gears to 4:10's, my mpg went way down and my check engine light came on too. I took my car and did a dyno, it was running rich. He gave me three differant tunes and the only tune the check engine light does not come on now is when I have it set on my racing tune, more fuel, less air, which my car runs REALLY GOOOD on that tune, but she sucks gas bad! If I set it for more air and less fuel it runs like a 6 cyl. but it is good on gas.

Mossberg · Apr 4, 2008

Your check eng light should not be coming on if your car is tuned correctly. You may have a problem with something in your setup.

Have you pulled the check eng codes?

justinschmidt1 · Apr 5, 2008

02's sensing lean and throwing a bunch of fuel in there maybe?\\

who knows

I get bad gas mileage too...like 17 average with mostly highway ive got o/r h 3.73s other crap

billfisher · Apr 6, 2008

secondary O2's are for emiisions OBDII. the computer doesn't adjust anything for them. it simply gives CEL. your x pipe can cause the mixture to outrange your primary O2's and cause the pcm to hunt. remember stock o2's are not wide band, you can get outside of their parameter range. a tune will fix it and turn off the secondary o2's.

Bad MPG's With X-pipe????

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