Table D.1. 1:
Recommended fuel injector selection for various wiring configurations. Note that
the values given are for individual injector resistance, NOT for the total circuit resistance. TBI-
style injectors cannot be run with more than one-per-channel.
Injector type
Individual Injector
Resistance for
1 Injector per Driver
Individual Injector
Resistance for
2 Injectors per Driver
Low Impedance
1.1 - 4 ohms
2.2 - 4.4 ohms
High Impedance
6 ohms or above
12 ohms or above
Figure D.1. 1:
Parallel wiring of fuel injectors. Note that
injectors have an electrical polarity. Typically, positive is on
the side marked above.
To determine the current flow through an injector circuit, follow the equation below.
Current Flow through Injector Circuit = Battery Voltage
÷
Injector Circuit Resistance
Injectors should always be wired in parallel when more that one injector is used on a channel (see
Figure
D.1. 1
). When two injectors are used on a channel, the current flow through each individual injector will be
half of the flow through the injector circuit. When three injectors are used on a channel, the current flow
through each individual injector will be one-third of the flow through the injector circuit (however, more
than 2 injectors per driver should never be necessary).
Current Flow per Injector = [1
÷
# of injectors per driver]
×
Current Flow through Circuit
Peak-and-Hold Mode Injector Channel Current
0
1
2
3
4
5
0
1
2
3
4
5
Injector On-Time (ms)
Injector Channel
Amperage (amps)
Injector
Peak Current
Hold Current
Figure D.1. 2:
Injector channel current
for a typical peak-and-hold setup.
As far as performance, low impedance injectors are preferred. The reason is simple: low impedance
injectors have a faster response time than high impedance injectors. This means that low impedance
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TECgt Manual Version 2.0
- Page 51 -
©2008 Electromotive, Inc.