Tcc Problems

Now my question is, since I was having issues with the Tc clutch in the first place could it be possible that the torque converter is shot? Once the car is cool it will drive and engage with no problem until it heats up even in park it heats up.

Well that certainly is a possibility. If you could smell the trans burning, then I'd have to say absolutely. When it's hot, it's supposed to lock the TC up even faster. Then again, if it's unable to engage fully, it would certainly overheat and start burning sh*t.
Weird that it works when it's cold, and you say it gets hot in Park? You may have a fluid flow problem?
Again, drop the pan and have a look. What's inside, or not inside that filter is wonderful evidence.

I would say that instaling a trans cooler with fan would do wonders.these transmissions run kinda hot.as far as I know there is no optimum trans operating temperature like an engine has.the cooler you keep em the better

Abaddon wrote:

Weird that it works when it's cold, and you say it gets hot in Park?

Scott,
I know the PCM will not allow lock up when the transmission is very cold. What if the Transmission temperature sensor is defective? Might it tell the PCM it is cold when it is hot? I'd guess you need a tech 2 scan tool to check that reading out. Just a thought.

never mind, It sounds like the transmission fluid is overheating.

Here's the noise https://www.youtube.com/watch?v=xB03JdxIDT0&feature=youtube_gdata_player

Is it me, or does that sound like a box of rocks?

Quote :

I know the PCM will not allow lock up when the transmission is very cold. What if the Transmission temperature sensor is defective? Might it tell the PCM it is cold when it is hot? I'd guess you need a tech 2 scan tool to check that reading out. Just a thought.

Would think this situation would set a code (SES) for sure. PCM has coolant temp to compare. Trans temp is one of the more critical parameters for the PCM to track, imo.

What is TCC RPM about? I added it to my scanner recently. When should I see higher RPMs?

Also, if I cruise in 2nd gear and leave her run at ~3k RPM for an extended length of time, will this hurt anything except for my MPGs?

THANKS GUYS!

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Also, if I cruise in 2nd gear and leave her run at ~3k RPM for an extended length of time, will this hurt anything except for my MPGs?

As long as you are keeping engine coolant and transmission temps in check, and have adequate oil, the only downside to running at 3k RPM is added engine wear. For each cycle of your cylinders & valves, there is a slight amount of wear to the internals - 2X as much as at 1500 RPM. So theoretically your rings and upper valvetrain would last about half as many miles if you ran this way constantly. On the other hand, loads to the crank bearing (bottom end) would decrease, so less wear & stress there.

In short, it shouldn't hurt anything, just make sure your engine is up on maintenance, and watch the temperatures.

PS - 2nd gear spins at 3kRPM for low cruising speeds in the city, but quickly moves to 5k as you approach freeway speeds. I would recommend 3rd gear for the interstate.

Cool!

What about TCC RPM speeds? What's that all about? When should I see low and high TCC RPM speeds?

AA wrote:

Quote :

Also, if I cruise in 2nd gear and leave her run at ~3k RPM for an extended length of time, will this hurt anything except for my MPGs?

As long as you are keeping engine coolant and transmission temps in check, and have adequate oil, the only downside to running at 3k RPM is added engine wear. For each cycle of your cylinders & valves, there is a slight amount of wear to the internals - 2X as much as at 1500 RPM. So theoretically your rings and upper valvetrain would last about half as many miles if you ran this way constantly. On the other hand, loads to the crank bearing (bottom end) would decrease, so less wear & stress there.

In short, it shouldn't hurt anything, just make sure your engine is up on maintenance, and watch the temperatures.

PS - 2nd gear spins at 3kRPM for low cruising speeds in the city, but quickly moves to 5k as you approach freeway speeds. I would recommend 3rd gear for the interstate.

3rd gear in our 4T6xE transmissions is same, essentially, as the top gear in the 3 speed turbohydramatics. A version of that original transmission, the THM400, is still in use in the military Humvee. From Wikipedia:

The THM400 was the first three-speed, Simpson-geared automatic to use overrunning clutches for both first and second gear reaction, a feature that eliminated the need to coordinate the simultaneous release of a band and application of a clutch to make the 2-3 gear change. Owing to this feature, as well as the use of a large, multi-plate clutch to provide second gear reaction, the THM400 is able to withstand very high input torque and an enormous number of shifting cycles, as would be encountered in frequent stop-and-go driving. As a result, it has met with considerable success in commercial vehicle applications.

