Ignition System - Information

Ignition System

Each ignition coil that does not have a built-in ignition module must have one connected between the ECU and the ignition coil. It is common to have ignition modules that drive multiple ignition coils.

Distributor System
The distributor in this system distributes energy from the ignition coil to the spark plugs. There are different types of distributors with or without a built-in ignition coil.

ECU -> Ignition Coil -> Distributor -> Ignition Cables -> Spark Plugs

Separate Ignition Coil(s)
The control system sends signals to one or more ignition coils that 

ECU -> Ignition Coil -> Ignition Cables -> Spark Plugs

COP - Coil On Plug
The control system sends signals to each ignition coil that has a built-in ignition module and is mounted directly on the spark plugs.

ECU -> Ignition Coil -> Spark Plug

Common Problems

Ignition Coil
If the ignition coil does not have direct current to the battery or a poor engine ground, not enough high energy can be delivered, resulting in a weaker spark.

Distributor
The rotor and distributor cap are worn and should be replaced. Make sure to size these according to the strength of the ignition coil. A powerful ignition coil in combination with higher RPM generates a lot of heat, which causes the rotor and distributor cap to wear out prematurely.

Ignition Cables
Poor contact can damage ignition cables and other components.

Spark Plugs
Spark plugs can have problems for many different reasons. One issue could be a rich fuel mixture and a poor ignition coil that cannot generate a strong enough spark.

Often, several small problems can combine into a larger one.

Ignition Sequence V8 Engine

A list of ignition sequences for the most common V8 engines.

First numbering of cylinders. Different manufacturers number cylinders differently, so be sure to check this before anything is connected!

Chevrolet numbers their cylinders as follows:
Left 1-3-5-7
Right 2-4-6-8
Cylinder 1 is always the frontmost on the driver's side.

Ford numbers their cylinders as follows:
Left: 5-6-7-8
Right: 1-2-3-4
Cylinder 1 is always the frontmost on the passenger side.

Here is a list of ignition sequences for common V8 engines.

• AMC
  Clockwise rotation
  1-8-4-3-6-5-7-2
  
  
  
• Buick (not "nail head")
  Clockwise rotation
  1-8-4-3-6-5-7-2
  
  
  
• Buick "nail head" 401, 425
  Clockwise rotation
  1-2-7-8-4-5-6-3
  
  
  
• Chevy (not LS)
  Clockwise rotation
  1-8-4-3-6-5-7-2
  
  
  
• GM LS engines
  1-8-7-2-6-5-4-3
  
  
  
• Chrysler Small Block
  Clockwise rotation
  1-8-4-3-6-5-7-2
  
  
  
• Chrysler Big Block and Hemi
  Counterclockwise rotation
  1-8-4-3-6-5-7-2
  
  
  
• Hemi (new)
  1-8-4-3-6-5-7-2
  
  
  
• Ford "flat head"
  1-5-4-8-6-3-7-2
  
  
  
• Ford Y Block
  1-5-4-8-6-3-7-2
  
  
  
• Ford 289, 302FE, 429, 460
  1-5-4-2-6-3-7-8
  
  
  
• Ford 5.0L EFI, 351W, 351, 400
  Counterclockwise rotation
  1-3-7-2-6-5-4-8
  
  
  
• Ford
  1-3-7-2-6-5-4-8
  
  
  
• Oldsmobile
  Counterclockwise rotation
  1-8-4-3-6-5-7-2
  
  
  
• Pontiac
  Counterclockwise rotation
  1-8-4-3-6-5-7-2