ICM Overview
Ignition Documents and Guides
Ignition Engineering Adjustments
Ignition ICM2 Encoder Visualization
Ignition Singly Cylinder Dropout Test
Overview
Ignition overview: https://www.youtube.com/watch?v=H8GPSxc_so0
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.
Alarms
The ICM presents ignition diagnostics in the form of visual tools, user-defined alarms and warnings, and a quick-view for active faults.
ALARMS AND WARNINGS
Adjustable alarms and faults are available on the Ignition Alarms screen (Pg. 407). Alarm thresholds on this screen can be configured at any time to trigger fault conditions for the events listed below.
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Ignition Alarms Screen
When an alarm occurs, the “Alarms” button in the footer of the display will flash the “Alarm” text and display the current number of alarms. To clear the alarm, the “Reset Alarm” button must be selected from the Alarm View screen (Pg. 41). The overspeed, underspeed, and critical timing error alarms will shut down the engine. The other diagnostic trigger values will cause an alarm but the engine will stay running.
To set a disable a diagnostic trigger, select the relevant button and press “Disable Highlighted Alarm”. A disabled alarm will show “---“ in its value box. Note that “Overspeed RPM” cannot be disabled.
RPM Overspeed
- “RPM Overspeed” is the setpoint value for a high RPM shutdown
- This value is configured during the ignition setup process but can be updated at any moment
- The maximum RPM overspeed setpoint is 3000 RPM
RPM Underspeed
- “RPM Underspeed” is the setpoint value for a low RPM shutdown
- Alarm is only engaged after a startup grace period expires
- Startup grace period is adjustable up to 20 minutes
Spark Duration
- A spark duration warning can be configured by defining the “Maximum Spark Duration” and “Minimum Spark Duration” values
- Valid ranges for spark duration are between 0.5 and 20 ms
- A spark duration fault provides a warning and does not shutdown the ignition
Spark Deviation from Engine Average
- The spark deviation warning is intended to identify any cylinder or ignition component issues by comparing the individual spark duration with the engine average duration
- Valid ranges for spark duration deviation are between 0.1 and 10 ms
- A spark deviation fault provides a warning and does not shutdown the ignition
Maximum Cycle-to-Cycle Variation
- The cycle-to-cycle variation warning is intended to identify any cylinder or ignition component issues by identifying cylinders that exceed a user-define cycle-to-cycle spark duration threshold
- Valid ranges for cycle-to-cycle variation are between 0.1 and 10 ms
- A cycle-to-cycle variation fault provides a warning and does not shutdown the ignition
Maximum Cylinder Misfires
- If a cylinder’s spark plug is detected to have not sparked properly a misfire count for that cylinder will be incremented
- The Maximum Cylinder Misfires value gives a threshold value past which an alarm will be triggered
- The misfire alarm will show a list of cylinders that are over the threshold value
(Built In) Critical Timing Error – Missing Index
- If the crank TDC index signal has not been detect for 2.0 seconds while the engine is running, the ignition will shutdown and display the fault in the Alarms screen (Pg. 40)
- Potential causes of this fault include:
- TDC magnetic pickup installed too far from the trigger bolt to detect
- Excessive oil and metal shavings on the pole of the TDC magnetic pickup
- Improper wiring of the TDC magnetic pickup
- This error will also show similarly in modes that use a camshaft sensor as a TDC reference if that signal is lost for 2.0 seconds
(Built In) Shutdown Alarms
The Ignition has a variety of shutdown diagnostic alarms that are always enabled. After a shutdown, the EIM will evaluate the conditions of the ignition before and after the engine stopping. If an unusual or problematic condition exists, it will trigger an alarm under code ICM007, and will provide additional information to the user as to what might have contributed to the shutdown.
ICM2 Encoder Visualization
For the ICM2, the encoder visualization screen can be accessed by going to “Setup and Testing” from the Ignition Home screen, then clicking “Encoder Position / Cam Information”.
This page shows the position of the encoder (camshaft position) and the saved zero point. It can be used to see if the reference cylinder is on the compression or exhaust stroke, and also can be used to see if the calibration was successful (if the red lines are aligned then the flywheel position should be at or near TDC).
If the ICM2 has to be removed for maintenance, this screen should be used beforehand to set the engine at TDC of the compression stroke of the reference cylinder.
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Wiring Diagram
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Single Cylinder Dropout Test
The ignition has the ability to run briefly without firing a single cylinder. This can be used to verify that each cylinder is supplying a similar amount of power to the engine.
WARNING:
Running without firing one cylinder sends unburnt fuel to the catalyst, which is hard on the element. Cylinder dropout tests should only be run briefly, with plenty of time between tests running normally to make sure unburnt fuel is purged out of the system. The test should be used with a moderate load, if the load is too high the engine will probably stall.
The single cylinder dropout test screen is found by navigating from the ignition home page to "Setup and Testing", "Testing Pages" category, then "Single Cyl Dropout Test". To use this test, an EIM version of 2.00 or higher and an ignition version of 1712 or higher are required.
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Single Cyl Dropout Test Screen (Shown during test)
Manual Test
Once the engine is running, a manual test can be used by clicking 'Manual Drop One Cylinder'. A dialog will be shown to choose a cylinder, after which the engine will run without firing that cylinder for about 5 seconds. After the test the average RPM and manifold pressure during the test will be shown.
During the test, selecting 'Stop Test' will abort the test.
Auto Test
If an EMIT governor is present on the engine, the 'Auto' test can be used. The ignition will perform the following sequence during this test:
- The governor will be commanded to hold a fixed throttle position, followed by a short delay
- Each cylinder will be dropped out for about 4 seconds each
- At the end of the test, the governor and ignition will return to normal operation
During the test, the test can be stopped by selecting 'Stop Test'. Also, if the engine stops during the test it will be aborted.
After the test, a graph of the RPM and MAP during the test will be shown. (Note: A MAP sensor can be connected to the ignition, governor, or AFRC to get MAP information). This makes comparing cylinder power easy.
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Since the throttle is fixed during the test, the RPMs will change based on how much power is lost as each cylinder is dropped. If one cylinder in particular has a higher engine speed during its dropped period, this means that the cylinder was doing less work than the average of the others. This could be due to poor combustion (plug, ignition, etc.) or poor compression (valves, etc.).
