I've got a '93 Bronco 302 E4OD with 75k. Within past two months, new cap, rotor, wires, idle air sensor, yesterday i replaced the EGR valve to cure a rough idle. after reinstalling the neg. battery cable, ran great for the first 10 miles or so. but now after driving, when i place the shifter in park, the voltmeter drops, the revs drop and it stalls out. is my alternator dead? i cleaned the contacts on my battery cable/posts and checked the connections. any ideas? this truck has always ran well...
p.s. voltmeter also drops when lights turned on, so i'm guessing maybe voltage regulator?

thanks

 

or could it be something simple like a dying battery? am i being stupid and overlooking the easy answer?

 

Doug ,
Is it the original battery ? Have it load tested to see whats going on with it . Also check to make sure the fluid level in the battery is ok . Simple way to check the output of the alternator is place a DVOM on the Pos and Neg cables and check what the alternator is putting out ...you should see 13 to 14V .
Paul

 

I don't know if it's the original battery, it is a Motorcraft unit, I've only had the car 6 mos., so it might be orig., no date code on case. I'll have it checked first thing in the morning, I'm a college student and I have a lack of tools, so I've got to have it checked professinonally. Thanks-

 

Doug ,
If Its a Motorcraft its most likely the original battery . A good replacement on a budget if yours is bad is a Diehard from Sears . Thats what is in my F150 and its been a great battery .
Paul

 

Well, the battery and the alternator both checked out ok. The battery is holding its charge, and the engine always starts right up. My local mechanic and I are stumped. Of course, the vehicle wouldn't cut off for him. He doesn't want to replace things that don't need replacing; now he wants the car for a day to test it.

 

Doug ,
Have a look at the battery cables themselves from the battery to the starter with the Neg cable and the Pos one from the battery to the solenoid . Im betting one or both are suffering from internal corrsion / acid migration . The Neg one not only bolts to the starter but also to the frame . Its a bare stripped part of the cable that is attached by a clip and bolt to the frame . Ive seen corrosion work its way along the cable from that point .
Paul

 

could i have a bad replacement idle air control valve? it's a g.p sorenson, should i spend the extra $$ and get the ford oem replacement?

 

Strange though it may sound (knock on wood) the problem seems to have gone away. We'll see though...