I am assuming you mean when its in 4th gear cruising and you give it a little gas it slips. Which could just be the converter unlocking it will unlock with a part throttle tip then lock back up. If your not sure try this. Find the TAN WIRE WITH A BLACK STRIPE in the trans harness splice into it then run to a switch and then to ground. get cruising to cruising speed in 4th then turn on the switch to ground the wire. This will force hard lockup.Then try it if it dosent do it whenyou tip in that way its just the PCM locking and unlocking the converter as you give it throttle, This would be normal and would feel like a slip . You can have the tune altered to change the amount of throttle before it unlocks if you like if thats the case

 

I have tried this and it still slips. I can tell it's slipping even with the converter unlocked. Just a bit of throttle(WAAAAAYYY less than it would take to unlock the converter) will make it slip. If I slowly ramp up the throttle it will hold fine. Remember, I don't have any PWM, so the converter is either locked or unlocked, and when it unlocks there is absolutely no mistaking that it just unlocked. I can get on it pretty good locked in 3rd gear and the TCC holds fast, so I know the clutch is good. I really really really wish you were right, but there is definitely something else going on.

Like I've said, I noticed this problem BEFORE the tranny was even capable of locking up(DTC from missing PWM solenoid), so it is definitely not the converter. I really appreciate everyone's help, and I apologise if I come off as a dick, because that is definitely not my intention. I really do value your input!

Let's assume for the sake of argument that the TCC is completely out of the picture. Where else can I look? Should I remove the valvebody and check the 4th gear accumulator, or perhaps hook up a pressure gauge and measure pressure in the various gears as well as when the problem occurs?

 

One last try before I start taking things apart.........Any ideas aside from the TCC?

 

Well remember 4th gear is jus the band coming back on , The same band that makes second. difference being the 3-4 clutch is on with it. Now I have seen with excessive band clearance cars have a good second but not hold well in 4th so that make be something to look at. But theres also the possibilty the 3-4 cluthes are going they actually work harder in 4th than they do in third because of the higher ratio,

 

That makes sense, though 3rd gear holds like a champ, and I cannot fathom that the amount of throttle(very little) it takes to make it slip in 4th is causing the 3-4 clutches to slip. Excessive band clearance could be somewhere to look though.

Isn't there a separate accumulator for 4th gear, located under the valvebody? Could there be a problem there, like a cracked piston or something?

Just remember that it slips for roughly 1-2 seconds and then holds fast, like it's taking time for fluid pressure to build up somewhere......

 

Well, it's been a couple weeks and I figure I might as well get to diagnosing this before it turns into something worse. Experts, tell me where to start looking! Should I hook up a pressure gauge and look for XXX amount of pressure, or should I jump in and start taking apart the accumulator/servos and look there?

I guess the main thing I am wondering is what is done differently to apply 2nd/4th gear????? The same servo is used, correct, but different accumulators?

Where do I begin?????????????