Okay so ive been having electrical issues the last week and my negative battery clap was bad and the ground on the body need to be cleaned up and i fixed it and my battery was charging up and was running at around 13 volts so i got in yesterday and the car was idling at like 2100-3000 rpms and it was raining and then today after driving it around iyt droped back down to normal and then about 3 hours later after it stoped pouring i went to go driving and the car didnt wanna start and the volts were down to 11 and then i put my head lights on and it droped to 8 rpms up to 3000 and the lights were dim any ideas what could be happening ive had the battery and alt tested both are good and there is no slack in the belt oh and its a 88 vert n/a any ideas??

 

So you're here now too I see.

First of all 2100 - 3000 is way too high for your car to be idling and you should get that fixed. Its probably a vac leak or maladjusted TPS or a combination of the two.

Second, The S4 alternator is just weak. You might be expecting too much out of it and the 20 year old electrical system.

Then again there might be an exposed wire or something that's draining the battery when you let it sit.

You could run a new alt ground, but that's just a shot in the dark. You really need to get a multimeter and figure out where the real problem is.

 

The rain is a red herring...has nothing to do with it.

Your system should be running at 14+ volts.
I'd recheck both the battery and alternator.

 

same thing happened to me and i got a new alternator and now have no more problems

 

okay i think im just gonna look into getten a new alternator and go from there

 

i have one more question tho i just figured the car was idling high to like charge up the battery could that be the case because it always goes down after 10 15 mins??