Introduction
How does the Haltech Interceptor Work?
All factory ECUs will have a sensor used to calculate engine load, and a sensor used to track engine position.
The engine load sensor (in order of highest to lowest preference) is usually an airflow meter (AFM), a manifold absolute pressure (MAP) sensor, or a throttle position sensor (TPS). Some engines may have all of these sensors, but the lower preference sensors are used for diagnostics or transient fuel calculations, and have no effect on the calculated engine load. These sensors usually output 0 － 5V analogue voltage or a frequency voltage signal that the factory ECU uses to calculate engine load. This engine load is then used to calculate how much fuel to inject into the engine.
Fuel Control
When installing the Haltech Interceptor, the signal wire from the engine load sensor to the ECU is cut and rewired so that the sensor signal output goes into the Haltech Interceptor. The Haltech Interceptor then produces a new signal that is connected to the ECU input for the sensor. The interceptor can now make changes to the load signal of the engine so that the factory ECU thinks that the engine load is different to what it actually is.
The factory ECU has tables inside its memory that are used to calculate the required injection time to achieve the desired fuel mixture at various engine load and RPM sites. By altering the engine load signal, the interceptor can alter the position in the tables that the factory ECU is using to calculate the injection time. Generally it is possible to enrich the fuel mixtures by increasing the engine load signal, and to lean the fuel mixtures by reducing the engine load signal.
Inside the Haltech Interceptor is a memory that retains its data even when the interceptor is turned off. Within this memory is a table of percentages that are mapped against engine RPM and engine load. The interceptor calculates the engine RPM and load, and then extrapolates a percentage out of the table that it can apply to the input load signal to produce an output signal altered by this percentage. The tuner of the Haltech Interceptor can tune the percentage tables to output an altered signal that results in the factory ECU thinking the engine load is different to the actual engine load and changing its injection time to achieve the desire fuel mixture ratio across various engine load and RPM.
Ignition Control
The engine position sensor is usually a Hall effect or Reluctor type sensor that is fitted to detect teeth, slots, or magnets on the crankshaft or camshaft of the engine. The factory ECU uses the signal produced by this sensor to calculate engine speed and position, and using this information, it can generate pulses that result in a spark at the desired ignition advance angle.
When installing the Haltech Interceptor, the signal wire from the engine position sensor to the ECU is cut and rewired so that the sensor signal output goes into the Haltech Interceptor. The Haltech Interceptor than produces a new signal that is connected to the ECU input for the sensor. The Haltech Interceptor can then alter the phasing of this signal to advance or delay the signal on its output relative to the true engine position. The result of this is that the factory ECU thinks the engine is in a slightly altered position to the actual position, and therefore it will produce its ignition spark advance output at a similarly altered position.
The Haltech Interceptor contains another table that works in a similar fashion to the table used for altering the engine load sensor described above. The tuner edits this table to provide ignition corrections over various engine load and RPM sites. The interceptor alters the engine position signal by the amount it extrapolates from the table. In this way the tuner can optimally tune the engine to the desired ignition timing.
By intercepting the engine load and position sensors, the Haltech Interceptor can accurately control the factory ECU to deliver the optimal ignition time and fuel mixtures for all engine load and RPM conditions.
In addition to fuel and ignition tuning, there may be other engine signals that can be used to alter engine performance. The Haltech Interceptor has been designed to allow the control of many engine components for optimal performance such as turbo boost pressure and variable cam timing. Additionally, the Haltech Interceptor can be used to override factory protection features like speed limiters and boost limiters.
The Haltech Interceptor is designed to work in perfect unison with the complex factory ECUs on modern cars. It works as a package to provide control of all performance parameters, as well as defeat unwanted protection features of the factory ECU.