Skip to content

Ignition Overview

Ignition overview:

The EMIT Ignition Controller Module (ICM) is an electronically controlled ignition system that features highly accurate and reliable spark control and monitoring capabilities through the use of transistorized inductive technology. The ICM is available in two types: The ICM1 and ICM2, both of which are available in versions with a maximum of 8 or 16 cylinders. The ICM2 is connected directly to the auxiliary drive of an engine for sensing the position of the engine, while the ICM1 uses external timing sources for applications without an auxiliary drive. All ignition modules offer the same feature set and are appropriate for rich-burn or lean-burn combustion and naturally-aspirated or turbo-charged engines fueled by natural gas or propane.

The ICM utilizes transistorized inductive technology to build and transfer energy for spark initialization and control. By using the latest transistor technology, a high speed digital signal processor, and high-energy coils for inductive ignition, the ICM achieves precise and accurate control of a long duration spark that burns beyond that of a capacitive discharge system. The longer spark duration provides reliable combustion of the air/fuel mixture and performs particularly well for poorly mixed air/fuel mixtures, poor quality fuels, and lean air/fuel mixtures. Other benefits of inductive discharge systems include superior misfire performance, higher energy transfer efficiency to the spark, and reduced electromagnetic interference.

Capacitive discharge ignition systems have a higher peak spark voltage, but due to the corresponding short spark duration does not definitely translate to improved combustion. To overcome this, some capacitive systems need to spark multiple times to ensure the mixture is combusted if the original sparks did not ignite or only partially ignited the mixture. Multiple sparks reduce the ability to control peak cylinder pressure and unnecessarily wear coils, wires, and spark plugs. With the longer spark duration of the ICM, one spark provides sufficient energy to ignite the mixture.

For an ICM1, the timing input can be sourced from different locations on the engine depending on the application. In wasted spark mode, the ignition utilizes two magnetic pickups: one for flywheel teeth and one for flywheel index to indicate top dead center of the reference cylinder. By using only two magnetic pickups, no additional sensors are needed for the camshaft timing, which is generally more difficult to access for installation. Alternatively, the ignition can use one magnetic pickup on the flywheel teeth and one hall sensor on the TDC of the camshaft to fire only on compression stroke. Lastly, the ICM1 can have the timing source from a camshaft timing disk, which has a timing mark for each cylinder, and an additional mark for the cylinder that is the reference cylinder.

For an ICM2, no external timing inputs are required. The ICM2 bolts directly to the engine’s auxilary drive location (magneto drive) and uses an internal encoder to detect the position of the camshaft. Internal gearing, in a ratio specific to the engine application, reduces the auxiliary drive to the speed of the camshaft.

Configuration, ignition status, timing adjustment, and diagnostic tools are all presented through the EIM’s 8” touchscreen display. The touchscreen allows the ICM to be fully accessible and utilized without the need for a PC connection, external software, or any chips or keys. If installed with an EMIT AFRC or EMD, the systems can all be accessed through the same display and user interface.

Timing control is designed to automatically advance and retard based on changes to RPM and, optionally, load while also being quickly adjusted manually. Accuracy of the timing is based on engine RPM and is reduced as RPM increases. As an example, timing is accurate within +/-0.090 degrees at 1500 RPM and +/-0.180 degrees at the maximum RPM of 3000. Timing ignition adjustment limited to a range of 5 degrees BTDC and 60 degrees BTDC.

Diagnostic, testing, and control features for the ICM include a range of tools. Conditions for up to eight cylinders at a time can be displayed simultaneously for visual comparison. Various aspects of spark conditions can be setup to provide warnings for potential issues. For engine protection, the ICM offers overspeed and underspeed shutdowns. The ICM can also trigger a warning or shutdown for poor spark performance, such as short spark duration or high misfire count. Other features include verification of timing inputs, verification of coil and harness wiring, top dead center input calibration, compression testing mode, adjustable fuel relay control, adjustable ignition start control, adjustable dwell time, and secondary spark waveform graphing.

Feedback and Knowledge Base