Hi all,

Just wondering whether it's normal or not for the gearbox to slip a little when putting your foot down lightly, not enough to make it down change?

Basically if you're cruising at 50mph then press the throttle the revs will climb say 500rpm, let off and they'll drop down, press the throttle again and they'll rise 500 rpm. I'm guessing this is just a general trait of a torque converter?

Car has done really low miles so can't imagine anything is worn.

 

There is a subtle rise in RPM's from the torque converter slip when it's not locked, but I don't think my car goes up by anything close to 500rpm. That's a lot.

That being said, if you're in top gear and put your foot down, the TC will unlock and the RPM's will rise by about that amount, almost as if it downshifted. I don't know off the top of my head if the car has a locking torque converter in anything other than top gear.

It's one of the most rare parts to fail on a transmission. You'll get a " shutter" when leaving/taking off from a stop. Have you noticed any other drivability problems?

 

Thanks for the reply.

It selects gears fine although does grab a bit when selecting drive or reverse with the brake on, pulls away fine, changes smoothly when it should. I just wondered whether there should be a slight rise in revs. If I let off completely and then press the throttle it also rises / feels like it slips a little, so I would assume its pretty normal, but wanted to make sure. ATF Oil level is good when hot, but appears high when cold.

 

I dunno, go watch some POV drives of other cars and see if yours behaves any differently.

https://www.youtube.com/results?search_query=ls400+pov

Selecting Drive\Reverse sounds normal when torque is applied to the driveline.

And yes, the engine does "surge" in rpm a little bit if you hit the throttle light enough to stay in the current gear. Depending on what revs and what gear and what speed I get a couple hundred RPM out of my car.

You say +500rpm at 50mph. Are you sure it isn't the torque converter unlocking? Because the car should be in 5th gear at like 1500rpm if you're just cruising, TC locked up. The TC should unlock first, then it should kick down into 4th.

 

I've watched a couple of videos and it does seem similar.

​​​​​​Mine is only a 4 speed gearbox, it does it in 3rd and 4th gear that I've tried. Without kicking down to the lower gear.

When flooring it, it doesn't slip or continue to slip like a worn gearbox would indicate. It holds the revs and increases with speed as normal.

I watched a video on YouTube and his seemed to increase in revs by about 400rpm on a 1999 so would've been a 5 speed. There aren't many videos looking at the dash when driving.

 

I mean if you floor it the revs will increase by a lot as the transmission downshifts. My earlier comments were about very light throttle inputs that weren't enough to get the gearbox to downshift.

 

Thanks, I appreciate the replies.

​​​Pretty sure it's just the way automatic gearboxes are.

I know if I'm cruising and then let off the throttle completely the revs drop as expected. Then when you press the throttle again they'll go up and slightly over where they were when cruising.

​​​​​​With light inputs when cruising it doesn't do it quite as much as I thought it did. More like 2-300rpm. Sometimes it doesn't do it at all.

 

Early LS 400 Engine Control Units (ECU) controlled both the engine and transmission.
Some shift problems are solved by replacing the electrolytic capacitors in those cars' ECUs. These capacitors contain liquid electrolyte and after many years this slowly leaks out, changing the performance of the ECU.
The subject is dealt with in this lengthy but excellent thread on this forum:

https://www.clublexus.com/forums/ls-...ium=ForumLinks

Some contributors there say their cars' shifting performance improved after the capacitor replacement.

 

Thanks, I've had a good read of that previously. So it's probably on the list of things I'll need to change. But I don't appear to have any of the symptoms of bad capacitors.

My car is a 1996 toyota celsior and it has the 89661-50380 ecu which is the better one to have apparently.

 

Does your ECU # use different brand and type of capacitors?

 

From what I've read that ECU number doesn't have the engine idle problem after cruising, where it stalls when you come to a stop / junction.

Still has the same type of electrolytic capacitors.

 

I had an issue on my 97' with the lockup solenoid for the TC. The car would shudder when coming to a stop and took awhile for the converter to unlock when at a stop. I eventually replaced the lockup solenoid with a JY one as a test and it solved the problem. P0770 was the CEL code thrown. A new lockup solenoid from Lexus is $300.