Cheap Electronic Shift Improver for Automatic Transmissions
by
www.FRKNLO.com
Purpose
Instead of buying a electronic shift improver you can make your own using
resistors.
How it Works
Heres a quote from the GM Service Manual for a 4L60E automatic
transmission.
The transmission pressure control solenoid (PCS) is an electronic
pressure regulator that controls pressure based on the current flow through
gh its coil winding. The magnetic field produced by the coil moves the solenoids internal valve which varies pressure to the pressure
regulator valve.
Thus, the PCM controls the pressure control solenoid by commanding
current between 0.1 and 1.1 amps. This changes the duty cycle of the
solenoid, which can range between 5% and 95% (typically less than 60%).
High amperage (1.1 amps) corresponds to minimum line pressure,
and low amperage(0.1 amp) corresponds to maximum line pressure (if
the solenoid loses power, the transmission defaults to maximum line
pressure).
The PCM commands the line pressure values, using inputs such as
engine speed and throttle position sensor voltage. The pressure
control solenoid takes the place of the throttle valve or the vacuumed
tor that was used on past model transmissions
what the electronic shift improver controls is line pressure by varying the amount
of amperage going to the PCS. The way this is done is by shunting a resistor to
ground (parallel resistor to solenoid). What occurs is more amperage go through
the resistor and less to the PCS (solenoid), in effect bring the line pressure up
which corresponds to firmer shifting..... My brother and I tried it and it worked
by using a simple passive element, a resistor.
Materials
1. Various resistors ranging from 2−3 ohms to 100 ohms. The lower the
resistor value => firmer shifting.
2. wires; same gage as computer wire. Maybe 14−18 gage.
3. 2 splices; same gage as computer wire.
4. male/female connectors (to allow changing various resistors)
Skills Required
Basic understanding of electrical circuits; mechanically−clined individual.
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METHOD
WARNING: We did not do any long−term testing and thus we won’t be reliable for a
ny shit that goes wrong in the long run. There’s also more debate on the wear
and tear of the clutch due to the high line pressure for a firmer shift. From the
numerous debates, the best way to increase shifting performance is by upgrading
the valve body, not electronically. Upgrades via valve body is available from
b&m, jet performance and transgo).
1.0 COMPUTER AND TRANSMISSION INTERFACE
1.1 located on the passenger side of the engine bay; mounted directly to
the inner fender wheels. Before proceeding further, detach the
negative (−) wire from the truck’s 12V battery.
1.2 locate the EPC Solenoid Ground & EPC Solenoid Positive wires.
check out
www.transonline.com for specific information for your year
and model of transmission.
WARNING: proceed with caution when working under a truck and near
exhaust piping or other hot sources.
Another way to find the wires is to locate the two wires that is
directly connected to the automatic transmissions; then find the same
colored wires at the computer’s output wires.
NOTE: check continuity to ensure the correct wires.
2.0
SHUNT RESISTOR(S)
2.1 Splice the two EPC solenoid ground / positive wires using the splice
2.2 Attach resistor(S). Check paragraph 3.0 for fine tuning.
2.3 Re−attach negative wire to battery.
2.4 TEST TRUCK in a safe manner.
3.0
FINE TUNING
3.1 Low resistance (1 − 50 ohms) => firmer shifting; race setting
high resistance (50+ ohms) => stage 1, 2 setting
3.2 Firmer Shifting with existing resistor: Add resistors in PARALLEL.
For example, connect 1 and 3 together, and 2 and 4 together. this
lowers the resistance of the resistors:
1 −−−−WWWW−−−−−− 2
3 −−−−WWWW−−−−−− 4
3.3 de−firmer shifting with existing resistor: add resistors in SERIES.
For example, connect 2 and 3.
1 −−−−−−−WWWW−−−−−−2 −−− 3 −−−−−WWWW−−−−−− 4
