I own a 2003 Dodge Neon SE, which I bought like 4 months ago from a dealership. Within 2-3 weeks of owning it, it started to act funny. I noticed the acceleration was pretty crappy and I got bad gas mileage as well. I thought it was cause I needed an oil change, so I waited to do that, but it wasn't that. Then more down the road I noticed my whole car started to vibrate really bad. So I took it to Firestone to get looked at, because that's who deals with the warranties where I bought my car.

They told me nothing was wrong with my car and they can't check it unless the check engine light is on. So I was like, can't you feel the vibration? They told me to get my tires balanced and rotated and that'd fix the problem. And I told him how I'm getting really bad gas mileage and that my car doesn't accelerate right. And he said 20-22 is normal for a Neon, but my car doesn't even get that. The other day I drove 60 miles on the highway and it took a quarter of a tank, when normally I could drive 90-100 miles on a quarter of a tank. And today it took me probably 20-30 seconds to accelerate up to 25 MPH, when before it wouldn't take that long.

I got my tires rotated, and they even did a brake diagnostic and said my brake pads were fine and were where they need to be, and I even got an oil change and they checked all the fluids and they were okay. I did that, but then I noticed after that, my pedals vibrate really bad and it feels like something is grinding, cause I can feel the grinding when I'm driving. I can even hear the engine loudly. It sounds like a roaring type noise. Almost like it's trying to suck in oil, but there isn't any oil to suck in, which isn't the case since I just got my oil changed on Friday.

I read on another message board that the vibration could be caused if the engine isn't aligned right, and then the acceleration could be because either it needs a new fuel filter or the transmission needs to be looked at, but I need more to go on. Firestone won't fix my car until they know what's wrong with it and I think for 795 dollars extra on top of what I'm paying for my car, they should have tried to find the problem.

 

Getting the wheels/tires balanced is always the 1st thing to do when you notice vibration problems. I'd start there.

As for your acceleration/poor fuel economy problem... it could be almost anything. I'd start out by giving the car a complete tune-up. (filters, spark plugs, wires, etc).

 

I thought balancing and rotating tires were the same thing? What does balancing the tires do?

 

Even when new your wheels/tires arn't balanced. If you spin something at high speed that isn't balanced it'll wobble. All tire shops have a machine that will measure the inbalance and tell the guys where to place weights on your wheels to balance it. It's something that should be done every time a new set of tires are mounted.

Sometimes the weights can fall off causing wobble, or you can slightly bend the rim..things like that.

 

Right on.
My old Saturn has a ballance problem. It was only evedent when I got upto around 70mph then the whole car would shake.

If the check engine lights isnt on there are two possible problems.
1: the check engine light is broken.
2: there is an issue with the sencors and computer system.
My Californian Geo had a problem with is (up or down stream, who knows!) emission sencor. The computer adjusted the fuel and air mixture to try and ballance the apparent problem. This set things right according to the sencor. But my fuel milage went down from 40mpg to just under 20mpg. It took me three weeks to find the issue was a sencor not a mechanical problem.

Id go with the above suggestion.
Do a tune up.
Clean/replace the filters. replace the plugs and CHECK the old ones for issues. Replace the wires. Oil change, and perhaps an engine flush?.

Ah, one issue I had with my Metro. I lost power, it took ages to accelerate, and it felt generaly sluggish even with the AC off..... A little research revealed the Cat' had colapsed and I had been blowing bits of it out over SR17, and could hear it rattling around in the muffler. It was a 80k (or 180k i could never find out) event.

 

When you mentioned the computer system, that totally had me thinking. My car is equipped with an anti theft device but it also has a thing in the system so if I don't make a car payment, my car won't start, cause I have to punch in a 9 digit code everytime I make a payment.

I didn't realize I had to punch in a code when I made my first initial payment, so I was at a relative's house for Easter and my car wouldn't start when I needed it to, so my step mom's brother rigged up something so my car would start. He would touch the starter with a screw driver and attach a piece of wire to it and touch the battery with it. The 2nd time I tried to do it, the starter started to smoke.

Although the problem with my car started before that.

Could that have something to do with the computer not working right?

But other than that, that's all I can think of. But I talked to the manager from where I got my car from and he told me to take it to Glenbrooke Dodge, which is part of where I got my car, and their service dept is going to look at it and hopefully figure out what is wrong.

I don't think the guys from Firestone wanted to waste their time trying to figure out what was wrong with my car, so hopefully the people at the Dodge place can figure it out since they know Dodge cars.

 

I took my car to the Dodge dealership and they said there's no mechanical issues wrong with my car. But I do need all new tires since the tread is different on all 4, so the place where I got my car is just going to charge a miscellaneous expense and put it on my loan, and I'll need an alignment too.

So we'll see how my car runs after the new tires are put on and aligned.

And the poor fuel economy and acceleration was due to the fact I drove with the AC on.