Originally Posted by
LilSick
i am not experienced with THAT fully electronic TRANS
not like i am with the fully electronic zf8's
i understand those very well
prolly better than i understand the ole 727 and its lil brother the 904
i have some experience tuning 46re and 48re but am not pro
here is what i know:
The only logic in the JTEC+ for the RE transmissions is governor pressure = 1 PSI per MPH. When in 4x4 low they limit pressure to 15psi to keep the trans from shifting to anything higher than 2nd gear. Shift timing = line pressure+shift spring vs governor pressure. Line pressure = spring pressure + throttle valve (which adds additional spring pressure) to raise line pressure (based on throttle). You can buy spring kits (shift kits) to adjust shift timing to any RPM you'd like with a RE trans. The 904/727 from the early 60s to the end of the RE trans in the early 2000s all use the same springs, majority of parts can be swapped throughout those years.
Transmissions such as the 45RFE, 545RFE, and 68RFE, are fully electronic so they must be tuned in the PCM OR TCM. They use no springs for control. Instead they use multiple electric solenoids to control shift timing and firmness. Those tables were not added to JTEC until 99 starting with Jeeps, when the 3.7/4.7 engines and the 45RFE trans came out.
HP tuners could not add options to tune the governor pressure vs speed value or torque converter lockup vs vehicle speed vs throttle position because those parameters are not in normal X/Y axis tables. They are instead hard coded in the logic. You cannot change that part of the tune on a RFE transmission.
Without a log i cannot tune any of them : )
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