Is it ok to lock up the torque converter on a dyno? (A340E)

I mainly work on traditional MT or dual clutch transmission but have recently taken up a project on a Supra A80 with a stock A340E automatic transmission.

I know locking up the torque converter while under high load when the torque already slipping is a big no. But is it ok to lock up the torque converter under minimal load first then apply power while keeping it locked?

Is it the abrupt locking under load that causes damage or is it simply the torque converter cannot handle high torque while locked up?

Thank you.

I'm not an auto' guy, so take this under advisement, but I would expect locked up would be better to reduce the transmission temperatures and increase accuracy because the torque converter isn't slipping.

I would hope some of the auto' chaps will chip in to clarify this.

The lockup clutch is very small in size. Its purpouse is to get rid of the rpm difference between the two "wheels" (pump & turbine) inside the TC under steady state conditions. This yields to a small improvement in fuel consumption and emissions.

Having said this, the lockup clutch is only capable of holding very small torque.

Depends on the torque convertor and power output really. If it doesn't slip it should be fine. I do it quite often on GM LS cars.

Yes I just looked up images of lock up clutch for the A340E and they are just a few small thin rings. So I guess in the case of A340E they really cannot take much torque at all.

I might try to lock up the torque converter under low loads for steady state tuning VERY carefully and let go of the throttle IMMEDIATELY upon any signs of slippage. The clutch does look very fragile though and I am kindna worried that it would burn under slightest slip when under power.

WOT pull is definately a no I guess.