For 1987, GM changed the nomenclature of their Turbo Hydramatic transmissions — the THM400 was renamed to the '3L80' (three forward speeds, longitudinal positioning, and an arbitrary 'strength' of 80, the second highest such rating assigned). The 3L80HD was introduced in 1987 as the HD unit used in passenger trucks. In 1991, a four-speed overdrive version, the 4L80-E, replaced the THM400 in Chevrolet/GMC pickups, vans, SUVs, and commercial vehicles. The 4L80E (and its successor 4L85E) was the first Hydramatic to incorporate electronic controls — almost all of the THM400/3L80/3L80HD's components are interchangeable.

So our 'version' of the turbohydramatic is the 4T65E:

4 four forward speeds incl overdrive
T transverse
65 strength relative to GM standard... usually the 8x goes with 8 cyl, 6x goes with 6 cyl, and 4x goes with 4 cyl
E electronic

I understand that in the old GM nomenclature its a distant descendant of the THM125 (direct descendant of the GM THM 440-T4).

My transmission rebuilder built my 4t65E into an 80 - sort of. Many of the "strength" components are interchangeable. The transmission ran far longer as a rebuilt than it did from the factory, it ran until his genius associate backfilled it with Dex III in routine maintenance; it took about 25,000 miles for that to grenade the TC. Definitely Switch To Dex VI BUT Never Switch Back.

One final thing Charlie. The 4T6x transmission is designed for some robustness for various types of driving. Your issue however, might be that if you defeat the engineering by running around in second gear or whatever you are not going to enjoy the benefit. The transmissions are plentiful, you may want to scope out a junkyard swap-in replacement. a full service yard (most likely rural) that does engine/transmission replacements will probably work with you to wait for one to come in at pricing that you can stomach as long as you're realistic about the cost and can stomach the wait. You'll have to make a bunch of calls to find a yard that will play ball with you on this. A lot of the late 90s GM cars with 4T65Es are coming off the road, though, so if you can find the right yard in your area this should be easier than you think. Bottom line is you can do what Aaron is talking about but it's going to cost you. The gas mileage hit and shorter life is kind of like being nibbled to death by ducks (they have no teeth, so you die laughing, not from the bites).

Good info ^^^. The analogy of the ducks nibbling is appropriate. The MPG hit isn't as much as you'd think under throttle. It hurts you most when the car is coasting - engine braking hinders that wonderful inertia our cars have, which lets it cut through the air with ease. Re: engine wear, this is anyone's guess. Theory and field experience are often different. All I know is, not all, be many, many of my first 246k miles were without TCC lock-up, and lots at 3k and above. Some days I'd drive in 2nd and 3rd for 30 miles to work, just for the fun of it. If you want to feel the "sporty" car within the Riv, this is one way to access it. Torque delivery is truly brutal, to the point of discomfort for some I'm sure. Again, heed the warnings posted above. Not every engine is up for this type of exercise, and when in doubt monitor, monitor, monitor!

I dont usually engine break. Once I get speed, I shift up to 3rd or OD and coast.

I do like keeping her at ~3kRPM tho, it's nice to have that immediate access to power!

OK, so back to TCC.
When will I see higher TCC RPMS? when im in 3rd and 4th and on the highway?

Then in town, TCC should chill out and slow down on the RPMS when im 40mph and under. Right or wrong?


Just trying to understand this stuff better. Thank you!

TCC lock-up depends on load (MPH vs. throttle %), not RPM.

TCC Lock-Up Schedule (OEM) for 4T65eHD:

Note: values apply only for transmission operating within normal temperature range, not engaging cruise control. TCC will not apply in any gear at WOT.

1st gear TCC apply: None, TCC release: None

2nd gear: TCC apply: None, TCC release: None

3rd gear @ 00.00% throttle - TCC apply: 28 MPH, release: 26 MPH
3rd gear @ 06.25% throttle - TCC apply: 28 MPH, release: 26 MPH
3rd gear @ 12.50% throttle - TCC apply: 29 MPH, release: 26 MPH
3rd gear @ 18.75% throttle - TCC apply: 38 MPH, release: 26 MPH
3rd gear @ 25.00% throttle - TCC apply: 50 MPH, release: 27 MPH
3rd gear @ 31.25% throttle - TCC apply: None, release: 33 MPH
3rd gear @ 37.50% throttle - TCC apply: None, release: 41 MPH
3rd gear @ 43.75% throttle - TCC apply: None, release: 50 MPH
3rd gear @ 50.00% throttle - TCC apply: None, release: 60 MPH
3rd gear @ 56.25% throttle - TCC apply: None, release: 70 MPH
3rd gear @ 62.50% throttle - TCC apply: None, release: None
3rd gear @ 68.75% throttle - TCC apply: None, release: None
3rd gear @ 75.00% throttle - TCC apply: None, release: None
3rd gear @ 81.25% throttle - TCC apply: None, release: None
3rd gear @ 87.50% throttle - TCC apply: None, release: None
3rd gear @ 93.75% throttle - TCC apply: None, release: None
3rd gear @ 100.0% throttle - TCC apply: None, release: None

