Dodge Neon low mpg
 

Im pretty sure this is the place to post this. If not, im new here, sorry :). Ive browsed a few times, im just not a big forum poster.

Anyway, I have a 2003 Dodge Neon SXT automatic. I got it...July? Wow, I completely forget. Well, I definitely got it less than a year ago so the only way I know im getting low mpg is by reading the official specs (and not experience driving it). I get an average of like 20-22 mpg and live in a suburb type area. Not quite city style driving (constant stop and go), but way too many stop signs to be highway style driving. 3 days a week I travel about 35-40 minutes on the highway to and from college though. I think its rated for 22 city, 29 highway, so im barely making city mpg even though im not driving purely in a city-like environment. There are people who are apparently getting around 30 average, even more. Ill try seafoaming my engine before I get my next oil change, but I have a feeling it wont really make much of a difference. I will also someday upgrade to an aftermarket cold air intake and a performance exhaust, so that should help by a little. However, I want to fix this problem first before I do that. I shouldnt have to buy aftermarket stuff to bring my car up to factory specs.

Here is as much detail as I can give you guys:

-MPG manually calculated by dividing miles driven by gallons put in.
-Careful driving, rarely hard accelerating.
-Tires are 195/60R16, inflated to 40PSI.
-Front tires will probably need changed after or before the winter, but the rear ones are nearly as good as new.
-Unknown condition of spark plugs/wires as well as fuel injector and alternator.
-Intake filter seems a little dirty, but not enough to need changed.
-Transmission kept sticking in 2nd gear about 3 or 4 months after I bought the car, but new solenoid seems to have fixed it.
-Oil is currently in good condition with maybe around 1,600 miles on it.
-Odometer reading of over 106,500 miles.
-No holes in exhaust that I could find.
-Using mid grade gasoline (89 octane maybe?) and filling up to full (around 9 gallons) each re-fueling.

Hopefully the problem is just a simple matter of catching up on maintenance. However, if what im getting is what im supposed to be getting, then how the heck are people getting a lot more with little to no modifications? Im not the best eco-driver in the world, but I still try. Accelerating steadily, keeping foot off the accelerator pedal on down-slopes and whatnot. Ill floor it at stop signs/red lights maybe one or twice per tank (I know, I know), but is that one or twice really making that big of a difference in fuel economy?

Oh, speaking of hard accelerating, I think I should bring this up. I tested my 0-60 time once on a chilly night and got 10.5 seconds. I think its factory rated at 8.1 seconds, so im obviously losing some power (and possibly efficiency) somewhere. The question is where. I know those couple hard accelerations are affecting my mpg to some degree, but that loss of power is raising some red flags. I have the philosophy of, as long as all the parts are either replaced or kept in good condition, a car should perform just as well as if it were brand new. Power and efficiency dont just disappear out of nowhere.

No solutions, huh? I guess ill try some basic maintenance then even though it all seems fine, other than the low mpg and slight feeling of sluggishness...

injector cleaner and new plugs. could be a crappy alignment.

any check engine lights on?

Has the tranny fluid been checked?
don't leave this one alone i have felt no difference in driving between no fluid and full fluid, and it should've been changed at least once by now as normal maintenance.

Does it have any problems...rough idle, pulling to any one direction, etc.

A car will almost never perform as new with time and age parts will begin to get buildup such as carbon and will begin to lose power. These parts can be cleaned or replaced to return back to new though

If the plugs have never been replaced, they are likely due. Pull them and do a visual and check the gaps. The suggestion to check alignment is good too.

At 100k miles, many maintenance items are likely due. Check the maint schedule in your manual. If you have a timing belt, that may be due for replacement too.

Low power or fuel economy can be caused by any number of things. A Chilton or Haynes book will list possible causes and have instructions for performing the maintenance tasks.

No check engine lights and transmission fluid is fine. I checked that and its at the right level. Idling also sounds good, maybe a very very slight knocking sound, but its hard to notice. Strangely though, the oil light came on a few times as I was driving home yesterday. Hasnt done that since. Driving in a straight line, it does pull to the right just a teeny, tiny bit. As for cleaning the injectors, ive tried Gumout before. Seafoam will be next.

