'98 Dodge Dakota RPM fluctuations


#1

I have a 1998 Dodge Dakota with the small v8 (318ci, I think). The trouble I’m experiencing is while driving on the freeway, doing approx. 70mph (2200rpm); every few minutes the rpm’s jump to 2400-2500, without any extra pressure on the pedal. It lasts for a good five seconds, on and off for about 30-45 minutes on a long drive…then just disappears.



Ive taken my truck to the Puente Hills Dodge dealer, and they used their OBDII scanner and claimed to have road tested the vehicle, but were unable to reproduce the problem. The problem with their findings is that the mileage was the same from when I dropped it off, and when I picked it up.



I’ve had my truck for 9 years, and it only has 81,xxxmi. on it; and I was wondering whether this situation could benefit from a major tune up. My last tune up was about 25k miles ago (approx. 3 years ago). Do you think it’s time for a tune up.


#2

Automatic or manual? why are you saying the RPM’s increase? Do you see the tac change or do you feel it or do you hear it or all three?

As far as maintenance, I am not sure it could be a cause, but if you are behind what the owner’s manual states as recommended maintenance, then you should start there. Putting that off often cost you many times more than getting the maintenance done. Even if you don’t notice it, just a small increase in mileage can pay for the cost of the maintenance.


#3

Joseph,
thanks for the response. The truck is an automatic, and yes; I do hear and see all three when it happens. I don’t drive the truck much, as you can tell (25k mi. in 3 years) and I do keep it properly maintained (oil/fluid changes, belts, etc.). My last major service was just before the 60k mile mark.


#4

Sounds like the torque converter is unlocking and then locking again, which will make the rpm’s increase and decrease a bit each time. Has the transmission fluid ever been changed?


#5

I think the torque converter is unlocking and locking up again. This is normal if you are going uphill. Dodge is bad about shifting down to 3rd when this happens resulting in quite an increase of RPMs until it shifts back up to 4th and then locks uo again.