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Sporadic Idle and Eating Batteries????

639 Views 7 Replies 4 Participants Last post by  brad81987
SOOO FRUSTRATED!! :boid::cursin::tdown:

I searched the forums, but couldn't find an answer to this.... Please help!

I have an 00' Rango 4.7L
Truck idles wierd up and down between 800rpm and 1500rpm. It literally looks and sounds like I am revving it but I'm not....
I am not sure if these are seperate problems, but I figured I'd put them here in case it helps to diagnose....
A few months ago, Rango drove fine, started right up, went to the store (maybe 20 mins inside) came out and the truck wouldn't start. Battery was completely dead. Strange considering I was in there for a very short time and left no lights on or anything.... but ok. We jumped it (took a good 20 mins to get enough charge to even start) and drove about 1/2 mile when the "check gages" light came on. The battery gauge was reading 18!

Took it to Advanced (we were literally 10 yards away when the light came on) parked, and cut the engine. Truck wouldn't start back up again. Advanced says we need a new battery, ours is shot. So we buy one and install it. Truck starts and runs fine.....:drive:
SAME thing happened last night.:rant: The battery is getting an OVERCHARGE....We haven't replaced the battery again yet.... because it HAS to be something else....
Any ideas????
We thought starter...but it when it has a charge, it starts right up.:huh:
we thought alternator.... but, when we did the power steering pump about a month ago, we ran the truck for about an hour on just the alternator (battery died and we wanted to see if that was the issue. It wasn't. Hood light killed the battery. Jumped it, and we were good to go... until last night that is....) :huh:
So.... Any suggestions????? HELP!!!!!
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Similar thing happened on a 2000 Dakota 4.7L a family member of mine had. According to my wife's uncle (certified dodge mechanic) there is some sort of memory thing in the PCM that "remembers" Jump starts and bad batteries and causes the rough idle. For the Battery dying thing, the truck was owned by my wife's grandfather, I t/s it down to a short in the trailer brake assembly. For some strange reason the trailer brake was draining the battery. I hope this helps, as far as fix goes; I'm not sure because to make a long story short, the old man died and his wife traded in the truck...

I would have the parts store check the battery, and the alternator. then start looking at things that may have a short and cause them to run all the time, i.e. hood light, brake controller, radio, etc...
Well... Battery is fine. Alternator seems to be fine.... We replaced the negative battery connector, cleaned the terminals, and she started right up. no issues as of yet and it's been 3 days. Still idling funny, but we're thinking maybe a vaccuum leak..? Thanks so much for your help! I just love this forum! It's the first place I go when answers don't come right away!
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Give a few more days on the funny Idle... might clear up, also you should check your IAC on the throttle body and make sure that it's not worn out... Happened to me on my Ram, pulled the IAC out to clean and the thing fell apart in my hand...
Same thing happened with my IAC and it was just replaced. also the TPS (got the code, and replaced) .... The TPS went on it today and we replaced that. Seems to have cleared up the funny idle (only after having to drive on for 2 hours :cussing: ) and NOW (for the finale... if you haven't had enough of my truck!!!:banana2:) There is power steering fluid leak. looks like it's coming from the bottom of the reservoir.... CAN'T FIND A RESERVIOR!!! :fail2::boid: ANYWHERE!!!!:cussing: Any ideas on where to get one??:huh:
Rockauto.com ?
or check car-part.com it's a junk yard search, although some yards don't list anything or everything they have...
go to oem catalog and search if you dont find it call them
....we ran the truck for about an hour on just the alternator (battery died and we wanted to see if that was the issue. It wasn't. Hood light killed the battery. Jumped it, and we were good to go... until last night that is....)
In you case you seem to have gotten away with this, but general practice is you should NEVER EVER RUN YOUR ENGINE WITHOUT THE BATTERY!! Your alternator output is not smooth. It's rectified 3-phase AC. The battery acts as a giant filter to smooth out the alternator output and harmful spikes/harmonics. Without the battery, these spikes could cause damage to electronics in the electrical system. I'm not saying it always will, but there is always a chance. Play it safe and don't do it. There are other much safer ways to test your alternator.
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