Need Help - Magnaflow mufler and K&N Cold air intake upgrade issue with mpg - Jeep Commander Forums: Jeep Commander Forum
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post #1 of 6 (permalink) Old 07-25-2007, 09:10 AM Thread Starter
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Question Need Help - Magnaflow mufler and K&N Cold air intake upgrade issue with mpg

OK, Here is the issue and specs.

I have a 06 Commander with a Hemi and about a 1000 miles ago I upgraded my exhaust and Intake. (9,800 total miles on the Jeep)

Before the upgrade I was getting 17-18 mpg on highway trips and now I'm lucky to get 15-16 mpg on Highway trips. I did reset the computer after the upgrade.

Has anyone else experienced this or know what the deal is???

I never thought my mpg would go down when I did the upgrade.

Thanks, TexasHemi
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post #2 of 6 (permalink) Old 07-25-2007, 09:19 AM
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Re: Need Help - Magnaflow mufler and K&N Cold air intake upgrade issue with mpg

Well, are you pressing the gas pedal more to get the rush of the added horsepower? Also, if you are running your A/C more now due to it being summer it can effect your fuel economy.
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post #3 of 6 (permalink) Old 07-25-2007, 10:49 AM
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Re: Need Help - Magnaflow mufler and K&N Cold air intake upgrade issue with mpg

Mine is bone stock and I can't coax more than 16 mpg out of it on the highway!! I think the intake should have helped a little, but I am unsure what effect the exhaust would have, if any, on fuel economy, so it does seem strange that you have noticed a decrease.
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post #4 of 6 (permalink) Old 07-25-2007, 11:49 PM
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Re: Need Help - Magnaflow mufler and K&N Cold air intake upgrade issue with mpg

What happens when you add these things is that it lets your engine breathe easier, allowing more horsepower to the wheels than trying to take in more air. But if you step on the pedal a lot, the engine adds more gas than stock to correct the air/gas mixture. If your computer decided that it need more gas instead of working less to correct the mixture, it would suck more gas and lower your milage. If you stepped on it the first few times after you cleared your computer, this could have possibly happened.
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post #5 of 6 (permalink) Old 07-26-2007, 02:48 PM
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Re: Need Help - Magnaflow mufler and K&N Cold air intake upgrade issue with mpg

Try insulating intake tube and IAT sensor and then isolating the air filter from hot engine air. I noticed at most 2 mpg gain from stock. Initial mod just gained 1 mpg and now 1 more mpg gained so a total of 2 from stock. It was good during the cold months but as Texas was warming up, I felt I was losing mileage and power until I insulated the intake tube and IAT sensor. Still I was not satisfied so I isolated the air filter compartment just like what the OEM box was doing. The only problem now is that the looks are not very professional. Try AFE Stage 2 CAI since I believe they understand more the air temperature and isolation but that is another $300 to spend.
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post #6 of 6 (permalink) Old 07-26-2007, 04:35 PM Thread Starter
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Re: Need Help - Magnaflow mufler and K&N Cold air intake upgrade issue with mpg

Jeepney1

I take it your in Texas also?

Did you install a new IAT sensor or just relocate in air tube?

Can you e-mail me pics of you intake system for ideas on how to modify mine. [email protected]

I was thinking on wrapping the intake tube and air filter shield with a radiant Barrier tape. Along with fixing the gap on the k&N intake shield.

http://www.jegs.com/webapp/wcs/store...10002_72308_-1

Thanks again for the feedback,

TexasHemi
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