major fuel milage drop after installing o/r x-pipe

[gotchopsticks]

i am a proud owner of an '02 GT. i installed my MustangTuning o/r x-pipe last wendsday, and everything was fine. then friday my "service engine soon" light comes on. usually, i get about 100 miles per 1/2 fill, usually about 10gallons, so 200miles on 10gallons. so far i have 60 miles for 1/2 a tank, 40 miles less than usual. i have not been driving any different than before, if anything less aggressive because of the noise factor. my question is what is going on with my fuel milage, and how do i fix it? im guessing i need MIL eliminators. any help will be appreciated

 

[GTn00b]

yes you need mil eliminators, my gas mileage still sucks even after the mil's i get about 150 miles per tank strictly city driving

 

[jbrown]

your check engine light can be fixed with the mils. for some reason my light hasnt come on yet even though i put on my o/r x pipe about a month ago. you might need a tune that could help your gas mileage.

 

[LightsandSirens]

Your gas mileage sucks now because your car is louder and meaner sounding. You are probabyl driving it and enjoying the sound so much that you're doing things that are hard on gas. For instance, downshifting up to lights, keeping it in lower gears as you crawl through traffic, keeping it in 4th as you cruise along on the highway, punching it here and there, ect.

 

[smokin'Red35th]

how would an x-pipe drop your mileage other than how you drive it?

 

[mcmmotorsports]

It doesn't, it is a "New Exhaust Sound, Right Foot Fuel Mileage Problem."

 

[back_in_black]

I think it actually does reduce your milage by reducing the low end torque. On my 03 cobra I wasn't able to regain the low end torque until I got a custom tuned chip !

 

[01MachGT]

Actually, the reason that your getting crappy gas mileage is because your car is going into safe mode because of the error code that is being thrown. When this happens the computer messes with the timing and A/F ratio in order to keep your engine safe. So it throws more fuel into the mix. The MIL eliminators should take care of the problem

 

[ChrisGT]

Actually, the reason that your getting crappy gas mileage is because your car is going into safe mode because of the error code that is being thrown. When this happens the computer messes with the timing and A/F ratio in order to keep your engine safe. So it throws more fuel into the mix. The MIL eliminators should take care of the problem

If this is true then why is it that I get exactly the same gas mileage now that I did before I installed my o/r X. Also, if I'm in limp mode why am I running faster times at the track?

 

[01MachGT]

Do you have the check engine light on?

 

[rustang04]

if i am not mistaken aren't the rear 02's just cat monitors!!!!! the front 02's control a/f ratio.

 

[jstreet0204]

The rear o2's don't effect perfomance. That isn't the problem, and it isn't going into limp mode because of the rear o2's. Only the front o2's would cause that. Any time you make a change the eec takes a while relearn things. You can speed this up by clearing the Keep Alive Memory. Just disconnect the battery hit the brake pedal a few times and leave it off for about ten minutes. Then give a day or so and see if it improves. It may also be like others have said unintentionally driving it a little harder. If it still happens get the codes read and see if there are any problems with the front o2's I had some issues with the harness extensions when I put mine on.

 

[COBRA90GT]

It doesn't, it is a "New Exhaust Sound, Right Foot Fuel Mileage Problem."

Agreed.

BTW - Get the MIL Elims to make the pesky check engine light go away.

 

[gotchopsticks]

i used a code reader device today, and i got the code 420, and 430, and the book said that it is the catalyst malfunction on the right and left side, but now my service engine light is off. like i said i am not driving any harder than before, even though the exhuast is loud. i will try the brake thing before i spend 50 bucks on the MIL's. thanks