Kickdown Fail

[grandpa_spec98]

So I took the old LS400 (98) for a joyride today, and to my surprise, at full throttle it falls flat on its face. At least 4 seconds before it decides to kickdown. I know the transmissions are electronically controlled, but is there a way to make the kickdown more responsive at all?

Edited November 16, 2021 by grandpa_spec98

[Jeremy M.]

I can't promise a fix for a slow downshift because I'm not 100% if it applies to the LS400, but some systems use inputs from both the TPS and MAF, so cleaning out your filter and spraying down your MAF (with the proper cleaner) might help a bit. Even in my 98, there was some delay, so I doubt it would be gone completely with that, but it should only take a second or two instead of four.

Edited November 19, 2021 by Jeremy M.
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[paulo57509]

Which downshift is slow?

OD-->4th, 4th --> 3rd, 3rd --> 2nd, 2nd -->1st?

[grandpa_spec98]

I think it is all kickdowns but I was in third and the kickdown to first was sickeningly slow.

[paulo57509]

If it's all of them I would think it's the input to the ECU that tells it what the throttle is doing and not the transmission itself (shift solenoids); what Jeremy is saying.

The A650E seems to occasionally have issues with slow TCC release.  Perhaps that's what is causing the slow downshift?

https://transgo.com/product-details/toyota-lexus-a650e-shift-kit/

I would look at other things before tearing into the valve body.