Shifting worse after changing transmission fluid and filter

Tiny
M1KEB
  • MEMBER
  • 2002 JEEP GRAND CHEROKEE
  • 4.0L
  • V6
  • 4WD
  • AUTOMATIC
  • 160,000 MILES
The car was hesitating shifting gears. Once it shifted it would remain in the gear and downshifting was fine. I changed the fluid, added Lucas Transfix, actuator spring was broken in two. I replaced actuator spring, put new governor pressure solenoid and new sensor solenoid, new filter, added ATF+4 fluid. Now it shifts up normally but then drops back to lower gear. It cycles 1 to 2 and 2 to 1 and 1 to 2 etc. If I accelerate it will shift to 3 and then slip to neutral. My thoughts are one of the replacement parts is bad. Any help is greatly appreciated.

The vehicle listed above is a Laredo 4L 42RE transmission.

Sunday, February 6th, 2022 AT 11:33 AM

13 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,640 POSTS
Hi,

Have you checked for diagnostic trouble codes? Also, were you able to find all the pieces from the broken retainer?

Let me know. What you are describing could be the result of a few things.

Joe
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Sunday, February 6th, 2022 AT 8:43 PM
Tiny
M1KEB
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Hi Joe,

It was not a retainer but the actuator spring which is inside the piston. I removed the two parts of the spring. And I use a blue driver code reader. There were no codes either before or after I serviced the transmission.
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Sunday, February 6th, 2022 AT 11:54 PM
Tiny
JACOBANDNICKOLAS
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Hi,

The idea that there are no codes is leading me to think there could be possible line pressure issues or an issue with the valve body itself. The idea that you replaced the pressure sensor should help the testing show normal. If I had to guess if one of the parts you purchased was bad, I would think the pressure solenoid would be first on my list.

Do me a favor. Take a look at the pics below. They provide directions for testing line pressure. It will require a pressure gauge but really isn't that hard to do. See if it is something you feel comfortable doing and let me know.

Let me know.

Joe

See pics below.
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Monday, February 7th, 2022 AT 6:00 PM
Tiny
M1KEB
  • MEMBER
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Hi Joe, I am working on this in my drive. I jack the front of the car up and put on jacks to drop the transmission pan. So, while those test procedures do not look difficult, I do not have a helper and I have no way of getting the rear axle off the ground. It does seem like the problem is pressure related and since it was shifting late but holding gears before I would assume it's like you said the solenoid or the sensor. Another thing I wondered about was an electrical issue, maybe one of the wires that plugs to either of these is bad. Another post someone said they put the old filter back on and it worked fine. That is a bit hard to understand but I was thinking of pulling the filter off and not using a filter just to test, putting the old solenoid and sensor back on and see what if anything changes. If nothing else, I can eliminate those two items. If it's the valve body I was thinking of putting in a Transgo shift kit. Can I test the pressure with the car stationary with a long hose on the vacuum gauges and me sitting with my foot on the brake putting it in drive etc.
Thank you for your guidance on this.
Regards,
Mike
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Monday, February 7th, 2022 AT 7:49 PM
Tiny
JACOBANDNICKOLAS
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Mike,

You can test it yourself with a long enough gauge. Basically, you need to determine line pressures at idle, in gear, and so on.

As far as no filter, nope, don't do it. It will pull anything into the VB if it's there. A new filter isn't causing the issue.

The idea of a wiring issue can certainly be a problem. If you have one that is not making good contact, it could be causing the erratic shift. When you had it apart, did you inspect connections and wiring?

Let me know. Also, let me know if this is the original transmission.

Take care,

Joe
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Tuesday, February 8th, 2022 AT 2:26 PM
Tiny
M1KEB
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Hi Joe,

The transmission is the original. It sounds quiet, there were not any metal particles in the pan or around the magnet. When I changed the fluid, it was a bit dirty, not unusual for it at the end of cycle before changing. It was not burnt or muddy or anything like that. It shifts smoothly and sounds quiet. I put the old pressure solenoid and sensor back in. I never got a chance to test it yet, it's still up on jack stands. I will need to pick up an oil pressure gauge. I'll let you know more tomorrow. As far as the wires I did look at them and there was no obvious damage. I was thinking there was good pressure when I drained the old fluid. I removed the hose on the return line and flushed the old fluid out as I filled it with new fluid. I think that demonstrates the pump is working okay. I will let you know tomorrow if it is any better. Thank you
Regards,
Mike
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Tuesday, February 8th, 2022 AT 9:28 PM
Tiny
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Hi,

Thanks for the update, Mike. I look forward to hearing the results.

Take care,

Joe
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Wednesday, February 9th, 2022 AT 2:59 PM
Tiny
M1KEB
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Joe,

Thanks again for your help with this. I installed a new filter based on your advice, I know it's hard to believe the filter was involved but I wanted to eliminate everything new and your recommendation not to run without a filter was good advice. I put the old solenoid and sensor back in. I adjusted the band inside the pan, installed a new output speed sensor and when I test drove it, I was back to the problem I originally started with. It does not shift into second gear until 40 MPH. Sometimes when I let my foot off the gas it will shift slightly faster but not all the time. I am guessing that has something to do with releasing tension on the throttle valve cable. I don't completely understand how this is all working. I ordered a Mopar set of solenoid and sensor that should arrive next week. Until then I will not be doing anything with it. I am hoping that is all it is. I will let you know. Even shifting at 40 MPH it is pretty smooth. I do not intend to drive it until the new parts come. Thank you again.
Regards,
Mike
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Wednesday, February 9th, 2022 AT 8:40 PM
Tiny
JACOBANDNICKOLAS
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Hi,

The solenoid valve generates the governor pressure needed for upshifts and downshifts. I suspect that is the cause. If possible, let me know if the replacement eliminates the issues. I'm interested in knowing.

Take care,

Joe
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Thursday, February 10th, 2022 AT 4:13 PM
Tiny
M1KEB
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Hi Joe,

Thanks for the explanation on the solenoid. What is the function of the sensor? I will let you know what happens when I receive and install the new parts.
Regards,
Mike
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Thursday, February 10th, 2022 AT 7:00 PM
Tiny
JACOBANDNICKOLAS
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Mike,

The governor pressure sensor measures the output pressure of the governor pressure solenoid valve. LOL, It's like one big loop. Regardless, the pressure sensor output signal provides the necessary feedback to the PCM to accurately control pressure.

I hope in some way, shape, or form that makes sense.

Take care of yourself,

Joe
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Thursday, February 10th, 2022 AT 7:50 PM
Tiny
M1KEB
  • MEMBER
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Hi Joe,

The new solenoid and sensor took care of the problem. It is shifting fine now.
Thank you for all of the help.
Regards,
Mike
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Saturday, February 19th, 2022 AT 5:03 PM
Tiny
JACOBANDNICKOLAS
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Mike,

Thanks for the update. I'm glad to know you are up and running again.

Take care of yourself, and feel free to come back anytime in the future. You're always welcome here.

Joe
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Saturday, February 19th, 2022 AT 7:53 PM

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