4.5.1 Wiring
The injectors have to be wired on the engine. Some of the kits include an injector harness like the
Lexus V8. Make sure that the combination of injectors is correct as this will influence consistency
between cylinders. Injectors come in 2 groups. High resistance (12 to 18 Ohm) and low resistance
(2 to 4 Ohm). For high resistance injectors you may add up to 4 injectors per channel. They are
always connected in parallel. Low resistor injectors however should be limited to one per channel.
Or they can be connected 2 in series. They should actually be connected to a different current
limiting driver. They may heat up if not properly cooled and eventually self-destruct. For injector
wiring see specific wiring details on the relevant wiring diagrams on CD.
4.5.2 Sequential injection
There are enough outputs available for 4 cylinder engines to do sequential injection and wasted
spark. Specific models only. This however will require a TDC signal indicating that cylinder 1 is on
firing and is normally obtained from a separate cam sensor. Here fuel is injected once every 2
RPM’s and always start at Bottom Deck Centre (BDC). Since there is not much to gain over the
next method, we design most of the software for Split-Sequential injection. Each injector has its
own driver from the ECU. See the specific wiring diagram.
4.5.3 Split-Sequential injection
The ECU is designed to do split-sequential injection. This method will inject on the two cylinders
that move up and down together. It will inject once per RPM and will start at BDC. Fuel is injected
very accurately and excellent CO adjustments can be achieved. The advantage of this method is
that each cylinder receives it fuel under the same conditions, resulting in very smooth idling and
revving. It is definitely better on power and consumption than the batch injection method. Injectors
are wired in the same sequence as wasted spark. Split the firing order in 2 and write se second
half next to the first half. See example. Then group the injectors using the first of both halves, then
the second then the third then the fourth. Two injectors are wired on each driver from the ECU. On
the CD are drawings for these injector combinations. See the chart below:
ECU
Driver WireColor FiringOrder4Cyl Subaru
FiringOrderV6
Cyl
FiringOrderV6
Cyl
FiringOrderStr6
Cyl
Fir
Ch
1342or1243 1324 123456 142536 153624 18
INJ1 White 1&4 1&2 1&4 1&5 1&6 1
INJ2 Black 2&3 3&4 2&5 4&3 5&2 8
INJ3 Green 3&6 2&6 3&4 4
INJ4 Yellow 3
Ex: Lexus V8 Firing order: 1 8 4 3 6 5 7 2
1 8 4 3 is 1&6 = White, 8&5 = Black, 4&7 = Green, 3&2 = Yellow
6 5 7 2
4.5.4 Batch fire
With this method, two injector drivers are being pulsed 180° out of faze. Although not preferred,
fuel metering and timing is done very accurately and should still give excellent results. Split the
injectors in two groups to divide the current on the 2 driver outputs. Put alternate numbers on the
firing order together to ensure a more even fuel distribution. For bigger engines keep the mean
supply current below 7A. More outputs are available in the intermediate and advance units. See
the specific wiring diagram.
4.5.5 Throttle Body Injection
With this method, injectors are situated at the throttle body. Spitronics do a Weber 2 Injector and a
Holley 4 Injector conversion. With these conversions injectors is situated on the top of the butterfly.
The ECU also has a special program to pulse these injectors in sequence and vary the pulses per
RPM to get a much smoother distribution of the fuel mixture. See the specific wiring diagram to
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