Torque Converter Won't Lock Completely
Torque Converter Won't Lock Completely I can feel it "lock" (I see the RPM drop) but sometimes it does not lock completely. There is still about a 200-300 RPM slip when you hit the gas. Sometimes it locks up tight; meaning there no RPM increase when you give it more gas. I hope this makes sence...
I agree with strokedls1. The clutches in most converters are not big enough to lock up for long, you may have burned out the clutch. The only converters I trust to be locked at WOT use bigger clutches or multiple discs.
Fluid is fine and the torque converter (Art Carr) only has 1000 miles on it. The strange thing is that it took me about 6 months to get that many miles on it and it never locked up completely until I made a 100 mile trip in the car. Until then I never drove any more than 30 - 40 miles at one time. I was about 75 miles into a trip before it locked up right. After that it has done pretty good. The strange thing is, if I'm in overdrive and I get on it hard, the car unlocks the converter, downshifts to 3rd. After that, it will not lock up again until the car is stopped for a while and restarted. Explain that ****. 
possible things
- tcc clutch worn out (faulty from the manufacturer). it DOES happen- don't think it can't just because you paid top dollar for a converter
- tcc apply/release valve bore is worn/sticking. is there a shift kit in the car? if so is the transgo valve in there?
-tcc solenoid is not functioning properly (probably a code with this)
- misfires (low rpm) causing it to unlock/not lock. disable all low and med misfire **** in the pcm.
i had similar problems before, turned out to be a bad lockup clutch.
good luck.
- tcc clutch worn out (faulty from the manufacturer). it DOES happen- don't think it can't just because you paid top dollar for a converter
- tcc apply/release valve bore is worn/sticking. is there a shift kit in the car? if so is the transgo valve in there?
-tcc solenoid is not functioning properly (probably a code with this)
- misfires (low rpm) causing it to unlock/not lock. disable all low and med misfire **** in the pcm.
i had similar problems before, turned out to be a bad lockup clutch.
good luck.
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Yes, it is a trango shift kit. The transmission builder made sure to mention that he installed the entire kit and some builders don't. The TC brand is "Art Carr". I know there is more than one thing in the trans. that controls lock-up, so how do you determine which it is? My tuner is supposed to be really good with tuning auto's so I'm pretty sure he took care of the whole missfire thing. Plus, I have no codes and never had a misfire code.
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Some converters (esp. with smaller diameters) just seem
to be under-clutched. Figure that holding torque is roughly
diameter (radius) for the same apply force, with other stuff
like clutch material friction and fluid friction modifiers coming
into play.
The TCC clutch working pressure is a TCC PWM knockdown
of the Force Motor knockdown of the main line. At low "load"
the Force Motor sits there at very low pressure, high current
(0 commanded line pressure) and the TCC has roughly squat
to work with, even if it were wide open. The stock force motor
table is set up presuming stock engine output and stock, large
diameter clutch. Not too surprising that converters with small
not-sticky clutch faces, up against hopped-up motors, see
some elevated part-throttle slip.
Then, there's my suspicion that the PCM tries to "learn" TCC
slip to roughly 50RPM (most likely to minimize tranny pump
losses and improve economy when it "thinks" high line is no
bonus). But fancy learning also means it can slide around
some as tranny temps, fluid pressures at the business end,
do, and the learning is always a bit late.
Anyway, log your commanded line % and your TCC duty %
in the soft-slip regime and see which, or both, are to blame
for wimp holding. I have jacked up my 0%-commanded line
(lowered force motor current about 40%) and set my TCC
duty stuff to have always 98% PWM on that. I believe the
TCC duty %, more is more while on the force motor, more is
less modulated line pressure. Hope that's right; if not, might
explain some things
to be under-clutched. Figure that holding torque is roughly
diameter (radius) for the same apply force, with other stuff
like clutch material friction and fluid friction modifiers coming
into play.
