ok so im new on here so please bear with me. I have a 98 dakota 3.9ltr auto 2wd. its my winter beater/ dd and i love the thing. lately ive been having a problem with it at starting and stopping. i recently was forced to replace the gasket on the trans. and while i was in there did the filter. problem is the person before me didnt ever service it and it has 180k on it. i know the rule of thumb is after 100k+ dont touch it, but i didnt have a choice. lately when i start or stop at a light ( >5mph), the whole truck shudders like it has a broken mount. i went through everything, and nothing is broken. bext i checked all the fluid levels, still nothing wrong. i checked to see if the brakes are hanging up, and nothing again. when i turn left, it has a lil hop like a bad diff, but everything seems fine inside when we checked it, no missing pinion teeth and axels seemed like they were in good shape. its progessively getting worse, and the winteris to cold and snowy and ****ty for my show truck. does anyone have any advice on what it could be?

 

That sounds a lot more like a problem with the Idle Air Control, not the transmission. I'm not sure if an IAC problem will set a trouble code from the PCM. You could ask at a parts place and see if they will read the codes for you. Some won't do it unless the check engine light is on. If the IAC is bad you can remove it and very gently clean the black crusty crud off the pintle end. It's a good idea to rempve the throttle body and clean the orifice for the IAC too and be sure not to lose the O-ring for it. Reinstall the throttlebody with a new gasket. When the IAC gets dirty the truck will have a rough idle, it won't idle down properly and will sometimes even stall out when slowing down. If the IAC has never been cleaned or replaced, it may just need to be replaced anyway. They don't cost much, I think about 30 bucks here in Florida anyway. Don't drop it or handle it roughly or you will need a new one regardless. It's a good idea to clean it at every tune up, and clean the throttle body and lube all the linkage and pivot points too. I do mine every 20,000 miles. The IAC is located on the back side of the throttle body. It is held in with two T25 torx fasteners.

You might also check the TV cable adjustment. I don't know much about them, my Dakota is a 5-speed manual. Search here or Google Dakota TV cable adjustment. I think those have to do with how the truck behaves when stopping or slowing down. A Haynes book may have info on it too.

Hope that helps. Good luck, and let us know what happens. And Welcome to the forum.

Jimmy

 

it wont flip a code. just clean it with carb cleaner as well as your TB.

 

its not that the idle is low, its idle is very high. i know there is a major vacuum leak and it idles in park at 2200 rpms, but in drive and reverse its 1100 rpms. it almost feels that the driveshaft is shaking. i had a ford before and the universals kept blowing out, with a little help from me. but it seems like the same shudder as that, but the bearings seem to be in order and sound. let me kno and i will check the codes and post them as well. i just love the truck and dont wanna see it go down in flames.

 

Sounds like what is commonly known in the auto transmission world as Torque converter shudder. Verry common in R.W.D. autos and pretty much all cadilacs. My first suggestion would be to scrap the auto and swap in a manual trans. 2nd sugg is to try swaping the Tq Converter. 3rd would be building the trans. I COULD BE WRONG. I am by no means an auto trans expert but I have had enough dealings with them and spent enough time with People who know then inside and out to know that I will always do everything possible to never own another one.

 

Idling that high in park or in gear, there has to be something seriously wrong somewhere. I would find and fix the vacuum leak pronto, and check your IAC. IAC problems are kind of a common thing on 3.9's.

 

I agree with getting the tune in order and then see where you are. My older son's Dodge Dynasty suffers from the dreaded converter shudder. When the car is cold and sometimes when it is warmed up even, the converter does not "unlock" when slowing to a stop and it will shudder and stall the engine. His problem was magnified because the egr valve needed cleaned badly and once this was taken care of it is not nearly as prone to stalling when this happens. I think the idle air control valve does about the same thing as an egr valve so cleaning it is in order along with a new pcv valve and finding any vacuum leaks or other tuning issues. There is a definite difference between a stumble and a shudder and you know quickly the difference when you experience it enough.