Precision Turbo and Engine BigStuff3 GEN3 PRO SEFI (LS1) System Hardware & BigComm Software - Manual (Page 38)

BigStuff3 Pro SEFI System (LS1)
Version 1.0 37
• Rotate the crankshaft back to 30 o
• Very slowly, rotate the crankshaft clockwise towards TDC. As soon as the voltmeter
reading drops to zero Volts (or very close to zero Volts) stop rotating the crankshaft.
BTDC position and the voltmeter attached to the E3 and
J2 terminals, the voltmeter should read 12 Volts (the Switched 12-Volt wire on the main
harness must be is connected and “live”).
• Next, make sure the main wire harness crankshaft connector is attached to the stock LS1
crankshaft sensor and the main wire harness, Switched 12-Volt wire is connected and
“live”.
• Attach the Voltmeter’s red lead to the main wire harness terminal J3 (Signal). Leave the
Voltmeter’s black lead inserted into the main wire harness header connector terminal J2
(Gnd). These terminals are attached to wires routed back to the crankshaft sensor
.
Again, make sure the probes (sewing needles) inserted into the J3 and J2 terminals do not
touch each other. Doing so will damage the main wire harness!
The voltmeter should
read 12 Volts.
• Very slowly, rotate the crankshaft clockwise. As soon as the voltmeter reading drops to
zero Volts (or very close to zero Volts) stop rotating the crankshaft.
• Take the crankshaft reading. If the crankshaft (balancer) TDC timing mark is after TDC
(ATDC) e.g. 10
o
, input 350
o
(360
o
- 10
o
= 350
o
) into the Crank Reference input box. If
the crankshaft timing mark is before TDC, add the value, e.g. 10
o
to 360
o
(360
o
+ 10
o
=
370
o
• Lastly, it is important to confirm that the timing at the crank, when the engine is running,
is equal to the values in the spark table. Set all the values in the spark table to thirty (30)
degrees and then make sure the balancer mark, representing 30
) into the Crank Reference input box.
o
lines up with the pointer.
• Note: The crank reference table has ¼ degree resolution.
19. Dwell Time Table
The dwell time affects the amount of primary current in the ignition coil. The longer the coil
dwell the more primary current available for a spark event. GM coils are current limited at 6
Amps to 7 Amps. GM coils reach their current limit at approximately 6 ms of dwell time.
BigStuff’s GEN3 ECU allows for coil saturation at high RPM, where maximum spark energy is
required, but also allows the coils to run at lower dwell times (ms), at lower RPM, to avoid
overheating the coils.
The 1 x 16 table allows coil dwell-time to be set as a function of engine RPM.
Note: The RPM values, at the bottom of the dwell-time input table, are established when the
Load vs. RPM Axis table is configured.