Hello all,

I am looking for some help tracking down issues with my 2002 Dodge Durango 4x4 with a 4.7L engine. I now has 162,000 miles on it and up till now all it has ever needed was regular maintenance. Now Randomly I will slow down for a red light and the idle will wave between 400-800 rpm sometimes completely turning off the engine. I can restart the engine with no problem. The engine seems to run perfectly except for occasionally when slowing down the idle goes crazy and may stall. I have installed a new IAC, gas cap, checked the vaccumm lines with a propane torch, seafoam, reset the computer for a couple hours. No codes from the computer. Nothing seems to change the situation. The only other information I can add is that if I shift the transmission into neutral and back to drive when it starts having issues it stops. The only idea I have left to try is flushing my transmission to see if it is not downshifting properly. Any other ideas what may be causing it?

 

Try cleaning the battery terminals.

 

+1 on the battery, But i would recommend to clean the throttle body and the ilde speed motor.

 

Also try to wiggle the Throttle Position Sensor connector with engine running. Sometimes a bad TPS cause die out and rough idle.

 

did you check ALL vacuum lines? i would say check your pcv hoses ,the inside flow (on the back of the valves cover, both sides) , and the hose on the oil fill cap, it goes to the back of the throttle body, check too the hoses of the EVAP, if those are broken or have leaks , you will get bad idle, if you dismounted your thottle body, did you change gasket and torque it to specs? if you have leaks there , it could cause that symptoms, check oil pressure too when you stop , if pressure goes down ,problem could be there

 

Two summers ago I had an issue something simular to your problem, My engine died out when I was ridein down the road at 50 mph ,drifted to a stop and started right back up, it did throw a code and it ended up being a camshaft position sensor, installed new one never did it again. just a suggestion for ya. good luck

 

Well so far I checked the battery terminals. They seem to be fine and voltages for battery with engine off and with engine on seem in proper range. I cleaned the throttle body again. I also double checked connections.

And then on the when I turned my truck on this morning it finally decided to give me a code. P0440 Evap system. So Vaccum lines might be a very possible cause. I have checked all the lines in the engine bay. Tonight hopefully I will check the lines running back to the canister and Tank and report back. Thanks for all the help.

 

Ok.. So I finally got around to doing some more work on my truck. I did find that the negative terminal on my battery moves inside the battery itself. I replaced the battery. I checked all the evap lines and put hose clamps along all of them. I flushed my transmission and did an oil change. I put a new OEM gas cap on the truck. The rough idle went away and it no longer wants to stall. It is actually running really well minus the P0440 code which comes on every time I get gas. Any ideas on how to fix that problem. The only Idea I had was maybe the pump for the evap system is not pressurizing the system properly. I do have a 25Gal gas tank which I think is larger than the normal.