The wife bought a 2003 Dodge Neon SXT ( automatic) a few weeks ago. We figured it would be a commuter car and get decent mileage. Well, it doesn't. It seems to get right about 20-22 MPG even on the highway. It is throwing a code P0586 which is the "Speed Control Soleniod Circuit" Which I am guessing is why the Cruise control isn't working but I have no idea what it actually is. Any ideas why the mileage is so bad and a possible remedy?

 

I would start looking at the idle air control, which is at the air intake on the manifold. A Chilton's manual would be a good investment on a used vehicle. The parts store would probably help you out with codes too. It'll probably also want oxygen sensors pretty soon.

 

P0586 would refer to the cruse control for that vehicle.

It does look like you are a few miles short of where everyone else is at.
http://www.fueleconomy.gov/mpg/MPG.d...rue&details=on

So a few questions for you.
What is it idling at?
What temp does the dash gauge read?
What is the airpressure in the tires?
What does the air filter look like?
Can you feel it go into overdrive?
What does the trans fluid look/smell like?

I think that is enough to start with. You are about 7 mpg off on the free way from the average, so its not horrible yet.

 

'Nother question or three...how many miles on it? Since it's an auto, has the fluid been checked and/or changed? What RPM is it cruising at?

 

My 99 five speed gets anywhere from 36 to 44 on several ocassions. I think I'll keep it.

 

Might have a look at the Oxygen sensor too. When those go they default to the rich side so no damage occurs just poor performance and mileage. Other things would be the plugs and wires. Not sure about the interval on those or how many miles you have on the car but that's something else you might want to think about.

 

O2 Sensor would through a check engine light though.

 

My wife's 2003 Neon automatic gets about 18 mpg in town in the winter and 20 mpg in town in the summer.

On the highway, it gets ~35-37 mpg.

The low in town mileage is directly proportional to the 1 mile commute to work.

 

My 2003 Neon RT gets 28 mpg Best was 30 mpg

 

Well, I haven't tried anything to remedy it yet, that is why I asked you guys, as a starting point. The car has 60,000 miles on it and no i haven't checked the trans fluid yet. After talking to the wife about it I think it could be in the fuel system. She said she smells gas once in a while.

The car seems to cruise very nice and it doesn't overheat at all. The shifting is smooth. Everything seems as it should, until you watch the fuel gauge!!

I am going to change the fuel filter, air filter, plugs and wires tonight and then go from there.... Thanks for all the ideas.....

 

If she is smelling gas every once and a while it could be something to do with the fueling. Take a picture of the plugs when you pull them out. Dont clean them up first either.

 

OK I just found out that the fuel filter is inside the gas tank. What is the deal with that? how are you supposed to change the filter then? oh thats right the dealership..... SO hopefully that isn't the problem

 

Lift up the back seat, there may be an access hatch. Probably not though. Save it for last if there isnt a hatch.

 

If you can get onder the car at all, you might want to check for a loose or cracked fuel line. I'm wondering if you're not leaking gas from a bad fitting or something.

 

Man thats not very good, I'm getting 28.4 (mixed driving) in my 2004 Neon SRT-4 and that includes 1 drag race in which I embarrassed my father in law in his 2003 mustang gt...