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Discussion Starter #1
ok i am finally sick of filling my car up every other day to write this thread. about 5 minutes after i finished my exhaust install, O/R X and violator catback and mil elims from LMR. granted i drive it "spirited" but i did before i got the exhaust on and my gas mileage was no where near as shitty as it is now, im talking like 9-11mpg right now, AND my CEL is on!! i KNOW its the mil elims. anyone ever heard of mil elims not working? what can i do about it? and finally is it normal for mpg to drop greatly?
 

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Get a tuner. That will allow you to actualy turn em off. Go get it scanned and make sure its the rear 02's and not something else. If its something else that may be hurting your mileage as well.
 

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ok i am finally sick of filling my car up every other day to write this thread. about 5 minutes after i finished my exhaust install, O/R X and violator catback and mil elims from LMR. granted i drive it "spirited" but i did before i got the exhaust on and my gas mileage was no where near as shitty as it is now, im talking like 9-11mpg right now, AND my CEL is on!! i KNOW its the mil elims. anyone ever heard of mil elims not working? what can i do about it? and finally is it normal for mpg to drop greatly?
Well with the CEL light on it might be running pig rich. Plus you're probably getting on it all the time because of your sweet exhaust. Also mil eliminators won't work if the O2 sensors are bad.

Did you disconnect the battery for a little while after installing the MIL's? I would also check the connections and look for burnt or pinched wires. Did you only put the mils on the back O2's
 

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Discussion Starter #5
lol yeah, mils on only back 2 im not stupid, yes i let the computer reset, o2's were fine before the install, im almost positive they went in the same sides they were in. i know fronts are in the front. im really not getting on it more than i used to. i cant just tune them off, i have to pass emissions, there is a way around it with o2 sims here in stl.
 

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YOu have different problems than your exhaust sytem. Just swaping on a catback wont make your MPG go down

I would bet money its your O2 sensors are bad. When you changed the exhaust they ****ed up. You need to scan it with a scan tool to see if the sensors are bad they could be bad without tripping a light
 

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Discussion Starter #7
how would they have gotten messed up during the install, they came out of one pipe strait into the new one....i will scan it inthe morning but i dont know. i have all the correct tools including the o2 sensor socket so???
 

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It doesn't take much to mess up an 02 sensor. Sometimes just banging em around a little will do it. I haven't heard of a mpg loss like that ever from exhaust. You have something wrong. Not to mention the rear 02's don't adjust your AFR so maybe its the fronts ones.
 

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If you O2 sensors are broke the engine will run very very rich wich will adjust Air to Fuel. I have seen MPG loss that bad from O2 sensors before

And the way it works in a shop if you drop and O2 sensor just go get a new one chances are that one wont work
 

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As evryone else has said, get the exact codes and then work the problem--rampant speculation just wastes time...
 

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I wasnt saying the exhuast messed up your spark plugs. i'm saying they could be fading out or going bad, bad plugs = bad mpg. And yes, O2 sensors do affect your mpg also. I need to re wire mine because one of mines wires is hanging across the top of my exhaust, so it pretty much burnt it.
 
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