Poor Gas milage and suggested improvements

[ptrepoff]

I have a 05 dodge magnum rt. Since I day one of purchase(car was at 32k KM) the car has been bad on gas 7-10Mpg 15-16mpg on the highway. The only thing the dealer will do is update the software on the car to resolve the issue. Which it never does. I am now at 42k KM.

They did suggest that if replaced the plugs, cleaned the throttle body, had a wheel alignment, and changed the air filter they could look into it further.

I have had the wheel alignment, changed the air filter, changed the spark plugs, and ran a product called sea foam through the fuel system. Thanks to the forum I have done everything myself except the wheel alignment.

None have things have made any improvement and the gas mileage does not seem to change whether I drive the car hard or baby it. It seams to miss slightly at idle and if you drive at a constant speed a very slight surging.

I have three questions:

Does anybody have any simple instructions for cleaning the throttlebody?

Does anybody have any other suggestions of what may be wrong or is this kind of fuel economy normal?

After cleaning the fuel system with the sea foam product I wonder if I should change the fuel filter? If so is it easy to do and where is it located?(Near the fuel tank?)

Any information would be greatly appreciated.

[MagnumRT05]

Have the same problem. Although i do race mine time to time against the little ricers, i still get 12.9 mpg when i check it. Even after driving an hour to go to Kent State, its still at 12.9 and sometimes up to 13.2. Like to see what people have to say!

[FloridaRT]

Might be the cold weather you have, makes the car run richer.

Here in Florida, I always get at least 20 MPG in the city, 29 on highway.

Might want to try the Superchips Flashpaq.

Bob

[fnkychkn]

use only a clean dry rag and a finger to clean throttle body (key off).
fuel filter is in tank and serviced as part of fuel pump module. it is not a maintenance item.

[sstevens805]

i've never gotten over 17 on LONG road trips. in town right around 11.

[ptrepoff]

Thanks FloridaRT for your reply. I actually own a Superchips Flashpaq but I really did not see any fuel ecomomy improvements. Since I am trying to get dodge to look into this for me I have decided not to use my flashpaq so that they do not have any reason not to fix what I perceive to be a problem with my car. Those are my summer stats that I have posted.

[MattRobertson]

Are you SURE your oil changes have the correct weight oil, thereby NOT disabling MDS? That would be a mighty simple explanation and a typical bonehead service move.

[DannyC]

Might be the cold weather you have, makes the car run richer.

Here in Florida, I always get at least 20 MPG in the city, 29 on highway.

Might want to try the Superchips Flashpaq.

Bob

That's got to be a record. I only get 19 city and 27 highway in my V6 SXT.

[ptrepoff]

Thanks fnkychkn for your replyI will follow your advice. Is sstevens805's mileage more realistic of what I should expect?

[ptrepoff]

Are you SURE your oil changes have the correct weight oil, thereby NOT disabling MDS? That would be a mighty simple explanation and a typical bonehead service move.

I would hope not 10 w 30 right? Just kidding. I have had my oil changed 3 times since I have owned it I believe but all from the same place(costco) Maybe I should try somewhere else to make sure.

Your right I should try somewhere else to make sure that is not the problem. The rough idle(misfire) concerns me though still.

[MattRobertson]

certainly the rough idle is bad news. Check the Costco receipts to make sure they didn't do something goofy and put in 30wt.

[MagnumFan7]

That mileage doesn't sound right. For me, with a mix of highway and back roads (30-45 mph, occasional stop lights), I see 19-20 mpg. On the highway, after resetting the EVIC, I saw 25 (hey, I hit the EPA number!).

I run 89 octane, various brands.

The rough idle might suggest a vacuum leak. Have they checked for that? Have you tried other brands of gas? Is it possible you have a pinhole fuel leak somewhere?

I hope you can find the problem...

[ptrepoff]

That mileage doesn't sound right. For me, with a mix of highway and back roads (30-45 mph, occasional stop lights), I see 19-20 mpg. On the highway, after resetting the EVIC, I saw 25 (hey, I hit the EPA number!).

I run 89 octane, various brands.

The rough idle might suggest a vacuum leak. Have they checked for that? Have you tried other brands of gas? Is it possible you have a pinhole fuel leak somewhere?

I hope you can find the problem...

They always forget to look at the poor gas mileage when my car is in at the shop. My understanding is that they have updated the pcm and tcm firmware for my issues and that since the car is not flashing any related codes then they say it is likely a maintenance item They have suggested that $800 dollars in customer repairs i listed in above post may fix it. If it doesn't then they can follow up other leads. I have noticed a u110a code myself though that has come up a few times. I would assume if there was a fuel leak I would smell gas, which i do not.

How does one know if there is a leak in the vacuum lines?

After I clean the throttle body then I have completed the suggested maintenance and then i guess the dealership will look into the issues further I hope. I have tried various brands and octane levels with little difference. I had hoped the recommended octane would make a difference. I kinda get the idea this dealership anyways doesn't like to look at poor fuel economy issues. I am sure they get lots of people complaining because it doesn't match the sticker. But i would like it to be somewhere in the same ball park. Especially when so many people in these forums seem to be getting so much better mileage then me.

[gbb]

Our '06 Mag R/T does from 12-14 around town, 21-22 hwy.

Neither the wife or myself is easy on it around town and the hwy mileage is at 70-80 mph. It isnt an economy car, but I didnt expect it to be.

I am satisfied with the hwy, I wish the city was more like 16.

gbb

[Moparrbust]

Now I'm glad I got a SRT-8............my car gets a gas sipping 13.8mpg city. I use the WOT feature quite often as well.