Problems with Torque Converter Lockup
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From: Deland, Florida
Problems with Torque Converter Lockup This past week I went from a Yank SS3200 stall and stock trans to an FTI 3600 stall and a built trans. Everything worked fine before the swap, never had any trans tuning done. With the 3600 the converter will not stay locked. When it locks it locks unlocks locks unlocks until I let my foot off the gas and allow it to lock. If I give it gas and it unlocks it goes through the same cycle.
I did a search and saw the thread about the misfire counts......would this fix my lock unlock cycling? Someone suggested my converter lock vs unlock points were too close together. I have EFI Live, could someone point me in the right direction with that program?
Thanks!
I did a search and saw the thread about the misfire counts......would this fix my lock unlock cycling? Someone suggested my converter lock vs unlock points were too close together. I have EFI Live, could someone point me in the right direction with that program?
Thanks!
I actually have a similar problem to where my 3800 stall slips under heavy acceleration (as it should) but when the desired RPM range is met it doesn't fully lock and is still partially slipping leaving my car sounding like a frieght train but no hard acceleration happening.
You need to get someone to fix your misfire tables in the
tune.
Slip is a whole different problem, that wants as a minimum
the TCC duty set to full time max but maybe more line as
well.
tune.
Slip is a whole different problem, that wants as a minimum
the TCC duty set to full time max but maybe more line as
well.
Thread Starter
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From: Deland, Florida
All my misfire table has already been set to 32767. Today I am going to try setting min/max misfire temp to 141/142. Is there anything else I should try if this does not work?
Staging Lane
Joined: Jan 2009
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From: Bella Vista, AR
Possible Explanation Frank at performabuilt can explain to you exactly what is going on. If you look on their website he explains what GM did wrong that they fix in their transmissions to not allow partial lock up. Below is link to their website and a description of what GM did wrong and how they fixed it.
http://www.performabuilt.com/level-1.html
"We also eliminate the partial lockup function GM mistakenly engineered into the 4L60E transmission, thus eliminating converter shudder, premature converter clutch failure, and the well known code 1870, which causes high "line pressure", no fourth gear, and teeth cracking shifts at low throttle. Lockup is either OFF or ON, not slipping off and on as it did with the factory PWM working. This does not affect performance, but it does have the added advantage of increasing low speed fuel efficiency, which at today's fuel prices is like getting a bonus. In addition this mod along with others allow us to use later valvebodies on older units to improve performance and increase interchangability and reliability."
I went ahead and purchased their level 3 invincible just to play it safe.
http://www.performabuilt.com/level-1.html
"We also eliminate the partial lockup function GM mistakenly engineered into the 4L60E transmission, thus eliminating converter shudder, premature converter clutch failure, and the well known code 1870, which causes high "line pressure", no fourth gear, and teeth cracking shifts at low throttle. Lockup is either OFF or ON, not slipping off and on as it did with the factory PWM working. This does not affect performance, but it does have the added advantage of increasing low speed fuel efficiency, which at today's fuel prices is like getting a bonus. In addition this mod along with others allow us to use later valvebodies on older units to improve performance and increase interchangability and reliability."
I went ahead and purchased their level 3 invincible just to play it safe.
Staging Lane
Joined: Jan 2009
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From: Bella Vista, AR
Just FYI There are tables in the PCM which tell the lock-up to release as percentage of throttle opening and specific MPH in each gear.
The converter clutch has only a 1 inch wide surface of kevlar trying to deal with all the power of your engine and easy to destroy if you have some HP.
I have always configured the transmission tables to allow lock up only in 4th gear and then only under certain conditions - see attached spreadsheet.
The converter clutch has only a 1 inch wide surface of kevlar trying to deal with all the power of your engine and easy to destroy if you have some HP.
I have always configured the transmission tables to allow lock up only in 4th gear and then only under certain conditions - see attached spreadsheet.
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It definitely was NOT a mistake that lockup is modulated in an OEM converter... modulation makes it smooth and much less noticeable vs a hard jerk that you get with on/off engagement.
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Brett Foote Thread Starter
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Thanks I'll give that a try. Setting the min/max temps to 141/142 didn't help. It locks up if barely any throttle is applied to cruise....if I try to accelerate it will surge.
Staging Lane
Joined: Jan 2009
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From: Bella Vista, AR
Question Are your sure the transmission builder did everything correctly when making modifications to the valve body and other internals? If it has never worked correctly since the install and everything worked correctly before this with the PCM settings you were using, this makes the new transmission sound like the problem. I still say Frank will be able to tell you what is going on within 2 minutes of hearing your problem.
Thread Starter
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The guy that built the trans is a reputable guy that frequents this site. I also swapped converters too at the same time as getting the trans rebuilt....went from a tight 3200 stall to a loose 3600 stall....I think I just got lucky with the 3200 stall and did not require any tuning. I'm going to try the PWM increase and see how it goes. Thanks everyone for the input thus far
Last edited by 2kta--89formula; Feb 21, 2011 at 10:53 PM.
Thread Starter
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From: Deland, Florida
As an update......I talked to my trans builder....we decided to increase the line pressure 5%, raise my 4th gear shift point, raise my lockup speed, and just drive the car. I don't know at this point what the deciding factor was but it seems to work just great now (not wanting to speak too soon but it seems fixed).
