Dear Lexus Owners

I have a 93 ES300 (150k miles) and recently it gave me a lot of troubles.

Since I changed timing belt last year, the car began to have non-smooth gear transmission. It began to have relatively higher RPM for gear 1 and 2 (>3300 RPM for first gear). When car is idle, it is shaking with lower than 700 RPM. The situation is getting worse after couple months. In order to resolve this problem, I have spent some money on transimission flush, changing spark plug, and injection cleaning. However, it does not make situation better.

After doing the study in the internet, some body said this might be caused by the malfunction of ECM. The ECM computer mis-control the timing of changing the gear. Replacing ECM could solve this problem. Some body said it could be caused by malfunction of speed sensor. ECM uses the wrong speed to adjust the timing of gear. I am wondering if there is any way I can diagnose which part I should replace.

I am very new here and hope some body can give me some suggestions. Very appreciate!

Thanks,
Chris

 

If the problems occured after the the timing belt was changed, have you, or whoever changed it checked to make sure the timing issnt advanced/retarded and the belt has the proper tension on it?