I hooked up cables wrong when I first tried jump starting it-then I bought a new battery and it starts fine but now it won%26#039;t idle. What could have been damaged when I hooked up the cable backwards?|||You may not have done any damage. Often when the computer looses power, as in the case of a dead battery or when it has been disconnected, it looses it%26#039;s %26quot;memory%26quot;. Take the car out and drive it for a while. The computer will %26quot;relearn%26quot; what was lost and the car should begin to operate as normal.|||The only thing I can think of is you have damage to your cars computer.
Get it checked out, it could be the problem.
Possibility of a fuel pressure regulator problem.
Also a faulty Idle Air Control motor (IAC) could cause the problem.|||Bad news--the most likey cause is your car%26#039;s computer, one of its most costly components. Take it to a dealership or someplace else that has the necessary equipment to test it.|||What is the make and model of your car? This can help your answer because newer cars have on board computers to maintain efficiency of the motor . Most likely when the cables where hooked up wrong that something electrical was damage.|||You can get a diagnostics box from a local car parts store for around 20 bucks. Some makes have a blinking light system that checks the cars computer when you insert the master key and turn it on. You can take your car to a garage to do this, but it will generally cost between 100-200$ for the diagnostics. Any box or master key will also come with instructions to read the code that is emitted from your cars computer. I could go on, but that is the easiest and cheapest way to go. Even if you can,t fix it yourself, if the auto shop knows what you need replaced(show them the result of the codes) it will save you money. Chances are the computer code was changed when you did this. Best of Luck to you!!!! One more thing. Try unhooking your battery for about one half to one hour. Your onboard computer may reset to original settings.|||Most car computers have to relearn their default programming for idle speed and shift points after you disconnect the battery. try turning it on and driving for a while, then turn it off, turn back on and drive again for a while....do this several times in a quiet area like a subdivision and the computer should reset itself. Next time you replace the battery, run some leads from another battery or car to your battery cable terminals or junction terminal before you take them off to prevent this from ocurring....some parts stores sell a device that plugs in the cigarette lighter socket and runs off a 9 volt battery for this purpose also. Hopefully, crossing the cables did not damage any electrical component.|||Gday, first check your fuses may have blown one and its a 2 dollar fix, If your car is carby fed, check the cables running back from the battery there probally fried, if so you will have to replace them, Had it happen to a friends magna and my 4b, and that was the prob, not hard to fix if you buy more cable to whatever lenght, cut it back in the car and re wire the new cable in its place re fit the terminals, only attempt it if your confident enough as there may be replaceble parts and so on you can get off the shelf in a shop, as this is a quick fix and will void all warranties and may make it worse if not done properly. if not take it to a elec%26#039;y, but i would check the fuses first. Hope it helps.
