| The
transmission control unit or TCU is the computer which
controls the transmission's operation. These TCU's
have been socketed to allow updating of the software and come with new
ECUtune shift maps, pressure control maps, overheat protections,
and gear ratios. They are ready to plug in and run
on any SVX. Protect your transmission, improve
performance, and improve fuel economy without ever touching
the transmission or altering vehicle wiring. One of the ECUtune adjustments made was
to lower the trigger temperature for the ATF temperature
warning light to come on at 100°C
(212°F). It will shut back off when the ATF
temperature drops below 95°C (203°F). This was done
mainly because the 4EAT transmission used in the SVX
overheats badly when overfilled with fluid--a mistake many
owners make because the dipstick is notoriously hard to
read. A warning light at 212°F should alert such an
owner to his/her mistake in time to save the transmission.
The thresholds for the overheat mode have been reduced to the
same temperatures so that the transmission control unit
begins taking steps to reduce ATF temp (such as locking the
torque converter and changing the shift maps used) at the
same time it warns the driver.
Almost all SVX transmission failures are high clutch and
brake band burn outs caused by slippage during light
cruise in 3rd or 4th gear. The ECUtune performance
TCU prevents this slippage by increasing hydraulic apply
pressures through the TCU's control of the pressure line
duty control solenoid A. The
stock solenoid a duty control maps for 3rd and 4th gear
result in a 50% to 60% duty bleeding off line pressure under
light cruise. The
ECUtune solenoid a duty control maps only allow a 6% to
12% duty bleeding off line pressure under light cruise.
The higher hydraulic apply pressures afforded under light
cruise from the higher line pressures of the ECUtune maps
save SVX transmissions from their biggest Achilles heel.
The shift maps dictate
when to up-shift or down-shift from the current gear based
on throttle input and vehicle speed. The ECUtune maps down-shift
to first gear with less throttle and generally hold gears
longer with moderate throttle so it is not necessary to
floor the gas to get it to go (ECUtune
1-2 and 2-1 shift maps). This gives the car a
much sportier feel around town while greatly improving fuel
economy because less throttle is needed to attain desired
performance.
To request custom rev. limits please email to the address
at the bottom of the webpage. |
