jpvoid

Hi, i had problem with my RX300 gear shifting. When starting to drive, for initial 50 miles, the gear shifting was smooth. afterwards when the engine is hot, the vehicle was taking jerks in shifting from 2nd to 3rd gear. i used the car for till 130k just like that. finally one day the vehicle totally stopped to shiftgear beyong 2nd gear. Only 1st & 2nd gear worked.
I got new transaxel & torque converter fitted with dealer.
Now i am back to old problem again- hesitation in shifting from 2nd to 3rd gear.
Dealer tells me that it may be due to weak engine!!!! and old exhaust system??
I do not understand, how come engine or exhaust system lead to such gear shift problem. Kindly guide me

jpvoid

There was no error code anytime, also no check light ever.

Lexmex

Welcome to the Club. My parents now live in Washington, DC and I also went to school there (I am a Hoya), so a very special welcome.

Hesitations after these repairs usually come down to electrical grounding not being reconnected right or not enough fluid in the transmission.

Now, the exhaust system can lead to a hesitation issue if there is a leak (usually occurs in junction sections held together by bolts (14mm). I see those near the catalytic converter underneath the vehicle, and can be due to a frayed gasket.

I am not sure if you have an AWD or FWD, but if you have an AWD, the transfer case and/or rear differential having old gear fluid (transfer case holds about 1 quart and also the rear differential holds the same amount, respectively) can lead to a delay between certain upper gears (notably the 2nd to 3rd), but usually it's a longer changeover and not a hesitation or jerk.

Don't expect a code either, it would rarely if ever occur unless there was a very visible issue with the exhaust.

Only thing offhand I could see with a weak engine would be some wear around the piston rings, but that's still young for that to occur and it wouldn't happen suddenly.

ecoastkid

I find either of those explanations by the dealer to be umm....hogwash.

Check your fluid level first thing.

My race truck (not a lexus or toy but the thought process is the same) barks the tires at part throttle on the 1-2 shift and suddenly that started being intermitant and even soft at times. Also started to shift really slow oin the 2-3. I figured the trans was done so I had my buddy bust out his megga dollar snap on diag stuff and after running a battery of tests and us test driving it, he said "did you check the fluid level"...Of course I had not..lol...its was only 1/2 quart low. Embarising but a good lesson either way..lol

I'm pretty certain these are electronically shifted transmissions, did they reuse the soleinod packs on the new transmission or replace them as well. Could be a stuck or slow moving one.

jpvoid

Thanks Pal. I am a new member and surprised to find it sooooo active.

It is RX300 AWD 2002.

Exhaust system seems OK. no leak. no warning signals. visually looks intact without rusting.

Transmission fluid levels is OK (it is new).

Regarding reuse of the solenoid pack on the new transmission , i need to ask them!

The engine is old and so is the hesitation problem. It did not crop suddenly. Can it be due to weak engine then?

What about ECU for transmission state. Can it go wrong without ECL coming up?

I found engine idling rpm on higher side. it is 750 rpm when in neutral gear. is it ok? I think before repairs it was lower.

Lexmex

750rpm is normal. The main thing that can affect that rpm level is something called the iacv valve. If you are seeing any bounce in the rpm when the vehicle is not in motion, then that would be where I would put my finger on, but that's not the case.

ECU is usually the last thing on the list, and it's extremely rare those things will foul up on their own.

If it were a weak engine, then the rest of the gears would be affected, not just 2nd to 3rd.

The exhaust issue is not something that will be clearly visible. It can be right near the joints and you'd have to place your hand underneath at a distance to feel the heat. Rust is not the sign to look for.

jpvoid

The gear shift problem from 2nd to 3rd is in detail:

Up to 2nd gear the change is normal. After 2nd when the throttle is pressed more then the gear doesn't shift upwards till much higher rpm (3500-4000 rpm) then with hesitation it goes to 3rd gear and engine rpm comes down to 2500-2750 for 50mph speed. downward shift does not have any hesitation.
most important, when engine is cold, the gear shifting is very much smooth. The problem aggravates after driving for sometime.

Problem was already there before transaxel change. I always thought and mechanics told me that this problem is related to Tranny. but i found that it is something else (after a deep hole in pocket).

jpvoid

checked all the exhaust joints. no leakage anywhere.

jpvoid

On stopping at traffic light and coming to neutral, the rpm first howers at 1000 then comes down to 750.

ecoastkid

The transmissions do not come with fluid in them so it gets filled after the install. It can be a pita because you need to keep putting some in, cycling the gears, checking.....repeat. Its very possible to be low on fluid.

I'm at a total loss as to how a tiny exhaust leak would affect your shifting performance. I've never heard of such a thing.

RPM flux when going from d to n or to d with a/c is normal. That is individually configurable by each state the ecu finds things in.

jpvoid

since problem increases with temperature, can it be due to some sensor. like water temperature sensor connected to ECU.

ecoastkid

are you shifting it into neutral?

ecoastkid

You would likely throw an out of range code for that sensor..I doubt its anything like that.

The transmission itself will act differently based on its own fluid temp (which you dont have guage for unless you added one.

Also, the ecu will command the trans to do different things based on temp. Many people complain about their transmissions not wanting to go into over drive when its cold until it warms pu but often that the ecu not allowing the converter to lock.

jpvoid

I will get info about solenoids (if they r old or new) from dealer and come back for advice.

Do you have data regarding standard setting for gear shift w.r.to. vehicle speed for RX300.

jpvoid

yes i do shift to neutral. otherwise with brakes rpm is 1000