93 Lexus With Shifting Problems

[Lexygirl88]

I bought a 1993 ES 300 a year ago. The car ran perfectly for about 6 months now it doesn't run so great.

When the problem first started I would loose power only on the first left turn I would take. It would act like my gas pedal wasn't hooked up, and once in a while it would just die. But after I got around the corner or restarted it, it would be fine.

Then it started to not have any power on the first take off and some slow shifting onto first and second gear. But after it shifted it would be fine. The rest of the day.

Now it has several issues.

1. There is very little power at take off (won't go over 10 mph if your lucky enough to get it there)

2. It backfires within the first 30 seconds of driving it (sounds like it's coming from under the passenger seat) but it only backfires once when u first start driving it.

3. It doesn't want to shift, it takes forever. When it does shift it is very hard.

4. On the freeway it is very slow to get up to speed and once you hit 60 it down shifts and won't go any faster. However if you can get it to go to 80 it's fine at 80 just not at 60-75 MPH.

5. At every stop the shifting problem starts over until you have been driving for 20-30 min.

We have had the tranny looked at and told it was practically brand new. My husband replaced the tranny sensors and some other relay sensors. But it hasn't fixed the problem. If you disconnect the battery long enough to clear the computer it will run perfectly for a day or two, then it will start all over. Any ideas what this problem is?

Thanks!

[gbhrps]

lexygirl88,

Your generation of Lexus doesn't have the OBDII port for scanning the computer for trouble codes, as all cars from 1996 on must have. The code reader will tell the mechanic which system has the problem, and where to start to find a solution.

On your car, I believe the same type of thing is available, but is done by recording the number of light flashes, and their sequence, as found on the car's computer, when the car is put into its diagnostic state.

You need to locate the engine computer (ECU), somewhere under a seat, under a plate on the firewall inside the car, or in the engine compartment. It will have two or more LED lights, that when the car is put into its diagnostic procedure, they will flash. For instance, if the left one flashes twice and the right one three times and then pauses, the code is 23. 23 can refer to perhaps a bad ignition coil, as an example. One of my toys, a 1990 Nissan 300ZX has just this kind of system.

Anyway, the point I'm trying to make is don't spend any dollars throwing parts at the car trying to fix what you think is the transmission, when in fact the problem may be with the throttle position sensor, which also triggers the transmission, as well as the engine speed. There may not be any problem with your transmission, because the tranny won't make the car backfire.

Take your car to a good independent mechanic who works on Toyota's, Honda's and most all makes. You don't need to go to Lexus dealership and pay big labour rates. He'll have the reference materials needed to put the computer into its diagnostic setting, find the codes (there may be several) and tell you what's needed to get it running properly.

There are so many electronics on today's cars, that scanning the computer is the only way to track down all of the systems that feed each other and impact its performance. Bite the bullet, and take the car to someone who knows what they are doing. Good Luck!

[Lexygirl88]

Thank you. The check engine light isn't on and has never came on with this issue. I had the code read just incase there was something there and it just kept flashing continuously. Not sure what that means.

[gbhrps]

Lexygirl88,

As I suggested, don't throw parts at it. Get a good mechanic to diagnose the issue. It'll save you money in the long run.