Good morning all, I have a 2003 Durango with 103,000 mi. on it, 4.7L auto tran. rwd. I have a rough idle issue that I have seen better described as a stumbling idle issue. I don't want to rehash all the same stuff others have said, suffice it to say it's the same problem. I have taken notice though that the issue is not there when the a/c is on. When the a/c is not in use and I'm stopped at a traffic light the idles drops to about 500 rpm and the eng. is about to cut off, usually when the light turns green I can pull away without any stumbling or bogging, there are times the idle recovers by he time the light turns green, but far too often I'm sitting there waiting to see if the eng. will cutoff, it doesn't. Now here's the interesting thing I have noticed and I need to know if others can concur. I have noticed that when the weather is cool to cold starting around 55 deg. or so, the stumbling is not an issue. But when it gets warm to hot say around 70 deg. or hotter the stumbling is always there. This past late Dec. when VA. had a major snow storm I was there driving in it, temps were from the single digits to mid 20's and I never had a single stumbling issue. When I returned to my home in So. Fl. and the warmer temps. the stumbling started again. Can anyone think of any sensor that could react to temps. like that and cause the stumbling? I can rule out such things as spark plugs, air cleaner, fuel injectors, vac. leaks. mostly because none of those things would be temp. reactive. Does anyone else have thoughts on the matter?

 

Low idle stumble at start up is usually a bad battery. Check that first, then replace the TPS.

IndyD

 

Nope indy that's not it, as I said this happens when stopped at a light, and it clears up in cold weather and happens in warm weather. Clearly that is not a battery issue, as for the TPS if you can illustrtate how the outside temp could be impacting it I'm open to learning.

 

I had the same issue, check the Idle Air Control Valve, IACV right next to the TPS, may not need to be replaced but I took mine out, cleaned and replaced. I am not sure of the temperature relation but try that first. It took me about 30 minutes to remove, clean and replace.

 

Thanks for the info Magic, unfortunately I don't have time right now to do it. I will as soon as I can. Now when you say you cleaned and replaced it, are you saying you tried to clean it first and it didn't work or are you saying you cleaned the housing and replaced the IACV? By the way can you describe what it looks like, so I can be sure I'm workin on the right thing. Since you say you had the same issue can I take it that what you did indeed cleared it up? Thanks again.

 

I can understand the confusion, sorry about that.

I removed, cleaned and reinstalled the same one. At the time I checked the replacement it was about $100 so I just cleaned up the carbon out of the existing one and reinstalled. So far so good and this cleaning was in April. I might check it again at the end of this winter and clean out again. I am not sure what I cleaned it with but some sort of mild cleaner, possibly purple stuff or fuel injection cleaner should work. The key is to be careful around the o rings and check for dryrot.

I was not popping codes so I jut figured clean first and keep it simple.

The IACV on the 4.7 is under the TPS, I believe it is two or three torx screws and electrical connector.

 

i disagree only because the battery would be under more load int he cold than the warm and he says it doesnt happen in the cold


and it happening at idle is exactly why the battery IS a possibility, but not my first choice in this, in these trucks when the battery gets weak they dont run right, when you are on the throttle the alternator picks up the slack from a weak battery and you dont notice it, only at idle when it needs a little extra juice from the battery. (i guess if the computer raises the idle in the cold it could be enough to compensate over the warmer weather, but i would not rank it high on the list)

the TPS is another common cause of these problems, as is the IAC, the IAC can be cleaned with carb/intake cleaner just be careful not to move the plunger while cleaning it or it will not run right the first time you start it up after putting it back.

and the TPS is a very picky sensor if there is any condensation on it or in it it tends to cause problems, you didnt mention anything besides weather in your initial post, if it is warm and humid the seals on the TPS could be bad letting WATER VAPOR into the sensor causing problems, but the colder weather it doesnt get in since the water is in liquid form instead of vapor, a slim possibility, but still there.

and on another note, the IAC is also not a temperature dependent sensor in itself, the computer just opens it to raise the idle in the cold

 

Okay, lemme clear this up.. A low battery can cause stumbling at idle(stoplight/warm) yet start up perfect when cold. It may not be the same instance with other vehicles but it can/will happen with a durango...

Now, may it be bad/plates/ground/etc. i cannot elaborate since i have dealt with all issues with a battery replacement. When i was running on one remote system all issues were exaggerated being 20+ feet of lead.

Im not saying your issue is the battery, but dont rule it out.... To cross the battery off the list if this is a common occurance, reset your ecm to place all variables back to 0 and see if the issue is persistant.

 

OK sharpshooter, first thing, I replaced the battery some years ago, in fact I upgraded it to a higher amp batt. Even after a new bat. the problem was still there, I wasn't expecting it to go away with a new batt. By the way once the engine is warmed up the cold should not be a factor. The computer would register that the engine is at operating temp and not make corrections for the cold, it makes sense when you first start the eng. and it's cold, what you describe remindes me of the old heat riser valves they used to use to heat the engines quicker in cold weather, the one that used to rust and get stuck in the closed position, they were installed on the exhaust manifold, a real piece of junk it was. Anyway I can see your point of view that moisture is working it's way into it and fouling it. It does get hot and HUMID in so. fl. BUT I have read so many other posts on other forums from people in other areas that aren't heavy humid, so your idea may or may not have merit, doesn't hurt to check though. I'll probably checking this out on the weekend. That's why I'm gathering ideas now.

 

how many years old is the battery? the average car battery lasts about 4-5 years, its much closer to the 4 year mark on a truck with a large engine and lots of electrical accessories, so even if you replaced it, if it is more than 3 years old DO NOT RULE IT OUT!!!!!!!!!!!!!!!!!!!!!!!!