I forgot about the timing belt. I read that these cars could use a replacement after 106,000 miles, which is where im at. Expensive though...but im sure its better than my engine quitting in the middle of the highway. Ill look at the spark plugs too. The thing is though, it was having a missfire before I bought it, and since it was fixed before the dealer sold it to me, he might have had the spark plugs and wires changed. Wouldnt hurt to look anyway.

As far as the little bit of knocking at idle, most neons shake and knock to some extent, they all seem to have a rough idle. I am guessing that when the oil light came on, you were going around a corner to the right? Did it go off right away after the corner? If so, that means your engine oil is a little low, and when you turn right, the oil sloshes to the left away from the oil pump pickup, causing temporary low oil pressure. Top up your oil and you will be good. That may help your slight knock a little bit too.

My neon misfired and threw a check engine light when I got it, was a plug wire. Do your brakes drag? How tight do you have your rear drums set?

the oil light if it comes back on with topped oil level is a bad thing. It happened to me on a past car the oil light came on and the motor started ticking badly, the oil pump had quit and in my particular car 96 taurus there was 2 options to fix: pull the motor, or remove the exhaust. pulling the motor wasn't going to happen and to remove the exhaust it had to be cut. this caused it to be scrapped

Stratus had interment oil light coming on last year, sensor went bad and was leaking oil, pretty easy fix. Hope it's that.

Im assuming no spots should be underneath a car whatsoever, no matter how small. If yes, then yeah I probably need something to do with my oil fixed. Sensor, pump, hose, whatever. Ill check into it soon. Engine temperature stays rather cool, so I doubt its the coolant. But yeah, 2000neon, I think I was turning right. It didnt immediately turn off, but it didnt last long.

None of my brakes drag (that I know off), but the rear ones arent tight at all. Basically if my front brakes ever malfunction while im driving, im screwed.

Actually now that I think about it, ive been having this sort of mpg every since I got the car and the oil level was perfect then. Gahh, friggen oil and timing belts. Id go electric if they could match the same range and power...and price. Im kind of eager to get everything checked over soon to see if simple maintenance was the problem. I suppose I could go ahead and do it early... And if it is a wearing out timing belt, thats something I need fixed immediately. What should I look for in terms of wear and tear in a timing belt that might not be obvious? I dont have any experience doing this :).

Gealii, do you mean just replacing the exhaust system? Because I was going to do that anyway for performance and aesthetic reasons. Not any time soon though.

EDIT: I just went outside to check the oil level and its right on the max line, though I remember it being a little higher last time I checked before. Its also getting a tad brown. I also have an MSD ignition coil. I dont know when that was installed. I know I didnt do it. Not that I forgot to mention it before, I figure I might as well now since I was just under the hood.

it was the headers i had to cut beings i could not get anything up next to the bolts to loosen them. the rest of the exhaust was fine. replacing normal exhaust does not include headers so hope you never have to do this if you drive easy u shouldn't have to. The only reason mine quit was because everyday after school i would be doing about 130mph bumper to bumper with 2 other kids...never again and the oil pump quitting was actually what got me into ecomodding so i guess i should be thankful for it

Timing belts will show small cracks around the teeth of the belt. BUT.. Just have it changed. Its expensive, but at the same time, its cheap insurance. If the belt breaks, it smashes most of your valves. At least 4 of them. This repair is much more expensive.

Have an alignment done. Older cars tend to start sagging in the spring department. This tends to change camber and toe in/out, causing drag.

Have your oxygen sensors checked. If these start going bad, they tend to fail rich, = more fuel.. less mileage.

Make sure your thermostat is working properly. The new style T-stat fails open, causing the engine to run cool throwing off the fuel mixture.

Tune up.. plugs, wires, and air filter if you haven't already.

Use a quality fuel injector cleaner such as Techron. This will do wonders if the injectors are dirty.

