Battery/electrical help.

computer issue? from the way you described the gagues going all wonkey at idle, it sounds like the comp has some issues... possibly a short somewhere that also is causing the bleed off of power. for grins pop the BMW battery into the stang and see fi it does it. after the test remove it immediatly and put it back in the BMW (dont want the cobra to eat a second battery).

did the gagues go all over again? still reading off in the volt gague? if so then its time to go ahead and try some light electrical work, check the power chain: chasis ground to battery neg, battery pos to alternator pos, alternator neg to chasis ground. make sure all are corrosion free and secure, double check all the wires and even ohm them out to see if there might be internal wear on the wires and possible even eaten points in the line.

if all is well on that front then check th grounding wire near the computer in the passenger side foot well. then go ahead and pull the gague cluster and check to see if you can visually see anything wrong.

this is about all i can think of without getting my hands on it myself.

Torinalthq

I say bad battery (possibly alternator too). A bad battery can kill an alternator and vice versa. So, if possible, have an auto parts store load test your battery and test the alternator, then you can rule those out or confirm that they are toast. If you buy a new battery, put it in, and the alternator is bad, it will just ruin your new battery (most likely). I'd have em' tested then go from there.

Once your car gets started you can run it directly off the alternator without a battery. If that don't work, your alternator is bad.

Sounds like the problem is the voltage regulator, but that's built into the alternator.

Alternator is bad

Ok heres the deal. Your alternator is bad. When the regulator inside the alternator failed it let the alternator overcharge and overheat your battery. I bet if you open it up and look inside all the water and acid will be nearly gone. Your computer might be ok eaven though it was overpowered. The gauge sweep thing is normal when the computer resets to factory settings. It was reset because the battery was damaged and could not supply enough power to keep the memory.

The solution: Have the battery and alternator tested where you just bought them. That way you can have proof to them they are bad.

Let us know what you find out.