The TCC clutch working pressure is a TCC PWM knockdown
of the Force Motor knockdown of the main line. At low "load"
the Force Motor sits there at very low pressure, high current
(0 commanded line pressure) and the TCC has roughly squat
to work with, even if it were wide open. The stock force motor
table is set up presuming stock engine output and stock, large
diameter clutch. Not too surprising that converters with small
not-sticky clutch faces, up against hopped-up motors, see
some elevated part-throttle slip.
Then, there's my suspicion that the PCM tries to "learn" TCC
slip to roughly 50RPM (most likely to minimize tranny pump
losses and improve economy when it "thinks" high line is no
bonus). But fancy learning also means it can slide around
some as tranny temps, fluid pressures at the business end,
do, and the learning is always a bit late.
Anyway, log your commanded line % and your TCC duty %
in the soft-slip regime and see which, or both, are to blame
for wimp holding. I have jacked up my 0%-commanded line
(lowered force motor current about 40%) and set my TCC
duty stuff to have always 98% PWM on that. I believe the
TCC duty %, more is more while on the force motor, more is
less modulated line pressure. Hope that's right; if not, might
explain some things
I talked to a tech at Art Carr. He said that the coverters they build are not designed for use with PWM (pulse with modulation). He said I have two choices. One, have my tuner go in and disable PWM. He said that this particular valve cycles so much during normal operation that it is measured in gigahertz. It is a hardened valve in an aluminum valve body and they also get worn. Second choice is to have the transmission builder remove it, bypass, whatever. He said something about replacing the spring with one from a 700R4...Any Comments
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
Originally Posted by Steve H.
I talked to a tech at Art Carr. He said that the coverters they build are not designed for use with PWM (pulse with modulation). He said I have two choices. One, have my tuner go in and disable PWM. He said that this particular valve cycles so much during normal operation that it is measured in gigahertz. It is a hardened valve in an aluminum valve body and they also get worn. Second choice is to have the transmission builder remove it, bypass, whatever. He said something about replacing the spring with one from a 700R4...Any Comments
i also have the full trans go kit in mine, it does the same thing that you are explaining except it locks then unlocks very quickly after its been sitting a while, i have a vigi. 2800 in mine, i replaced the TCC solenoid and it dodnt help any, any other ideas??
that "aluminum valve body steel valve" comment was already assessed by my post.
tcc lockup valve- the bore gets worn and lets fluid past it to the front of the lockup clutch, hence not allowing full/any lockup.. transgo has a replacement valve in their kit to fix the problem, unless the bore is too worn and then you have to drill it and go with a sonnax oversized valve.
try jimmyblue's force motor current tables (search on hptuners.com). your converter will lockup nice and firm and hold if the clutch is not already gone. i am currently running his tables in my car right now and like the firm lockup.
btw- if you don't have hptuners you are kind of **** outta luck, maybe try taking it back to your tuner...
tcc lockup valve- the bore gets worn and lets fluid past it to the front of the lockup clutch, hence not allowing full/any lockup.. transgo has a replacement valve in their kit to fix the problem, unless the bore is too worn and then you have to drill it and go with a sonnax oversized valve.
try jimmyblue's force motor current tables (search on hptuners.com). your converter will lockup nice and firm and hold if the clutch is not already gone. i am currently running his tables in my car right now and like the firm lockup.
btw- if you don't have hptuners you are kind of **** outta luck, maybe try taking it back to your tuner...
The tech is pulling your chain with the "GHz" remark.
And you can set the TCC PWM to be full on in the
programming if you want. But the real problem is, at
light cruise your force motor settings just leave the
TCC no pressure to work with, and little clutches need
more pressure than stock (multi-discs aside).
And you can set the TCC PWM to be full on in the
programming if you want. But the real problem is, at
light cruise your force motor settings just leave the
TCC no pressure to work with, and little clutches need
more pressure than stock (multi-discs aside).
