I have a 92 sc300 with an awkward problem: whenever I floor it, say in second gear, it won't upshift to third unless I competely let off the gas. It also does this when just revving at a stand still in park or neutral. Could this be caused by a bad ecu and a malfunctioning rev limiter? Or would this be something more tranny related such as old fliud in need of a flush? Other than that it shifts just fine and the gears change smoothly. im not too familiar with automatic transmissions, thats why I'm asking anyone with some kowledge on the subject. My biggest concern is that I am planning on on going NA-T, so I'm worried something might blow up before I get a chance to do a manual swap. Does anyone have any ideas as to what may be causing this?

 

If you're planning to go NA-T then you need to take your time and do ALL maintenance items. There's nothing worse than rushing into boost and blowing your money on the setup and then having issues later on.

Back to the issue at hand, it sounds like your Throttle Position Sensor is mis-adjusted. If you let off the throttle slightly at high rpm does it shift (i.e. only WOT won't shift).

 

yea, if I remember correctly when I let off the throttle it will shift, it was just WOT that wouldn't