bbambrough

My 99 RX300 has difficulty shifting into the higher gears when I first start out on cold mornings. The engine will go up to 3,000 - 3,5000 RPM + and hold for a quite a while (mile or two) before shifting. It will go through this routine for each gear until it finally warms up (5 - 10 min.). It seems to shift fine after it warms up and the rest of the day. I'd appreciate any advice, tips or recommendations on this. Here's what I know about the transmission and possible issues so far. I've only had the car a couple of months. The transmission level is to the top mark (checked level running and hot). It was down a quart, but its at level now. The transmission fluid and filter was replaced by a Lexus dealer about 30,000 - 40,000 miles ago (car fax report). I'm not sure if it was flushed or not. The car has 234K miles on it.

I don't know if this would effect the shifting, but I believe I the thermostat needs to be replaced. The engine temperature stays on the lowest level or the mark below the normal. If the car ideals for a while, the temperature will reach the normal mark.

Any advice? Is this something that can be corrected? Could this be an early signs that the transmission is going?

LeX2K

Go to a Toyota or Lexus dealer and get a thermostat. Overdrive will not engage when the engine is cold this is normal and by design. IMO your transmission is due for another service.

bbambrough

I'm having difficulty believing this is related to the thermostat. In the winter months here in Utah, all of my other cars with automatic transmissions will shift normally through the gears well before the needle on the temperature gauge will starts to rise.

salimshah

Neither do I, but it still makes sense to verify the fluid level. The transmission fluid volume changes substantially with temperature.

The other thing is the known behavior of RX .. locking out the O/D till things warm up and not necessarily all the way to normal operating temperature. Then again don't count on engine warm up and thermal distribution by convection + radiation from the engine to the transmission to heat the transmission. Ten minutes of driving should do it [again causing does not help much .. heat is generated when the hydraulic clutch is slipping/operating .. shifting].

Once you past these, then we really need to look at the OBDII data to understand what the ECU is trying to do.

Salim

PS: Why the link to engine temperature? What I have heard is that it was done to help to reduce time to get to the optimum operating temperature [make the engine work harder] and that would reduce pollution.

bordenj66

I was under the impression that OD lockouts are generally to protect the transmission from the engine since the gear ratio is larger than 1. Hence bad knock sensors also lock out the OD. On cold start you have relatively poor and variable combustion that could impact the transmission?

bbambrough

This is all good information, but I need to point out that this delated shifting in cold weather is not normal in any way. Prior to this 99 RX, I had a 99 Toyota Sienna. It always shifted fine in cold mornings, even sub zero mornings. My wife's 2013 Honda CRV shift perfect on cold mornings.

There are some mornings with the Lexus that I'm not sure its going to shift into the next higher gear. I'll take the RPM up as high as I dare and then down again trying to get it to shift. Thanks again for all the input.

salimshah

ECU can prevent getting into OD for various reasons ... you mentioned Knock sensor problem as one. Generally referred as 'limp mode'. But they are coupled with CEL [Then again all CEL conditions do not put the vehicle in limp mode].
In cold starts, the vehicle is configured to get to operating conditions as fast as possible.


Salim

Nate99RX

I have this same issue with my 99 Rx300! In colder weather I have to wait for the engine to fully warm up before I drive otherwise I can’t get passed 2nd gear. Just won’t shift. I also notice as I drive the temp gage will drop back to cold (I assume somehow from the cold air) - I can sometimes get past this issue by VERY slowly increasing my speed as I get on the highway but that can be dangerous and shouldn’t have to do that.
Anyone who has had this issue your advice is much appreciated.

Nate99RX

Same! I have the exact issue and confirm this isn’t normal at all. I’ve had numerous vehicles and this is the first to ever have the temperature gage Drop back down to cold after it’s fully warmed up and have been driving…..

salimshah

Cold is relative term but inn general start by checking coolant level [make sure the system has no air ,,, this happens after coolant is removed and refilled]. For observation, try by not tuning on the cabin heat .. and you should see progressive climbing of the temp gauge. Once it moved up from the bottom peg try driving out. If the gauge starts falling down, the thermostat may be bad [the thermostat should remain closed to allow the block to get warmed up] and only when the desired temp is reached it opens up shortly to allow colder coolant to enter and then shuts off]. {Reminds me of my mother in law's car, she was happy that her vehicle is not heating up :^)}

Salim

Nate99RX

thanks I’ll look into this!

Fit1too

That's what our RAV4 was doing, I had the dealer change the water pump and they did the thermostat at the same time. They used an aftermarket thermostat and it would heat up like normal, then cool down once I was on the road. Prior to that, it ALWAYS stayed on the half way mark, NEVER varied. Like Salim, I'd say your thermostat is bad. I had an OEM unit sent to me and replaced it myself. All was well after that.

bbambrough

I have a habit of watching our classified ads for 99-2002 Lexus RX300 I've noticed there have been quite a few sellers over the months trying to dump their cars for parts and ext. because the transmissions have goon out There are two in out classified right now. My questions are, 1) do RX300 during these years tend to have transmission failures. and 2) could the cold shifting be an early indication that the transmission is going out? Thanks

bbambrough

OK, I'll replace the thermostat to see if that works. Still doesn't make much since to me, because my other vehicles would smoothly sift through the gears long below the gauge would start to rise. But, may Luxus is different Thanks

Fit1too

The transmission in the 1st generation RX300 and Toyota Highlander do seem to get a lot of discussion. Mine does hesitate to shift after the car has sat overnight—even in the summer. In the summer I give it a minute or two and then back out of the drive and head out. I take it easy until the end of our street. The Interstate is a good mile and a half from my house, so by then it goes thru all the gears fine.

Mine acts funny downshifting as well i.e. when turning onto my street from about 5-10 miles per hour. I have to let it do its own thing i.e. let it shift into first gear and then press the gas pedal. If not, it will jerk (slam) when it downshifts into first. It’s been doing this since I purchased it two years ago, and I’ve put 50K plus miles on in the meantime. The transmission fluid and filter have been changed three times, once by the previous owner, twice by me. I’m at 144,000 currently—mine is FWD.

I can take off from a standing start at near WOT and it will shift perfectly. I can enter the freeway at WOT and it does beautifully. I can floor it to pass a car on a two-lane, and it performs fine. When we travel for my wife’s work, the RX is packed with equipment, books, luggage etc., and it has proven to be a fine workhorse—though I do take it easy when it’s loaded like that.

This is the way I see it. My RX is going to be 22 years old this year and it is pushing 150K miles. I take it easy on it as much as possible, especially when I first start out in the morning or it has set overnight. I know it’s frowned upon, but I let my vehicles warm up for a good five minutes or more in the winter. Like I said before, I’ve learned to let it do its thing down shifting when I’m turning onto my street or similar situations.