5B.15
Section 5B
EFI Fuel System
5B
Figure 5B-18. Ignition Coil.
NOTE:
Do not ground the coils with the ignition
‘‘on,’’ as they may overheat or spark.
1. Disconnect the main harness connector from ECU.
Locate pins #30 and #31 in the 32 pin connector.
See page 5B.24.
2. Disconnect the connector from the relay and
locate terminal #87 in connector.
3. Using an ohmmeter set on the Rx1 scale, check
the resistance in circuits as follows: Check
between terminal #87 and pin #30 for coil #1.
Repeat the test between terminal #87 and pin #31
for coil #2.
A reading of 1.8-4.0
Ω
Ω
Ω
Ω
Ω
in each test indicates that
the wiring and coil primary circuits are OK.
a. If the reading(s) are not within specified range,
check and clean connections and retest.
b. If the reading(s) are still not within the
specified range, test the coils separately from
the main harness as follows:
1.
Disconnect the red and black primary
leads from the coil terminals.
2.
Connect an ohmmeter set on the Rx1
scale to the primary terminals. Primary
resistance should be 1.8-2.5
Ω
Ω
Ω
Ω
Ω
.
3.
Disconnect the secondary lead from the
spark plug. Connect an ohmmeter set on
the Rx10K scale between the spark plug
boot terminal and the red primary terminal.
Secondary resistance should be 13,000-
17,500
Ω
Ω
Ω
Ω
Ω
.
14. Clean any dirt accumulation from the sealing/
mounting area of the faulty injector(s) and
disconnect the electrical connector(s).
15. Pull the retaining clip off the top of the injector(s)
and remove from manifold.
16. Reverse the appropriate procedures to install the
new injector(s) and reassemble the engine. Use
new O-Rings any time an injector is removed (new
replacement injectors include new O-Rings).
Lubricate O-Rings lightly with oil. Torque fuel rail
and blower housing mounting screws to 3.9 N·m
(35 in. lb.), and the intake manifold and air cleaner
mounting screws to 9.9 N·m (88 in. lb.).
Injector problems due to dirt or clogging are generally
unlikely, due to the design of the injectors, the high fuel
pressure, and the detergent additives in the gasoline.
Symptoms that could be caused by dirty/clogged
injectors include rough idle, hesitation/stumble during
acceleration, or triggering of fault codes related to fuel
delivery. Injector clogging is usually caused by a buildup
of deposits on the director plate, restricting the flow of
fuel, resulting in a poor spray pattern. Some contributing
factors to injector clogging include higher than normal
operating temperatures, short operating intervals, and
dirty, incorrect, or poor quality fuel. Cleaning of clogged
injectors is not recommended; they should be replaced.
Additives and higher grades of fuel can be used as a
preventative measure if clogging has been a problem.
Ignition System
General
A high voltage, solid state, battery ignition system is
used with the EFI system. The ECU controls the ignition
output and timing through transistorized control of the
primary current delivered to the coils. Based on input
from the speed sensor, the ECU determines the correct
firing point for the speed at which the engine is running.
At the proper instant, it releases the flow of primary
current to the coil. The primary current induces high
voltage in the coil secondary, which is then delivered to
the spark plug. Each coil fires every revolution, but every
other spark is “wasted.”
Service
Except for removing the spark plug lead by unscrewing
it from the secondary tower (see Figure 5B-18), no coil
servicing is possible. If a coil is determined to be faulty,
replacement is necessary. An ohmmeter may be used
to test the wiring and coil windings.
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