I have a 2002 Dodge Durango that is having an issue with the RPMs fluctuating when driving and sitting still just idling. Not only do the RPMs jump up and down by 300 to 500 rpms but the engine also fluctuates with the rpm changes. The speed doesn’t really change but the engine sounds as if it does. At first you really don’t notice it that much. It happens every so often and only by 200 to 400 rpms. As a few days go by the issues gets a lot worse. It starts fluctuating a lot and all the time by 400 to 500 rpms and at that time you can really feel and hear it in the engine. By this time the vehicle will speed up and slow down according to the amount of RPMs change and at this point it will make much bigger jumps in the amount and a lot more often. Pretty soon the RPMs aren’t the only thing that is jumping around; the passengers are now able to feel it and are also being moved forward and backward when the fluctuations start. When the issue started the check engine light was not and did not come on, but over a few days time, the light did come on and stayed on.
I’ve also noticed the transmission acting funny too. When I slow down to make turn and after you are in the turn and give it some gas to go on, it shifts really hard. I have noticed that if you don’t give it any gas but let it slow down more after the turn that you can give it some gas and it will shift just fine. I’m really the only one that drives it so I just pay attention while going into turns and I just don’t give it any gas until I can feel that it has slowed enough for it to shift right. It has gotten to where I can feel that just right point before giving it any gas and that is how I have been driving it so that there isn’t any damage done that I can’t afford to repair because I know that a transmission shouldn’t shift that hard for just making a turn. Actually I can’t think of any reason why a transmission should shift that hard at all.
If anybody has any ideas as to what to check or repair I’d be so grateful for your help. Thanks

 

Mine just started rpm fluctuations yesterday exactly as you described. Check engine light came on delayed just like yours too. I've not noticed any hard shifting in turns yet but we'll see what happens.

If I find out anything I'll let you know. Please keep me in the loop as well!

Mike
941-961-3579

 

Hi guys my 2000 dodge durango 5.9 RT has been doing much of the same stuff ive been to shops ive replaced alot of parts but no change i was wondering what engine code you got the one i got is p0505 and meand idle air control system.

 

https://dodgeforum.com/forum/dodge-d...s-section.html

i would start by changing your IAC motor and resetting the PCM(based on the Idle air control code) and if that doesnt do it change the TPS

 

Could be the throttle position sensor. Had this issue on mine. It's about $35 bucks, takes 2 mins to fix.

 

Ya i have replaced the IAC, TPS, MAP sensor, cam positioning sensor. I did a complete tune up new wires spark plugs. Whats happening is while im driving down the freeway and let off the gas the RPMs will go up about 500 and stay for about a second then suddenly drop to where they should be then go up again back and forth all by its self. Let me also say this does'nt happen all the time maybe once or twice a week. Then the other thing its doing is when i start it it will just die unless i give it alot of gas to keep it running then when it heats up it will keep its idle. Feels like the IAC motor isnt working all the time. Sorry one more thing and this seems to happen alot and that is my RPMs will stay real high like 3000 or so even if i take my foot off the gas and trying to stop is a pain. but once stopped the RPMs will slowly come down after a min or two. Im not sure what else to do i usually can figure stuff out but this has got me. What really sucks is DEQ is in a couple of months ahhhh. PLEASE HELP!

 

replace your IAC motor as this controls idle speed and will most likely fix the starting issue, the rpm fluctuations is most likely the TPS so replace them both and reset the PCM and get back to us

 

This is probably completely unrelated - but I figure I'll throw it out there anyways...

My 2000 5.9 has a very slight RPM jump, but ONLY while using cruise control.

At approximately 65MPH, my enging is turning a lovely 2000rpm... But when I set cruise control... The RPM's will sporadically jump up to 2100rpm and then back down to 2000rpm. This happens every few minutes.

It has done it ever since I've owned the truck (about 3-4 months now) and it's more just quirky than anything else.

It hasn't gotten any worse, and I don't use cruise control all that often, but I will be going on a long road trip in about 6 weeks and I'll probably want to use cruise a fair bit.

I can just feel the engine jumping that 100rpm and then backing off, and jumping, then backing off... At first I thought maybe it was just fighting some wind resistance or something... but that doesn't seem to be the case.

 

rob - thats the first sign of a TPS going bad

replace the tps and reset the pcm and i bet it goes away

 

Awesome. Thanks... I'll try to get it done next weekend.