Question about 1998 Toyota Corolla
Hi. I have a Toyota Corolla (it has 110K miles on it, I'm the second owner of this car but I used it 3 years without any problem before this problem).
The problem seems that car can't decide which gear is the appropriate gear to use for its speed... When it is in the 2nd gear and when it is time to go to 3rd, it stays in the 2nd until RPM goes really high, when I take my foot off the gas pedal it switches to 3rd but when I accelerate it immediately goes back to 2nd (and after this check engine light goes on). Sometimes it even goes back to the first gear which makes the RPM go all the way up to 5-6K if I put my foot on gas. Or for example if I'm going with 60-65 and if I stop accelerating the car, RPM first goes down but then starts changing gears by itself as if it briefly visits all gears available (I can see how RPM moves back and forth to different small values and shakes the car (it shakes quite fragile though, as if you touched to the break very briefly and lightly)). And when I put my foot on gas pedal I find the car in, e.g., second gear doesn't matter how fast actually I go and how wrong it is for the car to be in the 2nd gear for that speed.
The worst part is the problem comes and goes. Sometimes it works perfectly, check engine light goes off and everything works smooth for a day or so. Then it happens again.
This problem first appeared 1 year ago (I can't think of anything that happened before the incident which may have caused it). Check engine light was on for the first time. I went to a mechanic and he told me that according to the error code there was a problem with Vehicle Speed Sensor. I paid $200 and he changed it, but the problem didn't go away. Then he said "oh now we need to change something in the transmission because you burnt it, it is gonna be another $1600 for you". I realized that he didn't exactly know what was wrong and didn't let him do anything else. After a couple of weeks the problem was gone all by itself and it didn't happen again until the last week.
My wife thinks that hot weather might have something to do with it. Because it never happened during the last winter and as soon as weather got hot again it started to happen (We live in New Orleans and weather gets too hot here :)). But I think it might just be a coincidence since everything around the engine gets too hot all the time anyway. But of course I'm not sure.
I don't think it is a mechanical problem because it is not consistent. Also it is sometimes manageable, sometimes not. I did a little research and I read that throttle position sensor or catalytic converter might have something to do with the problem. But I have no idea and don't want to be overcharged by dishonest mechanics again :(
I would greatly appreciate any kind of help.
Thanks in advance.
HI.this is not as major as you may think. there is a transmission control module that sends commands to the shift solenoids that are located inside the transmission pan. If the TCM is damaged, it will not send the correct shift signal to the solenoids, in return, causing these erratic shift patterns you are experiencing at this time. This is not a mechanical issue at all. its mostly electrical.
I recommend replacing the Transmission control and the shift solenoids as well. i would also recommend a total transmission filter change and flushing of the internals as well. this will fix the entire issue.
Concerning the catalytic and throttle position sensor, these malfunctions will be noticeable by error codes given to you or your mechanic, via diagnostic scan. if the check engine light comes on, run a diagnostic scan. this will bring up the proper codes for the cat and the throttle sensor. if these two codes don't register, this will rule out any issues with the catalytic and throttle sensor.
NOTE--- If by any chance during the flushing, you or your mechanic notice small metal fragment in the fluid and on the bottom of the transmission pan, this will confirm major gear friction and damage. In this case, i would recommend a total rebuild of this transmission. the metal fragment drops will be a bad sign of gear pack trauma.
Posted on May 23, 2009
Hi, it does sound like there is some internal damage in the transmission, even tho it only happens sometimes, there are a million different parts in a transmission, if one or more is burnt up or cracked it may only act up sometimes.it could also just be the valve body but chances are if it has been doing it on and off for a year, you have probably done internal damage. most shop will just quote you for a new or used trans. because it usually cost more to rebuild that to just replace the tranny. this is because the transmission has to come out of the vehicle either way. it may be a good idea just to replace the trans. before the high rpm's take toll on the engine. with out being there to look the vehicle over i can't say that the trans is not junk but it sounds to me from what youv'e said that it should be replaced. i know it can be costly for diagnosis, but it is probably cheaper than an engine and trans. i would say that your local toyota dealer would probably be the best and the quickest place to have it diagnosed the right way. if it's just a valve body repairs are usually around $500 depending on the cost of the body itself. You should probably not drive the car when it acts up to save your engine. heat does have some effect on the trans., but it shouldn't be enough to notice a change. hope this helps you some and good luck!!!
Posted on May 22, 2009
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Posted on Jan 02, 2017
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