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TBSS letting go and hitting rev limiter @ WOT

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Old 04-27-2007, 06:11 AM
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Default TBSS letting go and hitting rev limiter @ WOT

I just got my cooler installed and temps have been a maximum of 178. Car feels smoother and I got 19.5 mpg on the ride back from the shop. I then decided to give it a little punch.. Well, once the car got up to 4.5k it was like it was thrown into neutral and it just hit the rev limiter (not quite as fast as neutral, but not normal).. I believe power was still being applied to the ground, but not so much.. Looking at the scanner log it looks like it was in 4th from the initial punch up until the part where it shot up to redline in which case it was then in 2nd. The car is not throwing any transmission related codes and all gears seem to work just fine when thrown in "manual" mode.

What should be on my shopping list for new parts? I'm thinking I should put the stock converter back in too.
Old 04-27-2007, 12:22 PM
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I'm thinking this could be a drop in line pressure. This happened the same day of the cooler install. If it was a hard part, it would've shown signs or gave out then.. Why now.. why under cool temps? Thats why it shifts fine under normal conditions too. No fluid leaks either.. When it goes WOT it seems it cannot achieve the desired line pressure to shift or hold tight so it just slips and hits the rev limiter.

Does this sound right? It seems like the most logical hypothesis. I mean what are the chances of a hard part giving out on the same day as a cooler install (yes, the cooler is working fine)..
Old 04-28-2007, 03:32 PM
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Bump in an attempt to relieve my uneasiness/uncertainty
Old 04-28-2007, 04:32 PM
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What gear or gears doe it do this in 1-2 2-3 etc ?
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Old 04-29-2007, 08:17 PM
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2nd gear roll.. Have not tried first. These have 4.11s stock so it would be a very quick limit bang... dont want to hurt or risk anything.. I havent even driven the car in 3 days.. I'm just about to go out right now.. I'll log with hpt but i dont plan on going wot.. Thank you very much for replying.
Old 04-29-2007, 09:34 PM
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Have you done any tuning for the 3400 TC?
Old 04-29-2007, 10:25 PM
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Yes sir I have. Lock up points, shift points, TCC PWM Min/Max.. I have had the converter for a few months now and everything was fine until the cooler install. Go figure huh?

I just confirmed that this also happens on the 1-2 shift.. Right around 4.75K rpm it just slips to redline. The only reason it would do this is because there isn't enough pressure to hold tight correct? What should my line pressure be just before a 1-2 WOT shift?

Thanks a lot guys.
Old 04-29-2007, 11:01 PM
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Originally Posted by Blades
Yes sir I have. Lock up points, shift points, TCC PWM Min/Max.. I have had the converter for a few months now and everything was fine until the cooler install. Go figure huh?

I just confirmed that this also happens on the 1-2 shift.. Right around 4.75K rpm it just slips to redline. The only reason it would do this is because there isn't enough pressure to hold tight correct? What should my line pressure be just before a 1-2 WOT shift?

Thanks a lot guys.
The line pressure is usually around 210-230 with the trans go kit installed. I really do not think that installing a cooler would cause the problem that you are having maybe just a coincidence. If the problem you are having is on the 1-2 shift it sounds like you have a burnt band or a cracked accumulator piston. Good luck and let us know if there is anything that we can do for you.
Old 04-29-2007, 11:33 PM
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Thank you very much. My "TCC Line Pressure" is much lower than that. It only reaches a maximum of 120psi. Wouldn't a faulty cooler install show a drop in fluid pressure? I am bringing it back in tomorrow. Either way I will be getting some parts down the road.

My symptoms don't really sound like all the other guys that were having band problems. Its more like this guy:

http://www.trailblazerss.com/forums/...showtopic=4253

I will let you know. Reccomend sonnax servos and all new upgraded bands? I'd love to make this thing near bulletproof without actually purchasing a new transmission. Hell, what I'd really love to do is have a 6spd manual in this.. However, it just doesn't seem possible.
Old 04-30-2007, 08:23 AM
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maybe a bad Sprag?
Old 04-30-2007, 04:47 PM
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Dropped the pan today and the fluid looked immaculate, there were some metal pieces on the magnet. Smaller than a grain of salt in size so no worries there. The gasket for the trans pan was not changed and fluid was leaking. They also did not change the filter when the converter was installed. So now that is being done...

If this does not work out I'm going to put the stock stall back in.

JGKadell: I have heard of sprag failures on the TBSS before. What are the symptoms? The hardest part about pinpointing TBSS trans problems is that ALL of them have trans problems. heh. shoulda been a M6. BTW Nice times on your car!
Old 05-11-2007, 12:39 AM
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Update: Fluid change, filter change, pan gasket change.. Now its perfect.



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