following questions should be answered to the best
of your ability. Some information may not require
an answer if your motor is stock. The more
information understood the better optimized your
programming will be.
displacement IE: 305, 350, 355, 383, 406, etc.
Transmission type: Automatic, or manual.
Compression ratio and cylinder head type.
specifications: Duration & lift @ .050 &
Lobe separation angle (LSA)
Injector size: Brand & number preferred.
rail number IE: 1708XXXX, or if using an
adjustable pressure regulator? What is the desired
pressure at idle with vacuum disconnected. I will
recommend if asked.
Vehicle Anti Theft System (VATS): Enable / Disable
Exhaust gas recirculation (EGR): Enable / Disable
Speed Sensor (VSS): Enable / Disable.
Cooling fan(s) settings: 160, 180, or 195. I
recommend using at least a 180 thermostat for TPI.
#11 Knock sensor: High compression, and high
lift cams can create chatter that will be picked
up by the sensor. Knock sensor may need to be
disabled in certain combinations.
limiter: Default is 255 mph / or specify desired
limiter: Default is 10,000 RPM / I recommend
limiting it to 800 rpm over peak horsepower
type of ECM: Speed Density 1990, 91, and 92. ECM
#'s 1227730, 16196344, 16198262, 1227277,
16197128, 16198260, or Mass Air
1986, 87, 88, and 89. ECM #'s 1227165, 16198259,
to those against using to large of a
fuel injector. A 24 lb. 3 bar (43.5 psi.) injector
can easily handle upwards of 400 hp by turning up
the fuel pressure to 50 psi. High impedance
injectors require at least a 2 millisecond pulse
width at idle. If you run to large injector you
will sacrifice your idle quality. The single
greatest misnomer about TPI is injector sizing. GM
used many different sized injectors, and at
different pressures during the TPI years. It is
critical that we get the flow rate set correctly
for any combination. The manufactures have learned
that higher pressures are better. Today's LS1's
are running 3.7 bar (55 psi). This gives a better
spray pattern to optimize the use of fuel. 350's
should run 21 lb. injectors with the pressure
turned up based on modifications. 383 to 406's
should use 24, but some very high flow
combinations can run 30's.
Speed Sensor (VSS) is highly recommended. EGR will
not function, and torque converter won't lockup
without VSS being hooked up unless a 3rd party
device is used. Programming is
optimized to know whether the vehicle is moving or
not. You will not be smog legal without it,
and the motor may die in certain deceleration
situations. Mass Air systems used a 2 pulse square
wave, but speed density used a 4 pulse sine wave.
You may use any sine wave sensor with speed
density, and the output signal may be modified in
the programming. IE: A later model T56 with a 40
pulse sine wave can be used, and the input signal
modified in the programming.
been asked to adjust speedometers for different
gear ratios and tire heights. Although GM did
create numerous broadcast codes for TPI and
referred to them by gear ratios. The Memcal nor
ECM controls the speedometer. The 4 pulse sine
wave (4000 pulse per mile) is received by the ECM.
It then sends out a signal to a DRAC module
(Digital Ration Adapter Controller) which performs
the correct calibration for the speedometer. GM
only used two basic fuel tables for speed density,
but used numerous spark tables. Itís my
experience that these spark tables are not
correlated with gear ratios, but rather chosen
based on expected performance of the model for
which the broadcast code was designed. Some models
may have replaceable gears at the VSS that can be
changed. These years did not use the DRAC module.
pump, or Air Injection Reactor (AIR), and the
Charcoal Canister Purge (CCP) will not set a code
in TPI and does need to be programmed out.
However, it can shut it off if it bothers you to
see it on your diagnostic equipment.
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