Throttle cable causing slip?

[LittleGiant]

4.0 Auto. Been slipping from 3 to 4. About 100-300 rpms. Had my TCM tested by @Wranglerfix. They were amazing and said when they put my TCM in their jeep it made it slip a bit. After installing new one from them I still have a slip. I’ve done everything they said to troubleshoot and it still slips.

Im told it could be the throttle cable being too tight or loose. Is that possible?

Here are a few pics. The cables are not factory and also do not have a way to adjust them.

Also, what’s the 3rd spot for? There’s another cable slot too with nothing in it.

 

[macleanflood]

No TV cable on that transmission...all controlled by the PCM/TCM.

I suppose your throttle position sensor could be reading faulty...

@hear is who needs to help answer these questions.

-Mac

 

[LittleGiant]

What’s the other cable? I know the one is the cruise control

 

[L J]

What’s the other cable? I know the one is the cruise control

 

[hear]

One is cruise, one is throttle, and the empty slot is I guess for the TV cable used on the 32RH. I'm a little surprised they used the same bracket on the later years, but not completely stunned.

 

[hear]

I don't know a ton about how the 42RLE does it's thing electronically, but ultimately the computer needs to know about the throttle input which comes from the TPS. How that would translate into slipping escapes me. It shouldn't be slipping regardless of the throttle input, so I'm wondering if you don't have an actual issue inside. ¯\_(ツ)_/¯

 

[LittleGiant]

I don't know a ton about how the 42RLE does it's thing electronically, but ultimately the computer needs to know about the throttle input which comes from the TPS. How that would translate into slipping escapes me. It shouldn't be slipping regardless of the throttle input, so I'm wondering if you don't have an actual issue inside. ¯\_(ツ)_/¯

An actual issue inside the tranny?

 

[hear]

An actual issue inside the tranny?

Yeah, slipping is generally either a pressure or a friction problem. Although the fact that putting your computer into a WranglerFix jeep cause theirs to slip too does negate my theory a little. I don't know how the computer could cause it to slip.

Maybe we need a better description of the slippage?

 

[LittleGiant]

It slips from 2-3 and sometimes from 3-4. If I take it really easy it doesn’t but if I really get on it, it’s slips bad. Minimum of a 100rpm jump up then back down to normal. Sometimes it jumps 500rpms. This is only when accelerating

 

[KennethS]

It slips from 2-3 and sometimes from 3-4. If I take it really easy it doesn’t but if I really get on it, it’s slips bad. Minimum of a 100rpm jump up then back down to normal. Sometimes it jumps 500rpms. This is only when accelerating

Are you meaning it over-revs during shifts between gears?

 

[mrblaine]

I'm a little surprised they used the same bracket on the later years, but not completely stunned.

They used the same one on manual trans, no reason to change what works.

 

[LittleGiant]

Are you meaning it over-revs during shifts between gears?

Yes, it over revs and then locks into gear once it settles back down

 

[LittleGiant]

It also mig hit be worth noting that when going up an incline the jeep is very sluggish.

 

[macleanflood]

I'd be reading live ODB data and watch the throttle position sensor and trying to determine if it's sending accurate position data to the PCM.

-Mac

 

[hear]

Yes, it over revs and then locks into gear once it settles back down

ok, so more of a flare then. That could be a delay in the clutches engaging. Why is a whole 'nother story.

This is why I don't want to own a 03+, I'm not skilled enough to troubleshoot computer stuff.

 

[LittleGiant]

Lovely lol. Well I hope the jeep can swim because I live by the ocean.

 

[LittleGiant]

ok, so more of a flare then. That could be a delay in the clutches engaging. Why is a whole 'nother story.

This is why I don't want to own a 03+, I'm not skilled enough to troubleshoot computer stuff.

What would be the fix if it was a delay in the clutches engaging?

 

[LittleGiant]

Update…

I replaced the TPS. I could have sworn I had already replaced that in the past but. Subs not. I keep a spreadsheet of everything that I fix, the cost, and where I got the part from. I checked my spreadsheet and it wasn’t on there.

As of now, there is no slipping. But couch that be a temporary fix because I completely unhooked the battery?

 

[LittleGiant]

Updating the update…

Well it fixed the slip from 2-3 but not 3-4. How is that even possible?

 

[hear]

Updating the update…

Well it fixed the slip from 2-3 but not 3-4. How is that even possible?

At the risk of drastically oversimplifying how it all works..... The computer takes some inputs and tells certain solenoids to fire/un-fire. Those solenoids control fluid presssure to make certain clutch packs apply/un-apply

If it's slipping, that means that the clutches aren't able to apply enough friction to give you the gear in question. That could be because the frictions aren't frictiony (technical term) enough. Or it could be because there isn't enough pressure to push the clutches together. Or there would be enough pressure but something is bleeding off that pressure.

If it's flaring, that often means that there is a delay in applying/un-applying the pieces that take you from 3 to 4 in your case. Imagine you had a manual and you hit the gas hard while the clutch is still pressed, you'll flare the RPMs. So maybe a solenoid is slow to do it's thing, or maybe the computer is slow to tell it to do it's thing. Or maybe one clutch pack is slow to bleed off the pressure, or slow to have pressure applied.

But honestly I don't have a 42RLE so I'm just kinda going off how things work in general. The computer & solenoids make it extra hard for a novice like me to troubleshoot. On the other hand, it's probably why every transmission shop in the world will immediately just tell you that you need a rebuild — troubleshooting is hard and rebuilding is profitable.