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Slight Pulsing Feeling

5K views 13 replies 5 participants last post by  Madanio24 
#1 · (Edited)
06 Laredo 3.7L AWD

When just driving around which is up and down a lot. If you are in OD and start to go up a grade, sometimes you can feel a very light, but noticable, pulse (like a really quick downshift/upshift, repeatedly).. not violent, but its almost like the TCM can't decide to downshift to get up the hill, or to stay in OD.

Any idea why and how to fix this?

Truck has 88k and goes in for trans fluid change next week. Both diffs were done a few weeks ago.


Dont want to make multiple threads...

The other issue, when its REALLY hot out and you've been driving for awhile and come to a stop. IF you let the Jeep idle for a few minutes, it will randomly and not consistantly idle down and jerk and then idle back up where its suppose to. it will drop down to 600 or so RPM's, shake for a second and go back to normal. I dont think its stalled on her yet.

Plugs were just done about 5k ago, give or take.
 
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#4 ·
no real solution.. just the thread about it being common..

since we didn't buy this new, IDK if its osmething that's just going to happen due to the 3.7 being under powered.. or if there actually IS something wrong.

If guys are taking it to the dealerships and they are saying there is nothing coming up as being wrong with it. Even when they test drive it. What can we really say?

We got an aftermarket warranty that covers the drivetrain. I just dont think they are going to replace the torque converter or the trans because we think its the problem.
 
#6 ·
Mine doesn't do anything like mentioned in the thread (harsh jerking while driving down the highway).. Mine is more going from flat road to an incline and giving it gas while in OD but not enough to kick it down.. it seems to not know if it should kick down or stay in OD. its a light flutter so to speak
 
#7 ·
That is one of the symptoms of mine. I hardly doubt the answer is that the cars underpowered. After all it never used to happen before. The dealership actually felt my problem and are investigating further. He thinks it's a problem with the clutch in the torque converter not opening correctly.
 
#10 ·
Yep I replaced the Tps with oem one. The tech said the transfer case is locking up and opening he told me to throw in oem spark plugs and bring it back to him and he's going to look at it for a few days. Will post back because this seems like a fairly common problem. The only thing that helped a little bit was the update on the PCM definitely shifts a lot better :thumbsup:
 
#11 ·
The tech diffinatley felt the pulsing driving on his own in the car and doesn't think it's normal at all. Also asked him to use star scan tool to set my headlights to export mode! Super excited lol.
 
#12 ·
I also have this problem with our '05 3.7 Rocky Mtn edition.
I changed the TPS and now it's throwing a "P0122" code (low voltage to TPS).
I've been running E3 spark plugs and changed wires about 15k miles ago.
I can hear & feel a grinding when it hesitates. It makes me think that there is slippage in the trans. because I smelled the trans fluid and it has a burnt smell (witnessed by mechanic friend also).
Also had trans & converter flushed about 1 year ago.
I have made a contact with a Chrysler tech and he is going to look at it within the next couple weeks....hopefully all my troubleshooting will have put this in a repairable direction.
 
#13 ·
the jeep dealership put over 10 hours trying to diagnose the problem. They were amazed that they couldn't figure out what it was. They tore into the engine, trans and tc checked every sensor and still everything is functioning as normal. They also collected numerous flight data which was sent to chrylser themselves and everything is normal. The jeep dealership gave up and said I'm just going to have to way until something actually breaks.
 
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