Idle problem..strange

[raysum]

I have a 1993 explorer and when I am in drive and idling my voltage drops this is especially noticeable when I have the A/C running. I have watched my volts and they drop briefly and come back up but it continues this pattern.

Here is the kicker, I do not have this problem while driving or the car is in neutral or park. Any fixes? thanks...

 

[Spdrcer34]

In neutral, the idle is a bit higher. Thus the alternator is spinning a little faster, making more charge. Same story with it while cruising. But at idle, while stopped, the engine will have the lowest RPM's it should ever see, and the alternator will be turning the slowest.

Ryan

 

[Espresso]

Mine does the same thing especially when operating the windows. It will dip down to about 8V & then back up to normal. I have done tests to check draw & everything, but it checks normal when I do it. I chalk it up to a funky gauge. I use my system all the time & it doesnt move. But it goes crazy with the windows.

I'm putting in a digital soon, because i'm going to be upping the ante on my stereo system & need to monitor it more closely.

 

[raysum]

Is it possible that my alternator is going bad? The problems did not start happening till several months ago. Their are times while sitting at a stoplight that the explorer almost cuts off because it's idle drops so low....

 

[pgsoap]

i have almost the same problem volts drop then back up,took to auto zone ran test on alt while running came back that i had a bad diode.he said diode will eventually stay open and drain battery.right now still using alt.don't have $160 to replace.

 

[Texan01]

it takes a lot of juice to start an electric motor, which is why when you turn on the HVAC system the voltmeter drops at idle or when you run the power windows up or down or against the stops. or on my car when the electric fan for the radiator kicks on the voltage drops because it takes about 25 amps to start the fan. if you just started noticing this, then your fan motor for the HVAC system maybe starting to go out, the bearings may be worn. otherwise you might have a weak alternator. our you might scrounge up a smaller pulley to run the alternator faster, but you'd have to change belt sizes.

Now what's really annoying is my old Chevelle did that a lot because it had a 63 amp alternator and with the A/C on (30amp draw) the lights and say the wipers , it'd run out of alternator real quick at idle. it took 5 amps to run the ignition system (HEI) to run the car, gotta love a non-computer controlled car (sometimes)

 

[raysum]

Thanks....I tend to suspect that it is the alternator since I have a 93 Explorer with close to 173,000 miles on it and I am still on my original alternator!! I don't guess I can complain to much.

 

[monkeydude3]

I have a 94 XL with 136k miles on it... starting to exibit a similar problem, I suspect my alternator may be going as well