torque converter locked up at stop light

kleake

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Had an odd and surprising thing happen just now. Sitting at a stop light idling, after about a minute or so the torque converter locked in and I lunged forward. Barely stopped it before hitting the car in front of me but the engine died. Neutral, started up, put it back in gear and all was good for about 15 seconds and it did it again. Waited for the light to turn, then restarted and drove on and everything seemed normal. Got back to work and went to back into my parking space and while backing up slowly, it locked in again. Bumped it to neutral before it died and then back to rev and it engaged normally. Just as I was stopping moving it engaged again killing it. Sat there for a second, started it up put it in D and R for about a minute each and it never locked in again. Any thoughts?

On a side note, i've NEVER been happy with this tranny. Weird shifts, flares some of them pretty extreme, then perfect shifts the next time. Running Gear-head tunes with some shift work which has majorly helped, but not solved it. Tranny was rebuilt about 70k ago. I don't think it's clutches or anything like that, it's just the shifts are never predictable. Drive it easy and it does ok, but ya just never know what to expect when you are WOT.
 

sootie

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Weird. Sounds like the TCC solenoid is acting up.
 

Zeb

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My experience with a 6.4/5R110 that acted like this it had several TCC solenoid codes.
A lot of friction material in the pan from clutch failure.
I think your trans is dying.
 

kleake

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Not getting any codes, its holding fine under power, and the weird shifting hasn't changed over the last 50k miles, just today the TC started locking in. I dropped the pan and put in a new PCC solenoid a few months back that helped, fluid was clean. I had put in a cheapie a few years back and just wasn't happy with it. The new one is OEM and works well. I don't think the tranny is dying, but I sure do wonder if a new set of solenoids would correct things.

On the way home it never locked in at a stop, but just as I touch the throttle it intermittently would engage and disengage until it was commandeered to lock around 45mph. One thing to note, the TC was replaced when I did the engine work about 5K ago. Previous TC wasn't holding under heavy load while towing. This is an extra low 4 disk converter. Do you think the TC could be causing it?

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kleake

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I was going off memory with the PCC solenoid, it was actually the PC-A solenoid that I replaced a while back. Originally it had a step as it went into reverse. You would feel it bump in but not lock fully, then a half second later it would lock in fully. Swapped the PC-A with a new one, but wasn't OEM brand. It fixed the two step reverse, but I noticed a few times backing my 5th wheel up a hill into a campsite that reverse would slip. It wasn't bad, and only did it under heavy load so I dealt with it for a while. Eventually I swapped out the PC-A with an OEM solenoid and all has been good other than I still have the odd shifts at random, although they are improved with this new PC-A.

If the TCC solenoid is causing this random lockup at idle, I'm wondering if I would benefit from just throwing in a full set of solenoids in hopes of correcting some of the other issues I have dealt with. The trans was rebuilt around 180k miles and now has 250k on it, but has always had weird shifts at random. If I might benefit from that, where it the best place to get them and is there a full set that is cheaper than buying individually? I haven't went digging too far on this yet, but remember seeing that as an option somewhere a while back.
 

kleake

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Welp, it gets more exciting (expensive) every day. All new solenoids, first 4 shifts were good. Each time I was adding a little more throttle so it could learn, and on the 5th shift cycle, at about half throttle, at either the 3-4 shift or converter lock I got a BANG and then I was coasting. (I wasn't paying close attention to which shift because all had been good so far). No forward, no reverse, no noises when putting it in gear. I know something broke, but I'm not sure what. There wasn't even enough shifts to confirm these solenoids fixed the odd shifts, but it was feeling like it improved up to that point.

Sitting on the side of the road waiting for a tow back to the house

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sootie

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If you put a pressure gauge in the test port and have good pressure in all the gears, my bet is that the Intermediate shaft snapped.
 

kleake

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I am thinking you are right. I'll test that probably Friday. Next question though, why? Did it try to engage 2 gears at once or?

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sootie

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if it was fatigued, the slightly harsher engagement, from learning, when under moderate throttle could've been the straw that broke the camels back. while its possible there could've been a bind scenario, i doubt it.

if you have no pressure at all when you test it, it could be a broken input. those are an easy fix. just shake the broken bit out of the converter and slide the shaft out of the pump-replace and done. intermediate requires the trans to be torn down. more than likely the intermediate though based on when it broke. All of the one i have seen have broken on either TC lock or 3-5 shift.
 

kleake

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That would make sense since intermediate is original and I have a billet input with 70k on it.

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kleake

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Pressure is about 110psi, put it in gear, pressure drops to 75psi for a second, then starts climbing. Hits about 300, then drops back to 125, holds a second, then starts climbing again. Reverse and D do the same except Drive climbs to about 350, then drops and acts the same.
 

kleake

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intermediate.

Next question, I see several comments (dated) about billet intermediates failing because they don't absorb the shock as much and the way the splines are cut compared to stock. Thoughts on which is better? Leaning towards billet thinking they have corrected that issue by now.
 

sootie

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Next question, I see several comments (dated) about billet intermediates failing because they don't absorb the shock as much and the way the splines are cut compared to stock. Thoughts on which is better? Leaning towards billet thinking they have corrected that issue by now.
I broke a stock intermediate and replaced with billet. Deep in the 700hp range with no issues
 

kleake

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I broke a stock intermediate and replaced with billet. Deep in the 700hp range with no issues

That makes me feel better. I don't know what my HP range is, but I know i'm not that far. Possibly 600 or slightly over is only a guess. I know I cringe every time I get on it, because I know those little u-joints are holding on to all they can! I have been tempted, but never done a 4wd launch either. I just figure my wallet wouldn't like that too well.
 

sootie

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That makes me feel better. I don't know what my HP range is, but I know i'm not that far. Possibly 600 or slightly over is only a guess. I know I cringe every time I get on it, because I know those little u-joints are holding on to all they can! I have been tempted, but never done a 4wd launch either. I just figure my wallet wouldn't like that too well.
That's the last thing you need to worry about lol
 
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Kleake,

Try to air check the packs as you come apart. You can start this process once you pull the Solenoid body off and just before you pull the pump off.

Despite some broken hard parts, it would be nice to know if you had a leaky pack that was causing the erratic shifting. let me know if you need a diagram that shows where all the air check spots are for the individual packs. I don't have it here at my apartment, but I know it's in my toolbox somewhere.
 

kleake

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Kleake,

Try to air check the packs as you come apart. You can start this process once you pull the Solenoid body off and just before you pull the pump off.

Despite some broken hard parts, it would be nice to know if you had a leaky pack that was causing the erratic shifting. let me know if you need a diagram that shows where all the air check spots are for the individual packs. I don't have it here at my apartment, but I know it's in my toolbox somewhere.

Hey that would be great! I would definitely like to check that before I tear too deep into it.
 

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