Ignition Accessories - Coil on Plug (COP) and Signal Probe Kit

Components

The COP probe is usually supplied as a kit (PICO-PP357), which includes both the COP probe and the BNC to BNC cable used to connect the probe to your automotive scope.

The PICO-TA033 is the 3 metre (9 ft 10 in) BNC socket to BNC socket cable with an earth clamp used to connect the COP Ignition Probe to the oscilloscope.

How does it work?

Whenever an electrical current flows, a magnetic field is generated around the conductor. When the conductor is wound into a coil, the magnetic field is intensified. If the current varies, the field strength also varies. Another coil brought into close proximity converts the variations in the magnetic field back into an electric current (transformer effect) which allows you to use the coil–on–plug and signal probe to detect current flow in coils without any electrical connection.

The probe works with most COP systems; it requires no special adaptors, no foil strips, and no batteries. The Pico coil-on-plug and signal probe eliminates the need for back-probing: to use the probe simply press the probe against the coil.

Along with testing COP systems, the coil-on-plug and signal probe can also be used to obtain many other signals, including a secondary ignition waveform on conventional ignition systems.

Designed to save you time, effort and money, the coil-on-plug and signal probe is the fastest way to test both conventional coil-on-plug secondary ignition systems.

Typical Uses

Non-intrusive diagnosis is essential during the initial inspection of a vehicle and the flexible COP/ Signal Probe becomes invaluable in these scenarios.

Misfires are a typical example of where the COP probe excels especially with modern multi cylinder engines and restricted access to coil units.

The shaft of the signal probe can be formed into any shape in order to access coil units that may be buried under intake ducting or manifold assemblies.

Once an offending cylinder has been identified by detecting the misfire, you can be much more confident in determining whether a time consuming repair is warranted.

The COP/Signal Probe is not only confined to misfire detection:

COP units (including restricted access units) HT functionally check

HT Leads and coil towers for HT functionality

Injectors (Petrol/Diesel) solenoid type for an indication of operation

Solenoids for operation check

Oil control valves for operation check

Throttle motors for activity check

Understanding the Sensor's Operation

The COP probe acts very much like an extra secondary winding of a transformer when it is brought close to the coil (see How does it work? above). It therefore shows what the voltage across the actual secondary winding (driving the spark plug) looks like without having to actually connect to it. It senses the magnetic field in the coil.

The display on the left is typical of an ignition coil. Current starts to build up a magnetic field (flux) in the coil until the coil driver switches off the current (this period is the 'dwell time'). The flux begins to reset (decrease) but no current path exists. A large voltage spike results which is impressed across the spark plug electrodes.

The voltage ionises the fuel / air mixture between the spark plug electrodes in the cylinder. This creates a fairly low resistance path for the current generated in the coil by the collapsing flux to flow between the spark plug electrodes.

As the current flows, power is dissipated and heat is produced in the spark (white hot) which ignites the fuel / air mixture. The oscillations at the end of the spark result from the breakdown of the ionised path and the cessation of current flow through the spark.