2001 Dodge Dakota RPM fluctuations

Tiny
NEBUCHADNEZZAR
  • MEMBER
  • 2001 DODGE DAKOTA
  • V8
  • 2WD
  • AUTOMATIC
  • 136,000 MILES
What is the deal with my dakota when the rpms fluctuate while trying to accelerate? I have replaced all sensors reguarding the problem and the problem persists. Idle is fine, but once accelerating down the road, the rpms jump up and down. A steady pace on the accelerator at any speed (35-45-70) results in this "hopping" movement.
Sunday, March 14th, 2010 AT 9:33 PM

11 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Could the trans be slipping? Also, have you checked for vacuum leaks?
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Sunday, March 14th, 2010 AT 11:35 PM
Tiny
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Trans. Possibly. But it doesnt do it during the changing of gears. Just whenever it wants. Vacuum leaks. None. My father and I sprayed butane over every line 3 different times to listen for the burning of it through the engine. None. We noted the sound of it after spraying it through the K&N intake.
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Friday, March 19th, 2010 AT 9:42 PM
Tiny
JACOBANDNICKOLAS
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COuld you let me know what sensors you have replaced? Also, I starting to think it may be something with the trans. If the rpm's are jumping and you feel a hopping, it almost sounds like it is slipping.

Let me know.
Joe
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Saturday, March 20th, 2010 AT 11:55 AM
Tiny
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Literally almost all sensors have been replaced in the past 3 weeks. The TPS, the sensor below the TPS, The MAP sensor, all O2 sensors (4), I do not have a mass air flow sensor. There is a sensor below the MAP sensor that I do not know what it reads. Cam sensor maybe? I pulled the codes recently and it said "the system is too lean". Does that mean the air/fuel mixture is off? Also. This whole thing didnt start until I pulled a U-turn and tried to get up to speed in front of a few cars and my truck acted as if it was in neutral. The gas was going in and even though it didnt redline, the rpms went from 3000 to 5500 incessantly. It makes me lean more towards the trannie like you pointed out.
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Saturday, March 20th, 2010 AT 12:20 PM
Tiny
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  • MECHANIC
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You are correct about the lean mixture. It isn't getting enough fuel. Usually it is caused by a vacuum leak. However the trans has me concerned. Based on your description is sounds like it is slipping. Is the trans fluid full and clean?
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Sunday, March 21st, 2010 AT 1:37 AM
Tiny
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Transmission fluid is full. It hasnt been changed out since it was at 40000 miles or so. Now that im at 135000, do u think I should change it out? My father and I put some Lucas stuff in the trannie not too long ago. I am off to college and I had to take my moms jeep on the 3 hour drive away. I am relaying all the messages and advice that you give but my father swears up and down that he dont see how it could be the transmission. (He is big-headed sometimes) lol
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Thursday, March 25th, 2010 AT 5:02 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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He may be right. However, now we need to make the decision if the trans should be serviced or not. When you wait that long, many times when you put clean fluid into it, the detergent in the ATF will clean whatever is left to the clutch plates and make it worse. I hate to say it, but I think, because it wasn't serviced in nearly 100K, the clutches are out of it. Does it go into any gear?
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Thursday, March 25th, 2010 AT 10:11 PM
Tiny
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Oh yes. It is most assuredly driveable. Any speed you want to go, every gear changes. From first to second, it tries to JAM into second. All the others are way less noticable. Another point I wanted to add. With the hood raised, the truck in park, using the the throttle on top of the manifold, holding a steady force on the accelerator will still make the RPMs fluctuate. But only if you try to keep a steady force on it.
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Friday, March 26th, 2010 AT 5:22 PM
Tiny
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I agree with you. It sounds like an engine problem. THe hard shift may be a shift solenoid. As far as the other problem, something tells me it is either a throttle position sensor (TPS), idle air control valve (IAC), or a vacuum leak. WIthout the check engine light I have to guess. However, those are the parts I would start with.
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Saturday, March 27th, 2010 AT 8:15 PM
Tiny
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I appreciate it. I am going home tonight and I will try these things out and give you feedback on which one worked. Thanks for the help!
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Thursday, April 1st, 2010 AT 11:35 AM
Tiny
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Let me know. I will be checking my email everyday over Easter, so if you run into trouble or have additional questions, l'll be around. (NOTE: On Easter, it may be a little later in the day before I get back to you, but I will check.)
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Thursday, April 1st, 2010 AT 12:53 PM

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