1996 Dodge Neon please help

Computer bad?
Maybe but white smoke is more likely a head gasket
running rough with white smoke I would suspect a bad head gasket
should have it checked by an independent shop
and get a documented as to what is wrong and call the dealer where you bought it from and let them know you did that and you need them to fix it and or you will and send them the bill for the repair
do not drive it the 30 days as if you do its yours and have no leg to stand on if its end up in court

BMRFIXIT hit it on the head. Head gaskets are common on a lot of late model cars, and aren't such a big deal anymore. About four hours labor, plus parts. In addition, the cylinder head must be checked for cracks or pitting, but these aren't as common as the head gasket.

This problem can show up suddenly, but it is strange it happened right after you bought it. It's possible the gasket had been corroding through, but just needed the extra oomph from the cooling system building up normal pressure as the engine warms up fully. (White smoke out the tail pipe is typically antifrreze or water being burned in the engine). I can't think of anything the dealer could have done to hide the problem from you just to sell it. Had they known there was going to be a problem, they would have sent it to a dealer-only auction or they would have fixed it.

I ran into the same thing when working in a tv repair shop. We could have a used tv that played fine in the shop for months, then develop a problem within days of selling it.

Not sure what the bank has to do with them taking back the car, but it's not often you hear of someone successfully returning a car. You have to remember there's a lot of expense involved when dealing with the paperwork they have to send to the state, and the government will never give a refund like a business would. You might ask if they will trade for a different car. I personally would jump for joy if I could find a Dodge Shadow or Plymouth Sundance. They are WAY tougher than a flimsy Neon. My friend's took a hit in the driver's door from a much heavier rear wheel drive car with a V-8 engine going 35 mph. The interior trim panel never got touched! Those cars were built like ostrich eggs. The Neon, like all other similar cars, are much lighter and weaker in an attempt to meet federal fuel mileage requirements. You might die, but what's important to the government is good fuel mileage!

GM front wheel drive cars are much worse. A Chevy Cavalier and a Pontiac Grand Am collided near my house. A county deputy was following one of them and witnessed the crash. Both cars were going 45 mph on icy roads in a 55 mph zone. All four people were killed, two in each car. All had their seat belts on. Since then I've been paying closer attention. When people are killed in a crash, it's almost always in a GM front wheel drive car.

Neons fare a little better it seems, but they're still nothing compared to the Shadow and Sundance. Also, if you're looking for reliability and cost of repairs, the older the car, the less it's going to cost to fix it. As an example, if the power windows would ever quit working on my 1988 Grand Caravan, I can fix the ten dollar switch. When there's a problem on my mother's 1995 Caravan, it will likely be the $400.00 body computer. Her dome lights don't work now. The new body computer will fix that. Ford products involve two different computers to honk the horn! This computerize-everything-possible nonsense is one reason people aren't buying new cars. They've been bitten too many times by ridiculously high repair bills.

Caradiodoc