Originally Posted by unibus
Still worth it to me for the improvements other than mileage.
That's the way that I feel about it, too, even if I had lost an mpg or so. My "time trials/hot rodding" tank still ended up with 24.3 actual, 25.1 on the EVIC, even that is closer than before.
In trying to relate this to "old school" technology of distributors and carburetors, an off line stumble or bog could sometimes be cured by advancing the timing (2/3 degrees was plenty), adjusting the idle speed and/or adjusting the power valve. That relates to the recalibration of the Powertrain Control Module (GPEC) on all models.
There is no "old school" related to an electronic CVT so this is speculation: it reprograms the Transmission Control Module (TCM)to allow it to move to the lowest position possible (the original didn't quite put the variators in that position?) and/or it changes the other shift positions/ratios.
It could be that the reason it "appears" to have lost some power on the upper end is that it's now getting full advance on the timing sooner where before that full advance didn't kick in until the RPM's were higher giving you a feel of an additional kick in the pants.
There are two different Labor Codes for this TSB. One is for recalibrating the Powertrain Control Module (GPEC) without changing the CVT's Transmission Control Module (TCM) and the other Labor Code is for reprogramming both. This covers BOTH the CVT and the 5 Speed.
For me this is the most cost affective performance improvement that anybody can do with a build date of 4/21/07 or earlier! It's FREE