Waste Spark System Specifications; Ignition Components - Mercury MerCruiser Service Manual

DMT 2004 Digital Multimeter
H z TEMP
m A
A
V
H z
mV
IG
OFF
IP
TEMP
A m A C O M
V H z

Waste Spark System Specifications

Waste spark system is an ignition system used with some two‑ and four‑stroke cycle internal combustion engines. In a wasted
spark system, the spark plugs fire in pairs even though one is on its compression stroke and one is on its exhaust stroke. The
extra spark on the exhaust stroke has no effect and is thus "wasted." This design has the number of components in a typical
ignition system, while the extra spark, against much reduced dielectric resistance, barely impacts on the lifespan of modern
ignition components. In a typical engine, it requires only about 2–3 kV to fire the cylinder on the exhaust strokes. The remaining
coil energy is available to fire the spark plug under compression (typically about 8–12 kV). PCM 112 ignition system uses
double‑ended driverless ignition coils. Each coil is a double‑ended waste spark, so one coil will fire two cylinders. One cylinder
will be on the compression stroke and the other cylinder will be on the exhaust stroke.
Coil
Description
Primary coil resistance
Secondary coil resistance
Spark Plugs
Engine
6.2L
Firing Order and Ignition Timing
Description
Firing order
Ignition timing

Ignition Components

b
For diagnostics also refer to the PCM 112 Diagnostic Manual.
90-8M0099748 eng DECEMBER 2015
Measures RPM on spark ignition (SI) engines, ohms, amperes, AC and DC
voltages; records maximums and minimums simultaneously, and accurately
reads in high RFI environments.
4516
OEM Spark Plug
NGK BPR5EFS‑13
c
e
a
91‑892647A01
1.30 mm (0.051 in.)
Specification
1‑8‑4‑3‑6‑5‑7‑2
PCM
a -
b -
c -
d -
e -
d
59408
© 2016 Mercury Marine
Waste Spark System
Specification
0.30–0.50 Ω
7,200–8,800 Ω
Gap
Battery
PCM
Ignition coils
Spark plugs
Crankshaft position sensor
Page 4B-3