Shifty Powers

So i was at the track and after i actually got there my cars idling would randomly drom from 800 to 300-400 then back up.... so i was a little cautious with her...when the car did this it felt like she was going to stall....

when in line for my 4th run i pulled out... car was making funny noises and was overheating and battery seemed liek it was gettin a tad low.... i pulled back into where we parked our cars... revs dropped from 800-300 about 3 times and on that 3rd time the car just died(battery light was on)..i was later able to start her but the batterys charge was still low..so i called a flatbed and brought her home...when we got home.. she started right up and everything was normal on her....

mind you my 96 cobra is all stock/all original that i know of... with 115k miles... i thought it was the alternator... but i could be wrong.... but if u think the same, could u possible stear me in the direction of a good alternator please?

if u guys think otherwise please let me know what it might be and where i could find it...

Thanks in advance

Shifty Powers

anyone? course it is during the day...

Billywrd

It sounds like the altinater, but I would take it to have it checked to make sure. Sorry, but I have all of mine rebuilt by a shop near my house, so I can't help more than the obvious parts stores.

Brute03

to see if its the alternator start the car then disconnect the negative batt. terminal and see if it acts like its gonna die or just dies completley, but it's best to get it tested to know for sure.

HaV

Doesnt really sound to much like an alternator to me, but I can tell you an easy way to check. Do you or a friend of yours have a Multimeter? If so just test your battery when the car is off. Turn the car on, and give it a few seconds (you might have to jump it if your having power issues), then test the battery when its running. Turn the car off, wait about 3-4 min, then test again.

You dont really even need to know the numbers.. just whats happening to them. Set the multimeter to volts DC. Just for reference my battery is at 12.4v right now sitting.
Its your battery if: Your numbers are low to begin with, go up quite a bit when your running, drops when you turn it off back to where it was.

Its your alternator if: Your battery is putting out normal numbers, drops when you start the car, and comes back up when you turn it off.

Normaly you should see around 12v when sitting, around 14 when its running (its getting a constant charge from the alternator so its running higher), and back around 12 when its off. You want to make sure nothing on the inside of the car is on when your doing this test.


Thats not 100% accurate but it gives you a pretty good idea. I have had to figure it out on my own many many times on my older vehicles.. I knew it was a power problem becuase I had to be jumped every time it acted up.

Your problem doesnt sound like an alternator to me.. It honestly sounds like your fuel filter clogged up on you, or is trying to clog up on you. If its not your alternator or battery, replace your fuel filter, and run some injector cleaner through it and see if it helps any.


Hope that helps ya!

70 MACH I

Eliminate the battery as suspect first, alternators require a good battery first to charge. Disconnect your coil to ignition (12v square plug) and unplug fuel injector harness (you don't want to pump raw gas in cylinders) put voltmeter across battery, crank engine. If battery drops below 10V while cranking, battery is NG. Replace battery, check for charge with voltmeter across battery, should be 14V approx. Another hint of bad battery, losing radio presets. I had a T-bird doing this. When I would crank it over battery voltage dropped below 9V, tripping my presets. Hope this helps, John

Shifty Powers

according to my guages my battery is almost dead now... although my car as of friday night still turned over.. i have yet to try again.... i will start testing it this week and have it checked out.. thanks guys....

monkeydude3

okay if the battery light came on your alternator is toast. In my experience the only reason that light comes on is when the alternator isn't charging enough!!!


Simple check. Voltmeter on battery with engine off. Should be 12.4+ volts (12.6 optimally)

Fire it up. Voltage should be 13.5+ volts (14 or so optimally)


easy way to pinpoint either. It sounds like the alternator. Technically, you should be able to pull the battery out and let the car run on the alternator (not for a long time ) but that is what todays' alternators are designed for... so when your battery goes and you get a jump, you can drive to a shop!

George

Shifty Powers

well it starts and drives now.. with a full charge on the battery... were thinking the alt is going on and off and will just die.... cuz when i was at the track my car was getting quite warm... and when i would stop on the gas and rev it, it would cool down and go back to normal temp... i think once i get the money and fix things im gunan grab more guages too keep a better eye on my car(not anytime soon).....

but yea were gunna go take it to get looked at soon

monkeydude3

yeah have a "vat 40" test done. Simple test where it loads the battery, then you start the car and it loads the alternator. This will tell you easily if one is bad, we have one at my work


George