Transmission gear search: PCM or something else?

catbones2010

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Sep 14, 2022
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Hey guys!

So my 2006 Jeep Wrangler for a couple months from time to time will have this weird issue where if I leave the O/D on with 33" itll do fine but at some point will feel like it revs up, then down, up then down.. like its looking for the right gear to pop into. I know I should have O/D off probably with 33" but its on flat grounds not hills so I don't think it should matter much. Now, turning O/D at that point is not fixing the issue. It'll still do it, I can see the RPM fall from 2500 to 2000, then up, and down... etc..

Would this be related to the famous PCM issues 2006 TJ/LJs have or is the PCM issue hard shifts only. No check engine light either. Maybe not the PCM but spark plugs, fuel injectors? not enough poof to move it into the right gear between those rpms?

Now just out loud thinking; I swapped my oil pump assembly and used the aftermarket sensor on it, because the OEM just fell apart trying to take it out from corossion, would that be related or has the OPA have nothing to do with it?

As always, thanks in advance for your thoughts, comments and suggestions.
 
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I just played with some numbers on Grimmjeeper, and going from OD to 3rd should result in a > 500 RPM change, I'm wondering if it's the torque converter lockup? On the other hand 500RPM reduction from the lockup seems high, but I've also never driven a 42RLE.
 
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I just played with some numbers on Grimmjeeper, and going from OD to 3rd should result in a > 500 RPM change, I'm wondering if it's the torque converter lockup? On the other hand 500RPM reduction from the lockup seems high, but I've also never driven a 42RLE.

I can't see TQ going bad after 50k, maybe a sensor or something clogged not putting enough fluid pressure. I'll check the level :) I also don't think I should be doing maintance on 50k trans lol but shit happens.
 
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I can't see TQ going bad after 50k, maybe a sensor or something clogged not putting enough fluid pressure. I'll check the level :) I also don't think I should be doing maintance on 50k trans lol but shit happens.

If it is a sensor going bad the PCM/TCM will tell you but it may take a few cycles before you see a CEL and a code, this includes a bad or slipping TC on lockup.

Not only mileage but age is also the enemy of transmissions.
 
If it is a sensor going bad the PCM/TCM will tell you but it may take a few cycles before you see a CEL and a code, this includes a bad or slipping TC on lockup.

Not only mileage but age is also the enemy of transmissions.

unless a fuel injector/spark plug is misfiring right at that moment... skips, so the engine chokes a little and drops the shift. I donno, guess we will see in the next few bit of time here if any codes come up. I might do the simple stuff and replace these original factory spark plugs.
 
unless a fuel injector/spark plug is misfiring right at that moment... skips, so the engine chokes a little and drops the shift. I donno, guess we will see in the next few bit of time here if any codes come up. I might do the simple stuff and replace these original factory spark plugs.

I would advise that you don't start throwing parts after the problem, the PCM will throw a code if there is a misfire.

The PCM and the FSM are your best resource to resolve your problem, let the PCM do its job and when it finds the problem use the FSM for advise and a fix. You will find the FSM in the Resource tab for the forum.
 
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If it's been doing this for months and hasn't thrown a code yet, I don't know that I would wait any longer. But I agree about not just throwing parts at it. Does the 42RLE have a separate plug for the TC lockup? If so, I would unplug it and see if it changes the behavior any.