sfoltz

Just found this great site and have been doing a lot of research. I have a '99 RX300 with a approximately 63k. I have not had any problems until now . . . .

I read a lot in previous posts about how the transmission will not shift out of 3rd and into to overdrive until the car is warmed to a certain temperature. Mine is not shifting correctly even when warm. The transmission is NOT slipping, it just will not shift into overdrive on an intermittent basis. Sometimes it shifts normally. Temperature has no bearing on the problem. When the transmission does not shift into overdrive, it also then does not properly down shift if the accelerator is press down hard.

Could there be a bad sensor causing this? Would a clogged fuel filter cause this?

I also had an engine light on, but yesterday the rear FAR sensor replaced. The light was reset, but now its on again. The car did not shift correctly when I picked it up from the shop, but shifted correctly on one trip today and incorrectly on the trip home. VERY FRUSTRATING!

I have to have the vehicle serviced at an independent shop since I'm 3 hours from the nearest Lexus dealer. I will be taking it back to see what codes now come up.

Any help or suggestions are appreciated. BTW, this is my first post.

ederny

Interesting problem. This could be a difficult diagnosis. Perhaps there are a few tests to do before you take it in again.

If it is not shifting into O/D, I assume it is staying in 3rd gear. Can you confirm that by switching off O/D and see that there is no change and the trany is truly in 3rd gear. Can you then shift through the other gears normally (1st & 2nd)?

This could be something simple like an intermittent wire on a sensor or a big problem like an internal tranny problem. Hopefully your mech can get something out of the OBD code.

Good Luck!

sfoltz

ederny,

I appreciate your reply. To followup on your questions:

When its shifting incorrectly, it is staying in third gear. Pressing the O/D switch has no effect. Using the shifter, it manually shifts down to 2d and 1st. When stopped, it goes back down to 1st and shifts to 2d and then 3rd, but not to O/D. When cruising at 45 mph, for example, and pressing hard on the accelerator, it does not downshift correctly, but either hesitates and then shifts or stays in third.

When it is shifting correctly, everything works fine. The O/D button will take it out of overdrive and put it back in. All the above-listed symptoms go away.

On Friday the 24th, the car shifted fine all day during 8 to 10 trips (where the engine was shut off between trips) ranging from morning to early evening. However, on Saturday morning it did not shift into overdrive at 8:00 am and all the above-symptoms were present, but it worked correctly on the return trip at 10:00 am!

Would flushing the transmission be advisable? I get my RX serviced at the local Toyota dealer for major services, but I don't know if the transmission fluid has ever been changed, much less flushed, and if it has, whether the proper fluid was used.

Thanks.

CDN RX300

sfoltz,

I have a 99 RX as well, and had the exact same problem... except mine was staying in 3rd all the time. Took it to the dealer and they told me that one of the injectors was not firing, tricking the sensor into thinking the engine was still cold.

Not sure if this makes sense or not, but they covered it under warranty and it has been working fine for last two months.

Hope that helps.

ederny

Thanks for the detail. Not much to go on. So, there are many things that could be the problem. flushing transmission fluid wont hurt. The engine thinking it is cold, is a possibility - seems intermittent, so I wouldn't think it is a dirty/clogged injector ( the engine would be running a bit rough). If you think it might be an injector, try a bottle of Techron in the fuel tank.

If it was truly intermittent like a loose wire, the symptoms would come and go during a trip. Maybe someone else has had a similar experience who could help out here.

RX300TC

Just a few points:

1. Changing the Xmission fluid after a certain amount of miles is a good thing. In a few cases, fuid that has lost it's proper viscousity will cause shifting problems.

2. If you have a clogged fuel injector, store bought Techron won't do a thing for you. You see, there is a HUGE difference between the retail version of Techron and what a fuel injector cleaning system at an auto repair shop uses. The stuff the repair shop uses is so powerful they have to bypass the gas tank because it would eat at the protective coating inside of it. The store bought stuff is highly diluted and meant to be used as a PREVENTIVE measure, ie, stop the small buildup that occurs before it turns into a big clog.

3. In the end though, there is something wrong with your Rex. Taking potshots at the problem migth fix it... might not. I guarantee that your vehicles computer is putting out a trouble code. Any reputable repair shop will have a scan tool that will read that code, they simply then access their Mitchell or AllData system for the troubleshooting flow-chart they will correctly fix the problem without needless repairs.

Good luck,
TC

sfoltz

Thank you all for replying.

When I took my RX back to the mechanic, the codes that came up were "lean condition" on the rear bank and knock sensor. The mechanic believes the knock sensor (the car is pinging) is caused by the underlying condition lean condition and will go away once the other problem is fixed. He also thought a defective fuel injector could be the problem if its malfunctioning, but not totally dead. If the injector is partially clogged could that set off the code?

As I posted above, my RX has over 50K (out of general warranty) but under 70k miles on it. Would defective injectors be covered under the 70k drivetrain warranty? My mechanic said he could test the three injectors on the back, but did not want to begin the work if its under warranty.

Do you think its time to "bite the bullet" and take the car over to Jacksonville Lexus (I'm in Tallahassee)? Assuming its not under warranty, is this something a Toyota dealer should be able to fix?

Thanks.

ederny

Some Toyota dealers may work on your vehicle, call up and ask the service manager. They are familar with the engine as it is in the several Toyota vehicles.

I would also check with the Lexus dealer in Jacksonville if they consider injectors covered unter the drive train warrenty.

Let us know how you make out with this. Thanks.