I'm new here so bear with me on this. I am a little mechanical incline so if you name parts or tell me whereto look I will look in my book (Chilton's) or on the net and if I have questions I will ask.
OK......
We have a 1998 Durango 5.2L4x4 auto. The RPM's are jumping up starting around 1600-2100 and will only jump 100-300. The speed with OD on is around 43-60/70. I tested it to see if it would do it with the OD off, at 1600-2100, and it did butonly a few times. We first started to notice this with the cruse control on. We stopped using it and it did not do it until a while ago. At first I thought it had something to do with the cruse control so I just said OK we will not use it until I get around to looking at it. No biggie so I thought (that was my first problem, right "I thought" LOL). There is no speed increase or decrease but the engine does rev. It only happens for 1 sec or less. It happens on smooth, bumpy, up/down hill. It does not happen when first taking off but when at a light/stop the RPM's jump up around 100-300 sometimes. It has been doing this for a while now but the strange thing about this is it is doing it on and off for the past week or so. I'm getting ready to check the vacuum to see if I have a leak, if that has anything to do with it. I checked two plugs on the trans and there was no moister or corrosion. Is there a plug coming from the Powertrain Control Module? How many plugs are on the outside of the trans so I can check them? Could it be a torque converter? (please no no no) Oh, I did check the trans fluid and it looked good, red, and smelled good, not burned. I was going to get a code reader to see if it had a code. No, the check engine light is not on but would I still get a code? I would think not but that could be me thinking again LOL. If I forgot something or anyonehas any questions you can email, IM, or just post. I will leave my I'M program up and running if that is how you want to contact me. My email is foghornbill at yahoo dot com and I have IM accounts with Yahoo, MSN, AIM(AOL). My name at Yahoo and AIM is foghornbill and MSN is the email. If you have problems with AIM one try the email address. I check my email a lot during the whole day and I will check this form a few time a day also, just in case I do not get an auto email.
Thanks for any help from anyone and once again if you have question for me let me know and I will get back with you ASAP.
Bill

 

are the rpm's jumping while your foot is on the gas. does it fell like someone just put your car into neutral while you were diving and than right back into gear?

 

yes my foot can be on the gas, as in trying to keep a constant speed,but it does not feel like it goes out of gear. there is no jerking just the engine rev's up then back to normal. is that what you are asking? but when i accelerate it does not do it, if that is what you mean.

 

HI there,
It sounds like the same problem we had with our 2003 durango.

It turns out that it was the TPS(Throttle Position Sensor) once that was replaced the problem went away. How long has this been going on? Also when you are in park and just Idling do the rpm's about the same thing?

 

You might want to take a peak into getting the transmission serviced (Fluid/belt adjustment) just out of spite. As for the tps/etc etc, since you have a book, before jumping into a purchase i'd recomend breaking out a multimeter and testing the sensors/connectors first.

 

chillininnd-----
i would have to say that it has been going on for about a month and a half, maybe just over. but within the past week or so it has been doing it on/off. yes it will do the same thing when i am in park, like when i first start up and after it has been running for a while. it will rev up then back to normal several times. it mostly happens when there is a constant rmp between 1600-2100, but it will happen when at that park/stop idle.
Duranged408-----
i'll look at the connections and test the sensor. are you talking about the "band" in the trans? if so, then i'll take a look into that. i'll do a trans fuild/filter change around next fri or that weekend. the trans fulid looks and smells good. i know that it would have nothing to do with the band in the trans. i'll give a dealer a call to see what the torque range should be on the band. i'll call them to see if it matches up with the chilton's. how long would it take to replace the band, if i went there, and is it a hard job or is it like just changing a belt under the hood?

 

FoghornBill,

I am confident it is the TPS that is bad. I went thru the same headaches as you did and the Dealer even had my D in the shop for up to 2 weeks trying to figure this out. I mean, they had all kinds of high tech gear connected to my D to monitor the PCM and try to get the errors when it does this. But it does not. So I took the lunge and got the dealer to replace my TPS on recommendations from users on this site a couple years back and the dealer says if they do this, it will not be a covered under my 3/36 warranty. I told them to replace it anyways and I paid for the $34.xx part and voila!, no more rpm surging and wobbling. Dealer was suprised too. So they waived the cost. Damn, I love that dealer [(they aren't around anymore! ].

What came down to, is the TPS was just slightly out of range just enough to make the surge but not enough to register an error code for the PCM to make a log. I am just glad to have my D back after being in the shop for over two weeks and a full tank of gas wasted trying to figure this out.

 

Kensai-----
ok. i might just take the plunge then and get it. if that does not work i will let you guys know. i'll still check it with a meter and see what the volts say. per chilton's "engine --off -ignition --on, volts between 0.2 - 1.4, move throttle pulley to wot (wide open throttle) then volts should rise slowly to less that 4.5". then it goes further to check power/ground and so on. did they test the volt range in yours before replacing it? just asking on that one. also do you know there, chition's, definition of "the voltage should slowly rise to slightly less than 4.5v at wot." as into what should be slow? like i watch the volts increase as my hand moves it or a delay or i go wot then they increase. thanks again for all the help.

 

That test usually does not work. It will get you by tho.

I would say the the TPS is bad. While you are looking at the throttle body pull the IAS sensor and clean it and also the throttle body. Look inside the manifold through the throttle body and see if you see oil. If so the Plenun gasket on the bottom of the intake manfold might need to be replaced.

It could also be the torque convertor becomming unlocked. It does do this as a fuel saving feature. In this case I would get the trans bands adjusted and fluid/filter change.

First I would do a TPS change.

 

Yes, the dealer check the TPS and came out okay. The sensor tests out okay but as stated in previous post, I think when the TPS is in part throttle (cruising), its that area where it gets crazy. I think the electrical dial inside has a bad spot or excessive wear right at that throttle setting where it messes up.

To date: Since I have replaced my TPS, I have yet to see my surging issues return. Been a over a couple years and still running ok.

If the TPS does not solve your problem, then continue on troubleshooting with Hydra's recommendations to clean the IAS sensor and check for plenum gasket leaks, etc.

Most common sensor outage issues I have seen reported from our forum usersare:

TPS sensor
Speed sensor
Output sensor

The speed sensor and output sensors are located at the rear of the tranny itself and on top of the rear axle. It is best to replace both sensors if one of the two goes out as both sensors work together. These two sensors affect how your tranny shifts, speedo flucunating, and ABS errors.