So I have a BIG problem. Long story! My Brother has a 2007 Trailblazer SS and has upgraded his trans and stall. This spring we installed a RPM LVL 6 trans and a Yank SS4000. He put a total of just over 1000 miles on the set up before we pulled it back out. While driving and the converter locked it would continue to come open and closed as well as the converter slipping. We contacted both vendors and received advise from both. We confirmed we had converter slip by manually locking the converter in fourth gear with a tech 2 scanner. It showed up too 800 RPM under light throttle conditions. So we pulled them both and shipped the converter back to Yank and then actually brought the trans back to RPM. RPM looked through the trans and found no issues. They were great and offered amazing amounts of help! They also refreshed the trans for my brother at next to nothing for cost. They found no issue and put the freshened trans on the dyno w/ a house converter and verified that their converter would lock and not slip. they even verified this by applying a brake on the output shaft killing the dyno to prove the converter would stay locked. So we know and verified the trans works and no issues. Yank told my brother that they found no issue with the converter and cut and cleaned it. Took care of him on the labor cost as well. So today we reinstall the trans and converter set up all new and tested and same freaking issue. The converter slips under light acceleration while locked and comes open and closed. We only put a total of 6 miles on it today so that we don't put a bunch of clutch material through all of the new parts. Trans has a stock/ factory trans file in the tune and we installed a PCM of NC trans cooler. I have a 00 SS with an FLT and Vig set up and no issues ever. I have installed multiple set ups in my car and buddies car and have never had this issue. I know the trans is installed correctly and am stumped. I don't know where else to look. We even had Yanks tuner look at the tune and he stated that it looked good. I don't think the misfire tables have been messed with to much but in the 1000 miles we drove it on the first set up from the spring it never through a check engine light. So long story short my brother now has like 4-5 grand in this set up with the original purchase plus the refreshes and still has a new set up that is broke! ANY HELP IS APPRECIATED. Thanks in advance guys!

Matt

 

Given that both Yank and RPM double checked their product and their highest reputation, perhaps you have an electrical problem related to the TCC solenoid. The TCC solenoid is connected to +12V within the trans harness; the other lead feeds through the harness to the PCM which pulls it down to ground (0V) to enable lockup. If there is resistance in the lead or the PCM cannot pull all the way down to 0V, you likely would have slippage.
With the engine off, pan off, ignition on and a scanner connected, I would measure the voltage on the TCC solenoid. (You can use a sewing needle to poke through the insulation; ATF is not corrosive to wiring.). One lead will always be +12V, but when the scanner enables lockup the other lead should drop close to 0V (I would expect around 0.5V). If its something like 5V, the problem is the wiring harness or PCM.

Another related potential issue is the TCC PWM solenoid and related TCC valve. While the stock setup uses PWM for a smooth/gradual apply and release, most performance trans (and shift kits) replace the PWM valve with a on/off valve. I'm not sure of this, but if the PCM does not send the correct PWM signal (duty cycle) to this solenoid, the lockup may not apply fully. You would probably need to try a different PCM to test this. I don't know if a bad tune could mess this up.

You have an unusual problem and I am not certain of my advice, but this is what I would do. Perhaps it is something simple, but it sounds like you, Yank and RPM and already considered the usual suspects.

 

thank mrvedit! I inspected the harness for any pinches in the casing yesterday. It didn't appear that there was chaffing or area's that we could have possibly pinched between the bellhousing and engine. The nice part about the trailblazer is there is a ton of room under the thing. With the drive shaft out I can literally sit completely upright under the truck while working on it (Not really a big guy either so that helps). I cant imagine that the PWM system or the solenoid would be faulty as they are brand new and worked and held on the Dyno. It very well could be a faulty TCM (separate on the trailblazer). Although prior to the install the stock unit worked perfect with no issue. thank you for taking the time to respond. Hopefully someone else may chime in with some other suggestions as well and we will look at yours today! will keep everyone posted

 

My older Y3000 kept "locking & unlocking" until I had the vehicle "dyno tuned" (Sara 2001 Z28).

The tuner adjusted the shift points, and various other settings to have the vehicle shift properly.

Because of the converter change, my vehicle computer was "hunting" for the correct gear @ various rpm's.

 

Can anyone verify if tuning will actually cause the converter to slip? It locks and holds under very light throttle. But if you go to pass someone or go up a hill then it slips like crazy. Is it possible to increase the lock up clutch pressure with a tune????

 

Of course it will (or can) because the PCM controls line
pressure, and the TCC and trans frictions are all subject
to that. TCC has the worst of it because there is a further
variable knockdown of pressure there ("slip learning" is
one bit of suck, to eliminate; original programming is poor
for steady state line pressure as well).

Whether this -is- the problem, probably wants you to put
a pressure gauge on the trans, in operation, and scan
for the important things that relate to torque holding
capacity of the trans in-the-moment.

Your on/off activity, that's misfires, similarly fixable,
probably just from the lighter converter mass than stock.

