transmission Lexus es300 Trans Shift Issues In Cold Tempertures

[BeetleJuiceDNL]

I just wanted to say before i continue, I'm 21, Female and this is my first car I've owned for about 3 years ( not that any of this is really important)I'm starting to want to learn more about cars and how to fix my own problems and save money instead of relying on a mechanic. So far I have repaired my busted front bumper, repaired and replaced R headlight housing and bulb, and Replaced an 02 censor.

I'm having issues with my transmission shifting gears in cold weather, but it runs like a dream in the summer. This was a problem last winter but wasn't as bad. Before, while accelerating and merging over on high-way, it wouldn't use the 4th gear at first but then it would shift gears after driving for a bit. Does the same problem now, but won't change gears at all or takes 10 mins+ to shift itself. sometimes has issues shifting 2nd gear to 3rd.

 es300 is 206xxx miles, 1999 model, and the transmission was rebuilt July 2016. I'm afraid this might have something to do with the previous failing but i want to try and fix the issue myself but can't figure out why this is happening or where to start. Coolant meter is always where it should be, oil is changed religiously, 02 sensor bank 1 sensor 2 needs to be replaced.

 4000 rmp at 75mph... (o/d drive is not on). Sometimes when braking hard or getting off high way, doesn't accelerate as it should, almost as if it skips 2nd gear. Accelerating 1st to 2nd at stops goes back to normal if I restart engine. 

Over all, why is this happening and how can I fix it? Only happens during cold temperatures below 40.

[gbhrps]

BeetleJuiceDNL,

 

I applaud you for wanting to learn, and for tackling your own automotive issues. Too many women, ... and a lot of men, just turn the key, and if the car doesn't start ... they throw up their hands, go to the dealership .. and get taken for a ride on simple issues they could solve themselves, if they'd taken the time to do some research.

I've been wrenching on my own cars for 55 years or so, and do all of my own mechanics ... when possible. But I recognize that there are some things that even I won't try tackling, because I don't have the expertise.

In your case, I think you have an issue that only a a decent mechanic can diagnose and correct, because there are too many variables. First off, any good independent mechanic should be able to get to the bottom of the problem. If he has worked on a Toyota Camry, he can fix your Lexus. You don't need a Lexus dealership and their high labour costs to do it.

It is possible that your transmission needs a software reflash, or that in that tranny rebuild some of the shift solenoids were deemed good, and weren't replaced, but are now sticking or have gone south. I suggest that you have your codes read from the OBD2 port, to see if any tranny codes show up, even though your check engine dash light hasn't come on to indicate one. You might also check to see if your tranny fluid level is low. Remember to check it at idle after the motor has warmed up to get an accurate reading.

One other thing you might try is to disconnect the battery for a half hour to kill the engine computer memory, then reattach it. The computer will then relearn your driving style over the next hundred miles or so, and if the car is driven aggressively, may remap your tranny shift points, etc., and correct some of your problems. There is no guarantee, but its worth a try. Good Luck and keep us posted.

[Edaphos]

I hope that you are still following this post.

I recently spent a winter in Minnesota where evening temperatures occasionally fell below -30F. I had the same problem that you described, exceptionally high RPM  before shifting - versus good shifting under normal sunny summer day conditions. First, my 2000 Lexus ES300 has about 180000 miles on the OD, only drained transmission oil when changing CV axles, so my transmission fluids were never completely changed (owner's manual recommends changing after 150000 miles if exceptional/under heavy use - e.g., heavy loads on long trips, only city stop/go driving, etc.). 

My observations. Given the age of my car and the miles on the OD, I decided try Lucas Automatic Transmission Fluid for high mileage cars. I did notice a difference - smoother shifting, better mileage (went from about 18 to 21 MPG city driving, and from 29 to 31 MPG highway. I was happy. 

Then I drove from Texas to Minnesota. This is where I found that the high viscosity Lucas lubricant really had a negative impact - when temperatures fell below about 10F. I learned through trial and error that warming up my car in the driveway for over thirty minutes was necessary to drive two miles (yes, I am an idiot) to drop my wife at work - necessary in order to warm the transmission so that it could shift from gear to gear in a more normal manner.

After winter passed, I found that the old transmission may have suffered some damage (after 4 months of short trips in freezing weather and two 1200 mile trips in below zero temperatures). I opted to have the transmission flushed. About 150 miles after the flush, I noticed a slight stutter when shifting from 2nd to 3rd and driving up a slight incline. Being a fan of proven liquid mechanics, I added six ounces of LubeGuard (red box). This product appeared to resolve the stutter, and improved shift points back to a good state.

While diagnosing and reading about all of this, I found a website that provides performance specifications (and more) for many cars including my year/make/model. I compared MPH/RPM data from my car to the MPH/RPM specs provided at the website and found a near exact match. So, despite the harsh diving conditions that I imposed on my car, it apparently survived. In any event, I have decided to flush the transmission fluid one more time, and yes I will probably have to add a high-mileage additive again. 

And by the way, I also perform nearly all of the repairs on my car in my garage, e.g., replaced entire suspension, timing belt/water pump, valve cover gaskets, spark plugs, fuel injectors, brakes, etc. - where the most difficult challenge for me so far was changing the high pressure power steering line, just excruciatingly tedious - but very doable. Next tasks are rack and pinion, and motor/transmission mounts. All good. 

I hope that you worked out your transmission issues without having to pay too much for professional help - WHT