Seafoam.. Only pour it in the tank and in the oil. NEVER suck it in the engine via a vacuum line. It could pool up and get sucked in the engine and hydralock it.

A thinner weight oil will help a little too.
Hope this helps.
Good luck!

My dad knows a mechanic that will change my timing belt for $300. He's the one who replaced the speed sensor and solenoid. Ill check the condition of the belt when I get back to the parking garage my car is at (im sitting in class right now).

As for alignment, ill have that done when I get my new wheels on. Theyll need new tires, so once these wear out, ill buy and mount new tires on my new wheels and get an alignment the same day. And im going to get lowered and stiffer springs eventually (1.5" lowered at the most), so I think it would be a waste of money to replace my current ones and then replace them again with the lowered springs. There doesnt seem to be any sag right now anyway. They seem to be in good condition.

When you say that engine temp stays cool, how do you know? If it is by the factory temp gauge, on my 2000 it only showed about 1/3 of the way up the gauge. There were two marks, one about 1/3, one about 2/3 of the sweep of the gauge. Mine always ran right at the lower 1/3 mark or just a hair above. I always thought it looked low (would assume it should be right in the middle) but I guess not.

Most cars have 2 temp sensors. 1 for the gauge, and the other for the Fuel Injection. They usually run between $7-$20 depending on the car. If its running low, you may think of a new thermostat also.
By the time everything is all said and done.. you'll have a pretty reliable little car. ;-)

bad Thermostat can cause this terrible gas mileage.

Had couple fleets I notice summer it was great on gas but the colder outside it was WORSE and notice it get longer to warm up it turn out thermostat wasn't work correct it let engine running cold make computer think cold need injector more gas gas.

Im not sure where the needle should be on the temperature gauge, but it looks low to me. Even after driving for half an hour at 55mph+ speeds, the needle is about at 1/4. Actually, heres a perfect picture I found of what it looks like. Mine is just a little bit higher than the one in this picture. http://www.thecarconnection.com/imag...rument-cluster
Does that still seem suspicious? Well, im glad the replacement parts are cheap.

How exactly would this effect gas mileage though? I mean, I completely understand things like faulty spark plugs or clogged intake filters causing a problem in efficiency, but a thermostat or temperature sensor?

Hmm so it's a 1/4 way up on the gauge? Yeah that seems low to me too. I don't have the car anymore so I can't even go out and check, but I know that mine never made it up over 1/2, except when it overheated... Anyways, it always drove at just at or slightly above the mark at 1/3 rd of the way up the gauge (assuming your gauges are the same as mine, but I think they are). There is an old school way to check if the thermostat is working, stick it in a pot of water on the stove and crank the heat, you should see it open. And use a meat thermometer to check temp.

You know the two thin lines between the bold ones? Mine never seems to go past the bottom thin one. Maybe thats more like 1/3 actually.

As a reference: My gauges looked like this,
2002 Dodge Neon Gauges Photo #47448868 | GTcarlot.com

My temp gauge was always at the second line, the one a little below half. So anyways I guess my point is, even if it seems low on the gauge, it may not actually be, see if there is some way to verify the temp or where it should be.

Well now... This might be helpful. I found out how to see error codes and I got 456 and 440. I think 440 means theres an EVAP failure and 456 means an EVAP leak. I could be wrong though. I only looked on a couple websites.

thats right where it should be.

evap systems are a pain to deal with...i had an evap leak on my old car and i replaced all but the lines to have fixed the problem it would have involved replacing all the lines including the gas filler neck

Im starting to feel like I got ripped off with this car. I expect things to happen to it, but not this soon after buying it.

Update
 

Im bringing back this post, but I thought id give an update.

The only thing I did was change the oil. Ive since increase my mpg to 24 as long as im careful. Whoo! Pathetic still, but hey, better than 22. Also...I just realized something. The station I always use to fill up uses 10% ethanol. Big sticker on every pump that I somehow missed. Now I know I still have some maintenance to do to get my car back to its proper efficiency, but that ethanol mixture is definitely lowering my mpg.