I am going to try this again tonight, hopefully my account and post doesnt just disappear again.

I have a 99 durango 5.9 with what seems to be a idle or electrical issue and I cant seem to track this down. When I first start the D it runs fine, once it reaches operating temp the RPM's hold righ about 580-590. This seems to low to me for this truck. As well the lights have a slight flicker in them when it gets to operating temp. This includes the headlights and interior dome lights. Once the idle gets to the low point of 580-590 it has a slight shack to the truck like it wants to die. It doesnt worry me that it will die just gets that feeling of how a car does when it is going to die.

I noticed the lights flickering first a couple of months ago. Had the battery tested and store said it was fine. I went ahead and swapped the Duralast Gold Top with a Optima Yellow top. Problem went about for about a month and showed up again. So I had the battery and Alternator tested. Both tested good but battery had a low charge. I went through the wiring and found a ground wire that had some corrosion on it. I cut the wire and reconnected. Everything seemed fine again for about a couple of weeks where I am seeing the issue come back.

The things I have done to try and correct this after reading some post on here.

Replaced plugs with Champion Copper .040gap
Replaced the IAC
Replaced the Tensioner pulley (bearings were going out)
Replaced belt
Cleaned Throttle Body
Filled the tank from almost completely empty (gas light was on saying 26miles til empty) with BP mid grade and added a bottle of Lucas Gas treatment. Did find it strange that I only got about 18.5 gallons in the truck
Checked in pitch dark and none of the plug wires are arcing. All wires are tied up safely with the plastic heat guards on all wires

 

500-600 rpms is normal idle for these trucks, that is fine, the flicker is most likely a bad ground(might take some hunting to find it) also make sure the terminals on the battery are clean, and the battery connections are nice and tight.

 

600 RPMs is fine for the 5.9L idle. If concerned, replace the IAC and the TPS.

Low power on the lights etc is probably a failing 12 year old alternator.

IndyD

 

I will check again for the ground issue to see if it is else where but I could only find 2 grounds so far. is there more than 2 grounds? there is one right at the front of the truck and other is on top of the engine. The terminals have the anti corrosion pads plus the spray. The cables dont move at all so nice and tight. If the idle is fine then how come its shaking like it wants to die? Other posters had said they are idling around 700 so I figured mine was low.

The IAC was replaced Saturday. The Alternator is only about a year or so old and tested fine from 2 different stores. AutoZone and Advance Auto.

 

Remember to pull and clean the grounding lugs off the motor block end. Clean all the grounding lugs not just the terminals (clean those too) and ensure a good, clean, and tight connection. If that doen't work replace the alternator.

500-600 is perfect RPM's

 

Has anyone replaced the alternator with a higher amp than the 117amp factory and had success with better charging? The reason I ask is because I have noticed for awhile now that if I turn on headlights, wipers and say heat. My battery drops to about 12volts until I accelerate again then the alternator will pull me back to 14volts.

 

136 is avail for your setup.

 

I tested tonight and found out if I run my factory fog lights with anything else, A/C or wipers or rear defrost my voltage will drop to 12 volts everytime. I am not sure if this is a failing alternator even though it test perfectly everytime or if its a normal operation of the durango. Does not seem like the best design but Dodge isnt known for best design on this machine. I have a concern with going to the 136amp alternator since it requires cutting the factory connector off and wiring manually, as well not sure if that small of a increase is worth spending the extra money if it wont fix this.

This thing has become a huge pain. I am hearing 500-600rpm is normal but the truck doesnt like running that low since the idle gets rough at those rpms. I am just not sure what to do with this thing anymore. Everytime I drive it I have to fix it.

 

136 should be OEM installed at the factory.


When is the last time you did a tune up and what parts did you use?

 

It has been about 3 years since a actual tune up. But I drive my car like once a week. In the 3 years I may have put 15k miles on it
I had originally swapped plugs and plug wies to Bosch. Cap and rotor are from Autozone so dont remember the brand. I put Champions in this past weekend.
Its running cold air intake K&N
Oil is changed every 4500 miles.