4th gear @ 00.00% throttle - TCC apply: 40 MPH, release: 38 MPH
4th gear @ 06.25% throttle - TCC apply: 40 MPH, release: 38 MPH
4th gear @ 12.50% throttle - TCC apply: 40 MPH, release: 38 MPH
4th gear @ 18.75% throttle - TCC apply: 46 MPH, release: 38 MPH
4th gear @ 25.00% throttle - TCC apply: 59 MPH, release: 41 MPH
4th gear @ 31.25% throttle - TCC apply: 79 MPH, release: 44 MPH
4th gear @ 37.50% throttle - TCC apply: None, release: 53.0 MPH
4th gear @ 43.75% throttle - TCC apply: None, release: 62.0 MPH
4th gear @ 50.00% throttle - TCC apply: None, release: 71.5 MPH
4th gear @ 56.25% throttle - TCC apply: None, release: None
4th gear @ 62.50% throttle - TCC apply: None, release: None
4th gear @ 68.75% throttle - TCC apply: None, release: None
4th gear @ 75.00% throttle - TCC apply: None, release: None
4th gear @ 81.25% throttle - TCC apply: None, release: None
4th gear @ 87.50% throttle - TCC apply: None, release: None
4th gear @ 93.75% throttle - TCC apply: None, release: None
4th gear @ 100.0% throttle - TCC apply: None, release: None

Example 1:

3rd gear @ 25.00% throttle, 45 MPH: TCC no apply (level road)
3rd gear @ 25.00% throttle, 50 MPH: TCC apply (level road)
3rd gear @ 25.00% throttle, 27 MPH: TCC no apply (up hill)
3rd gear @ 25.00% throttle, 45 MPH: TCC no apply (up hill)
3rd gear @ 18.75% throttle, 38 MPH: TCC apply (at crest)
3rd gear @ 06.25% throttle, 35 MPH: TCC apply (down hill)
3rd gear @ 25.00% throttle, 45 MPH: TCC apply (level road)

Example 2:

4th gear @ 25.00% throttle, 60 MPH: TCC apply (cruising speed*)
4th gear @ 43.75% throttle, 62 MPH: TCC no apply (half throttle)
3rd gear @ 56.25% throttle, 65 MPH: TCC no apply (3rd downshift)
2nd gear @ 87.50% throttle, 70 MPH: TCC no apply (2nd downshift)
4th gear @ 25.00% throttle, 85 MPH: TCC apply (4th upshift)
4th gear @ 00.00% throttle, 80 MPH: TCC apply (throttle release)
3rd gear @ 25.00% throttle, 70 MPH: TCC apply (cruising speed*)

* cruise control NOT engaged.

Right, but isnt the TCC always spinning? Hence the differences in RPMs?

anyone know of any good pics/diagrams to see this in action? Im a visual learner..

This is what the TCC solenoid looks like?


And the solenoid pushes what? does what? is there some kind of gear/plate/clutch involved after the solenoid?
What engages with what?

Does each gear have its own individual solenoid to engage?



What does torque converting even mean? when the TCC engages/locks up it is bypassing torque or delivering torque? huh?

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Right, but isnt the TCC always spinning? Hence the differences in RPMs?

The Torque Converter Clutch is a mechanical coupling, so when engaged it eliminates the fluid coupling of the torque converter. Whether it's spinning or not isn't relevant, really. What matters is when it's engaged (energized by 12vDC), it couples the flex-plate to the output shaft without the need for a fluid coupling. When this happens, there is a 1:1 drive ratio between the engine and the axles, eliminating any slip.

In 1st and 2nd gears, there is no lock-up. The TC is slipping via a fluid coupling.

In 3rd, the TCC is allowed to lock-up part of the time.

In 4th gear, TCC is commanded to lock-up most of the time.

The difference in RPM (I think) you are referring to is with TCC lock-up vs. no lock-up. When locked-up, the RPM will be lower than when not, because the TC is allowed to slip, which increases input RPM for a given output speed.