95 Ls400 Transmission

[billhinton]

I have had my transmission rebuilt but they didn't get it exactly right. Is was jarring when it shifted and not smooth at all. This has gone on for some time. Recently my "check engine" light came on with a emission code or possible vacuum line problem.

The transmission is now as smooth as owl shi--. I know these transmissions are electronically controlled and not by vacuum but is there a genius who can tell me why the transmission magically smoothed out at this exact time.

Thanks

[eatingupblacktop]

From what you describe, your tranny is probably not the problem. Sounds like the rough performance was due to the ecm hunting to compensate for either an air leak or a fuel mix issue. With the cel coming on, the computer has either given up the hunt and posted a warning for you or has found a setting that has smoothed things out until you get it serviced.

[wwest]

I have had my transmission rebuilt but they didn't get it exactly right. Is was jarring when it shifted and not smooth at all. This has gone on for some time. Recently my "check engine" light came on with a emission code or possible vacuum line problem.

The transmission is now as smooth as owl shi--. I know these transmissions are electronically controlled and not by vacuum but is there a genius who can tell me why the transmission magically smoothed out at this exact time.

Thanks

My guess would be that the engine/transmission ECU firmware automatically switched the transmission into "snow" mode with the issue of potential degraded engine performance came about. Basically the same reason VSC/TC/BA are disabled with a CEL. Probably disabled the OD mode at the same time.