94GS300

Alright, I have seen quite a few posts for a number of different cars in here that seem to have the same problem I have, or at least I think they do. I have a 94 GS300. The problem is when the car is first started when it is cold outside (below 30F). I let the engine warm up for about 20-30 seconds and then put it into Drive and drive very slowly to take it easy on it. Basically I have the throttle at maybe 5-10% at the most and it will shift to 2nd and everything is fine. When I get to the first street where some slight acceleration is needed, the engine rpm's climb sky high in 1st gear, but the car barely moves. It does this for about 5-10 seconds before it shifts to 2nd and then the problem never comes back. This is so bad that it is very dangerous because people almost rear-end you.

In order for the rpm's to climb and the vehicle not go as fast as it should in 1st gear (correct speed ratio), one of two things must be happening:

1) The transmission is slipping one of the clutches
2) The torque converter does not have enough fluid in it

A lot of people are claiming that the computer is doing this to warm up the fluid faster, but I find that hard to believe. I need to get a schematic of the transmission controls, but the only way the transmission controller would be able to change the speed ratio (output speed/input speed) would be to back off line pressure which would make a clutch slip or cut off fluid to the torque converter. The controller would do neither of these things because it would not reduce line pressure and risk slipping a clutch in 1st gear and it would not cut off fluid to the torque converter because the torque converter is what causes the transmission fluid to warm up.

Any Lexus technicians or anyone else have a good explanation for what is happening? I personally think I am slipping a clutch when the fluid is very cold because either a valve is not opening all the way, a solenoid is not producing enough pressure, or I some debris in an orifice (not likely since the fluid pressure would blow it out). If this was the case though, then all these other people complaining about this would have slipping clutches and we would here more about these incidents.

I have done all the obvious things: fluid level is correct with fairly new fluid and I cleaned the metal filter screen.

Anyone want to take a stab at this?

mojofilter

I experience the exact same thing but with a 98 gs400, but only on that first gear shift, after that it never happens again. which makes me think that if several people have it, it's either something built in, or some sort of design flaw. or, and also quite possibly the case, my car is broken.

the sheer contrast between the 1rst time i go into 2nd every day and the next time, which i might add is less than 10 seconds later because of a stoplight, makes me think it's something built in. Because the engine hasn't heated up yet at all, and certainly not in the 20 seconds between going from 1-2 to stop then 1-2 again. On that second shift though and every subsequent shift, I would say it comes out of 1rst 500-1000 RPMs lower. I will verify it tommorow, and it's always the same, but only when it's cold out.

94GS300

mojofilter,

Is your car just holding 1st gear longer before going to 2nd, or is the engine increasing in speed but the vehicle barely moves any faster to the point where it is dangerous? Sometimes it is so bad that the engine could be doing over 3000rpm and the vehicle will only be going about 5 mph.

mooretorque

94GS, I posted a reply to this thread over on the GS forum, before it got moved; if this is a repeat, pls excuse.

I've not experienced the shift delay in the GS but in my wife's RX, when cold, the tranny will hold 3rd until the trans fluid temp comes up to about 180 F. But it accelerates normally. Yours is definitely slip.

I agree with your analysis of possible sources; I think you're going to have a visit with the transmission doctor soon..........

mojofilter

I think I misread you original post, it accelerates normally, it just changes gears at a higher RPM. It changes at around 20-25 mph at 2500 RPM, from there on out at about 2000 RPM. Sorry I couldn't be of more assistance.