mpg loss or gain ???????? - Jeep Commander Forums: Jeep Commander Forum
Exhaust Questions or advice about exhaust systems? This is the place...

 
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post #1 of 8 (permalink) Old 01-05-2013, 05:29 PM Thread Starter
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mpg loss or gain ????????

has anyone noticed a loss or gain in mpg after exhaust change from stock to performance muffler,mine use to show 18.6-19.2mpg at 60,taching 1600 rpm,s now the best has been about 16.3,,running 3.7 eng. 2"lift.265-70-17 tires,guess i need more back pressure, or something,also have air intake,2008 model

Last edited by oldtimer; 01-05-2013 at 05:32 PM.
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post #2 of 8 (permalink) Old 01-05-2013, 08:39 PM
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Did you change the pipe diameter? Also did you reset the ecu.
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post #3 of 8 (permalink) Old 01-06-2013, 04:50 AM Thread Starter
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exhaust is still 2.5 in. have not reset ecu.,tryed a flowmaster 50,frist time why to loud,an sounded like a kids drifter car,when with a stock shorter less b-pressure an inside is almost noise free,wife didn,t notice,this is a 2wd, 307 gear road veh. only,first jeep ever to go back on fuel mileage,after modes, go figure?????????????
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post #4 of 8 (permalink) Old 01-06-2013, 11:34 AM
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I mean unless your pushin it harder cause you like the noise but it shouldn't have dropped that much . I would reset the ecu and see how that goes.
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post #5 of 8 (permalink) Old 01-06-2013, 02:15 PM Thread Starter
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reset ecu,and reinstalled a heat sheild,will try that an see how that works
,just a cruiser,before all the changes, it would get 20.7,21.3 at 70,just didn"t think wheel"s/tires,would hurt that bad,my old cherokee4x4,3" lift,31" tires average,s a regular 19-19.3 at 73mph,figure that one out???????????

Last edited by oldtimer; 01-06-2013 at 02:22 PM.
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post #6 of 8 (permalink) Old 01-06-2013, 02:22 PM
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The lift shouldnt really make it drop like that.. Unless it interfered with the great wind resistance of the Rolling Brick.. The only mod you did that resulted in the mileage drop was the Muffler though correct? you were doing well with mileage with the lift?
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post #7 of 8 (permalink) Old 01-06-2013, 06:03 PM Thread Starter
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The lift shouldnt really make it drop like that.. Unless it interfered with the great wind resistance of the Rolling Brick.. The only mod you did that resulted in the mileage drop was the Muffler though correct? you were doing well with mileage with the lift?[/quote]

that was mileage before lift,after lift average was 18.9 at 65 and 17,9-18.3 at 70. plus you add about a 3-4 mph faster with bigger tires,an an have to add 10 miles to ever100 miles traveled,just the muffler has affected the mileage will see on next trip,muffler installed correct also.

Last edited by oldtimer; 01-09-2013 at 05:44 PM.
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post #8 of 8 (permalink) Old 01-06-2013, 08:31 PM
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Alright Yea sorry i couldnt be of more help. Let us know the updated mpg.
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