Just in case there are any guys with V6 dakotas out there that see this thread, only the 45RFE transmission in the V8 Dakotas have two filters. The 42RLE in V6 Dakotas has only the 'flat' internal filter and DOES NOT have an external spin-on filter. This was a source of some confusion for me when I was browsing the forums in preparation for a transmission service that I am planning to do soon.

Marc, when you switched over to the Royal Purple fluid, did you have a shop flash your TCM or do a quick learn reset? My guess is that Royal Purple fluid is like Amsoil or Redline ATF in the sense that its viscosity or frictional characteristics are significantly different (but hopefully better) than Mopar ATF+4. From my understanding of the situation, the TCM needs to be flashed or put in quick learn mode to adapt itself to the new fluid.

It's apparently a big enough issue that Amsoil issued a technical service bulletin on the issue that explicitly states disconnecting the battery terminals is not sufficient.

 

Is it just me, or does this sound like the torque converter isn't going into lock-up in overdrive?

Regarding the idle, might just be due for a good cleanout of the throttle body/idle air controller. Plugs and a new pcv valve couldn't hurt either.

 

I was never a mechanic but making the same highway drive every weekend for about 4 months, and then 2 years later after being in the army being able to do that again, that was my assumption. Only way to tell if im in Overdrive would be?

 

Checking whether or not the truck is in overdrive (5th gear on the 4.7L trans) is as simple as clicking the "Tow/Haul" button on the shift lever while at speed, and seeing if it shifts out of overdrive into 4th. Click it again and it should return to overdrive (5th).

But torque converter lock-up is one step past that, where the converter essentially locks the input and the output as one (as I understand it, bypassing fluid coupling), as how a standard clutch "locks" the engine output to the transmission input. It almost feels like another gear when it goes into lock-up while in overdrive, since it drops the rpms further when the engine speed mates up to the transmission speed and fluid coupling ceases. This is a completely automatic operation, and there is no control over it. As far as I know, this only occurs while in overdrive...at a steady speed or under slow acceleration (not enough to downshift).

The only way I'd know to check if it's locking up in overdrive (without going to a dealer) is this:

Under slower driving (say, at a steady 30mph), when you *first* push to accelerate but not enough for it to downshift, you normally notice the rpms jump maybe a hundred or two right before it begins to accelerate, right? This is the engine side of the torque converter "fluid coupling" the transmission side where it can begin to take the extra load of accelerating a two-ton truck, and causes the engine rpm to be slightly higher than the transmission rpm. (This also happens to be a source of heat.)

Now, when the torque converter is in lock-up mode at a steady speed in overdrive (say, at your 75mph), and you push to accelerate at that same slow rate without causing a downshift, you shouldn't see *any* initial rise in engine rpm before the acceleration starts...because theoretically it should already be "locked" to the transmission.

If you do, however...I would suspect a torque converter lock-up issue.

 

Erau- That kinda makes sense to me. Ill hit the highway tonight after work and see if I can catch it, although from memory, I definitely notice the rpms raise at lower speeds like 20-30, and at higher, with the speed limits around here she cruises 65ish at about 1700. I swear it was 1500-1600 for 75mph when I bought it though.

 

Welcome to the forum! I do not have an answer for your problem but I am curious to see if you can pin point it

 

I was out and figured I'd make a few recordings of normal locked/unlocked operation. This is a 3.7L V6, 4-speed, 3.55 gears, but the idea is the same.

Steady at 26mph, then slowly pressing the gas to accelerate, you'll notice the rpms jump a few hundred before the acceleration begins. This is the rpm where "fluid coupling" for this particular load has taken place:

[youtube]2vrEVkKmsIk[/youtube]


Next at 40mph, same idea but ever more slight increase in rpm as the gas is pressed while the torque converter is still unlocked. This was done in "Tow/Haul" mode to ensure it was out of overdrive and unlocked:


[youtube]NqoXdPONtFI[/youtube]


Finally, at 70mph, you'll notice there is no change in rpm before the truck begins to accelerate. This is because the engine and the transmission are already "locked" together while in overdrive, just as if it was a standard clutch:


[youtube]N2798Kaw4yI[/youtube]


Now, with 3.55 gears and the 4-speed at 70mph, it turns 2000 rpm (the camera was at a slight angle to the tachometer so it might have appeared 2100). I almost have a hard time believing you were running 1500-1600 at 75mph, because even if you had the longest gears available at 3.21 (and hypothetically running the same engine/transmission as me), you'd still only be running 1808 rpm at 70mph...Even higher at 75mph.

Do you know which gear ratio you have? Maybe we can find out from other 4.7L owners with the same ratio what they turn at 75mph.

 

I did not have that done I will have to get that done next time I change the fluid. Thanks for the info.