calebhwang

Hey guys, so I have my 1993 Lexus GS300, everything stock, both motor and transmission recently rebuilt. The only problem I have is that the transmission does not shift from 1st to 2nd for about 4 seconds, then it will eventually shift. This only happens when the engine is cold. After the engine warms up, it drives and shifts like butter. Not a single problem. No lights and no trouble codes.

I went in depth with diagnostics on this problem, scoping the PCM with ECT, TPS, VSS, and all other inputs, then checking the all shift solenoid outputs from the PCM. The PCM will not activate the shift solenoids during the 4 or 5 seconds of not shifting, then as soon as the PCM activates the shift solenoids, it will shift into 2nd gear. This happens for about 2 or 3 minutes after starting, or around 3 or 4 accelerations. Then the PCM seems to shift the transmission normally without any issues.

I know that the PCM has different transmission shifting tables with different temperatures, but never have I seen it to where it will hold 1st gear for 4 or 5 seconds. I wanted to get you guys' help with this one and to find out if anyone else has the same problem like this.

The only thing that is bothering me is the fact that the transmission shifted fine before the rebuild, and not a few months later, this is happening. It has been close to a year to be exact, and around 2k miles since the engine and transmission rebuild.

Help guys!