Ignition System Diagnosis
Chapter 12 and 13 - Shop Manual
Safety
•	Beware of sparks and arcs
•	Turn off ignition before serving system
•	Watch for fuel leaks
–	Ignition will cause gas to burn!

Basic “no start”
•	Check easy stuff first (always) (Spark?)
•	Power to coil?  Ground?
•	Check cap and rotor
•	Coil wires
•	Spark plug wires
•	Trigger to coil - EASY!!!
•	Plugs
Visual Inspection
•	Loose, corroded primary wires and connections
•	Loose, corroded secondary wires and connections
•	Damage to the cap and rotor
•	Damage to the primary switching device
•	Electronic control
Plug Wires
•	Spray with mist of water to see arcs or listen for snapping noise
•	Should be tightly pushed onto plug and into distributor or coil pack
•	Should be flexible
•	May need to be routed correctly
•	Do a “wiggle test”
•	Burns or melted wires
•	Measure with an Ohm meter 10Kohms per foot
Coil
•	Measured with an ohm meter (USE THE BOOK!)
–	Primary circuit
–	Secondary circuit
•	damaged terminals
•	corroded terminals (secondary)
•	Oil leaks
•	Mounted securely
Cap and Rotor
•	Cracked plastic
•	Loose screws or mounting
•	Carbon tracking
•	Moisture in cap
•	Burnt rotor tip
•	Burned terminals on cap
Electronic Primary circuits

•	Broken module housings
•	Wire and corrosion damage
•	Hooking up other devices
•	Missing heat conductive grease
•	Damaged sensors
–	Hall effect sensor
–	Crankshaft sensor
Distributorless Ignition
•	Spark Plug wires and Plugs
•	Use the book to test a coil pack
•	Oil leaks from coil
•	Check for power and ground to coil pack (as per book)
Plug Diagnosis
•	Keep track of plugs and cylinders
•	Put them back in the “same hole”
•	gap if needed
•	check for wear signs
•	LAST thing to check with ignition diagnosis
•	Use di-electric grease and anti-seize
Plug installing
•	Don’t over goop plug with anti-seize – it kills O2 sensors
•	Don’t put the grease on the threads, only the “top” of the plug. – it also kills O2 sensors.
•	Torque all plugs
•	Gap all plugs, but not Bosch (style) Platinum!
Platinum Plugs
•	Longer service life (100K miles)
•	Quicker heat up and burn off times
•	Can’t gap due to small amount of metal on tip.  
•	Tip is *coated* with Platinum atoms
•	Bosch has only used 5 (five) pounds of platinum in manufacturing for ALL its plugs made since 1985!!!