 

Hooking up a pressure gauge is always a good idea with any trans problem, although I would expect that RPM checked it.
I think that problems with misfile tables would simply disable TCC, not make it slip. That reminds us that you should scan for codes as not all codes immediately turn on the MIL (check engine light).
I have not heard of TCC slippage due to a tuning problem. Until properly tuned, a high stall converter often causes the TCC to be completely disabled.
With the stock tune and stock PWM TCC valve in the trans, the PCM makes very soft engagement and disengagement of the TCC which involves slipping the clutch a bit. This is partly controlled by the TCC Duty Cycle tables (Maximum and Minimum) in the tune. Some people simply tune the Minimum and Maximum tables to all value "96" to disable the soft engagement. Alternatively the PWM TCC valve is often replaced in performance builds with a On/Off valve which also gives a firmer engagement with less slippage. You might ask RPM what type of TCC valve your trans has.

 

Gentlemen,
Thank you for your advise. i can confirm that the converter does indeed lock. i can also confirm that it is a solid quick lock. I am 99% positive that the PWM valve would have been replaced with a on and off valve. ( i am confident in this as i made sure that FLT did this with my FLT 4 in my F-Body) it is a very noticeable difference. I also believe that RPM did verify the line pressure and tested good while putting the trans on the dyno they have. This is the second time it was built. There is no MIL on although we didn't check for codes on the original ( first build) now that it is back together we have only put 6 miles on it and have stopped driving it to eliminate putting clutch material into the trans (as prior) I will find out what the TC duty cycle tables are set too and advise. SO it looks like we need to look at TCC duty cycle and misfire tables. Gentlemen again thank you for your assistance and i will advise after update. thanks

 

You definitely need to get it tuned for the higher stall.. I can almost guarantee this will fix your issues.

 

Starting with a proper tune for a high stall converter is a good idea. I'm not convinced that will solve your problem, but it needs to be done and all kinds of pre-tune problems have been reported here.

 

alright so a quick update. On Friday we installed a new race TCM from PCM For less. They made sure to address the TCC lockup tables and increased line pressure at lower rpm's. Same thing. Truck isn't throwing any codes although we are not driving it long enough to throw one. I was told that it takes about 30 seconds of slip to set or trip a code and it has to be done three times. We are not about to chance putting all that clutch material into these new parts. Looks like we have decided to pull the trans and order another converter. Hopefully we will have this thing done in the next two weeks. Will keep everyone updated. thanks

 

I know mine use to get false misfires and unlock the convertor till I removed the code. It use to start slipping around 2200rpms where I would get false misfires then unlock for a couple mins. Lowered rpms then it would relock.

Id say drive it to a tuner and have them go over it.

 

alright guys so here is the update. My Brother ordered a Precision Industries Vig from RPM last week. It came in yesterday and we did the install last night. We found that the Yank TQ was the problem and faulty. Again let me recap the situation. The Yank converter would lock and fully lock in the way it should. Although when you would put any throttle in it under load the converter would slip. Again we verified this with a Tech 2 and manually locking the converter. So we put the new Vig in it last night and it operates PERFECTLY the first time. Locks right up and can get into the throttle probably close to 40-50 percent prior to the TCM commanding it to unlock. ZERO slip was measured. So much for the Yank Converter. I just hope Yank and my Brother can come up with some sort of refund or deal! My brother didnt want to send it back to Yank as the first Brand New converter from him was tested bad by us and we were told there is no way it the converter. Yank told us it was either the trans or wiring. So we pull it all back apart and then have both items refreshed. Put it back together again after Yank told us he cut and cleaned the converter and found no issues with the same problem. Again the same issue. My brother said it the best WHY TEMPT FATE with yet another Yank converter. Please dont take this as me bashing Yank as it isn't. This forum is so we can all learn from each other and discuss these issues. I am simply presenting the facts and the discussions with Yank and my Brother. ( and all my time doing the trans 3 times)

 

Please also note that i didn't state. Nothing other than the Torque converter was changed last night.

 

I'm not doubting that the Vig converter solved your problem, but I don't recall reading any complaints about Yank converters. Do you have the correct o-ring on the input shaft? Perhaps a slightly stretched one would still seat the Vig converter but be loose in the Yank converter, allowing the TCC to slip.

Anyway glad you got it working; hopefully it doesn't start slipping too in the future.

 

On my truck I ended up dropping my TCC release MPH a few because it also kept locking and unlocking back and fourth . But it sounds like your good to go now !

 

What was the outcome with yank? Id like to know because I'm in the market for a new stall myself.

 

Give us a call at Texas speed. We are using tons of Callies cores with great results. Rather you bought from us or not I'll be happy to help get you rolling on a killer deal!!

 

When you say you changed the pressure, was that the
shift pressure or the force motor tables? Because the
obvious pressure tables go to during-shift, not holding
(steady state) line pressure. There, you have (on some
models, in HPTuners anyway) some access to steady
state pressure "*****" (like TCC-locked adder) but when
I was fighting converter slip (TCI 3000) I found that the
main line commanded was showing 0% at light cruise
and all I could do was bump down the force motor current
at lower load-points to get more actual, delivered pressure.
This was before they added the steady state params to
the menus.

Anyway, give a look to commanded line% and see if you
are still having stock-ish (weak sauce) pressure at cruise.
If so, you may see this problem return with wear or with
weather.

 

I agree with jimmy. I won't necessarily hang Yank on this one. But I guess we will never know the truth now.