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(No prizes for guessing I'm back at trying to nut out my TCC settings... and finding more questions than answers ;) )
Can a Torque Converter "lock" itself once up past its hi-stall speed?
Edit... I'm not talking about PCM requests here, the converter itself. Yes, I am clutching at straws here...
I believe there are some TCs that have a special
positive-locking clutch that will grab on very high
torque & RPM, but I think these are pretty rare and
you'd have to ask for it special. ???
There was nothing special requested with my TC, so I can probably discount that then.
I'm going to have to go and do more data logging - I don't seem to be able to trust what I am feeling on the road.
What brand / model of converter? What to look for
is something on the manufacturer's sales site /
literature about "positive lockup clutch" or something
like that. But the only ones I've seen like that are
some more "extreme" models.
It is a custom Pro-converter - basically a standard converter rebuilt by a local Melbourne company, to the additional specs of my transmission guy. The standard converter is rated at about 1800. This is rated at 2200-2500. On my car, it is around 2550.
The issue I have is on light load, 0 - 30% TPS. Again and again I see the following..
. 63km/h - 3 - 4 shift as expected
. ~69km/h - TC soft locks (unexpected)
. ~76km/h - TC hard locks (expected, but only if soft lock has released)
By soft lock - if I change TPS at all, it instantly unlocks. So lift off accelerator, unlocks. Apply an extra 1% TPS, unlocks. Once it hits 76km/h it locks and holds it as expected. If I hold the same TPS and it goes past 76km/h, it simply remains locked.
I was having hellish trouble with bizarre behaviour, so set the lock point in 4th at 76km/h, for all TPS under 31.25%. The phantom lock then became obvious. As I said, it is consistent.
Hence my question above. I was down to thinking the convertor was doing it, that VCM Suite had a bug, there were more parameters VCM Suite didn't access yet, or there was a bug in the PCM software. (The fact the soft lock is released on any TPS change hints that it could be the case.)
Having said that, at least it is consistent, and the current trans cal is about the best it has ever been.
Hi Elmis,
This sounds very similar to the issue im having with a 4000rpm converter. I was thinking that it may be the TCC duty cycle (PWM) partially releasing the TCC at 0% TPS. Might look at making it more agressive to see if it corrects the problem (the TCC apply pressure has already been increased mechanically).
Quote:
Originally Posted by Elmis
Yeah guys I have this issue as well. 12202088 OS, 8.1L 4L80E trans.
If I put the stock calibration back in it still does it, but I don't notice it with the soft TCC apply pressures.
It's one of two thing. There may be a TCC slip test in 4th under light throttle or there is a bug in that OS.
The 12202088 OS was relaced for numerous bug issues with the 12208322 OS. Between the two not one bit in the calibration was changed, only numerous code fixes.
As it does it with the stock calibration, but I only notice it with increased TCC apply rates I put it on the back burner of things to do. I have not upgraded to the newer OS.
What OS are you guys running?
Ken
How do you tell what Op sys you are using? I have an Op Sys id of 9381344?
You mention soft TCC apply pressures - how do you change that?
Elmis,
On the OS#, it tells you on the flash file info window.
On yours, adjust your trans component slipping test temps if you don't want them to occur.
For the TCC pressure, set your TCC offset table values higher.
Ken
Then my Op Sys is 9381344.
It is helpful knowing I am not the only person experiencing this.