SECU-3

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SECU-3 project logos SECU-3 TM Logo.png
SECU-3 project logos
SECU-3T revCU6 USB with MAP SECU-3T revCU6 USB+MAP angle.jpg
SECU-3T revCU6 USB with MAP

SECU-3 [1] is an internal combustion engine control unit. It is being developed as an open source project (drawings, schematic diagrams, source code etc. are open and freely available for all). Anyone can take part in the project, and can access all the information without any registrations.

Contents

SECU-3 system controls the ignition, fuel injection and various other actuators of the internal combustion engine (ICE) and vehicle. In particular, it is capable of controlling the carburetor choke using a stepper motor (auto choke), thus controlling RPM when engine is warming up. SECU-3 manages AFR on the carburetor engines (similar to AXTEC AFR systems), idle cut-off valve and wide open throttle mode valve in carburetor systems, controls electric fuel pump and gas valves in closed loop mode according to the feedback from the oxygen sensor. The SECU-3 system provides unique opportunities for reassigning the I/O pins of the mainboard for custom uses in engine tuning. It also provides smooth speed control of the engine electric cooling fan. The system includes its own software which allows editing all major settings and fuel and ignition maps in real time (when the engine is running), and switching between 2 or 4 sets of maps. SECU-3 system has many other advanced features (listed below).

Currently, there are five modifications of the unit:

  1. SECU-3. The first version of the unit, developed in 2007, controls ignition, cooling fan and has some other functions. In the latest software releases, the support for this unit had been discontinued. History of the SECU-3 versions with photos could be accessed here
  2. SECU-3T. [2] It can control the ignition and fuel injection. It does not contain built-in power drivers for ignition coils, fuel injectors and idling air control (IAC) valve. External drivers must be used.
  3. SECU-3L. [3] It was designed for ignition control only and it can be considered as a light version of the SECU-3T unit. However, it contains built-in drivers for ignition coils, as well as manifold absolute pressure (MAP) sensor. Regarding the software, it is fully compatible with the SECU-3T unit.
  4. SECU-3 Micro. [4] Very easy-to-use and low-cost ignition controller unit in small plastic enclosure. Has only few inputs and outputs and doesn't contain built-in power drivers for ignition coils. It is the simplest SECU-3 unit.
  5. SECU-3i. [5] Full-featured, complete engine management system in metal enclosure with integrated power drivers (for ignition coils, injectors, IAC actuator etc.), with extended number of I/O and Bluetooth connectivity. The latest development of the system. This unit has double-board design.

The device is developed using the 8-bit AVR microcontroller ATMega644, with 64kB memory (ROM), 4kB random access memory (RAM), and operates at a clock frequency of 20 MHz. It includes analog and digital inputs, separate chip for preprocessing signal from the knock sensor (KS) (except SECU-3 'Lite' and 'Micro' units), a signal conditioner for VR start-pulse sensor (except SECU-3 Micro unit), a signal conditioner for the VR crankshaft position sensor (CKP), the interface with a computer, and the outputs for actuators control.

Structural diagram of the system with SECU-3T unit:

Example of wiring diagram of the SECU-3T unit for controlling of fuel injection Secu3t wiring inj hi-z stepper1.png
Example of wiring diagram of the SECU-3T unit for controlling of fuel injection
SECU-3 Manager v3.4 - first tab Secu3man-pm-v34-en.jpg
SECU-3 Manager v3.4 - first tab

Structural diagram of the system with SECU-3L unit is shown on the following picture: Structural diagram of the system with SECU-3 Micro unit: Example of wiring diagram of the SECU-3T unit for controlling of simultaneous or semi-sequential fuel injection on the 4-cylinder engine is shown on the picture below. Hi-z injectors and stepper IAC valve are used. On the right side of picture we can see external connector functions which should be remapped to specified values. It is done in the SECU-3 Manager software.

Example of wiring diagram of the SECU-3T unit for controlling of simultaneous or semi-sequential fuel injection. Hi-z injectors, stepper IAC Secu3t wiring inj hi-z stepper1.png
Example of wiring diagram of the SECU-3T unit for controlling of simultaneous or semi-sequential fuel injection. Hi-z injectors, stepper IAC

History

The first version of SECU-3 was launched in October 2007 and successfully works on the author's (A.Shabelnikov) vehicle for now. Since then, the project has received a lot of new features and synchronization methods. First discussing of the project was started in 2007 in one topic on the iXBT conference. [6] Since Dec. 2010 discussion moved to the forum on diyefi.org. [7] In 2013 own project's forum had been opened. [8] The system has evolved from the ignition control to the engine management system (ECU). The project is supported by author all the time.

Current status

Continue to develop and extend fuel injection features and algorithms (inter alia, full-sequential injection support). Also, author works on software for the SECU-3i unit.

Features of the current firmware related to fuel injection:

License

GPL, TAPR OHL with one addition: developments can not be used in commercial purposes without written approval of author (according to information from the official site).

Features

Additional features:

Version differences

SECU-3SECU-3TSECU-3T revC and laterSECU-3L (Lite)SECU-3 MicroSECU-3i
Date200720122014201520162016
MCUATmega16, ATMega32ATMega32ATMega644ATMega644ATMega644ATMega644
Features Wasted spark, synchronization from CKP sensor full-sequential ignition,

synchronization from Hall sensor, CKP sensor, CKP + reference sensor, automatic control of carburetor's choke, immobilizer with iButton key, optional embedded bluetooth

same, plus fuel injection control,

AFR control on carburetor, stepper gas valve control, programmable outputs

Lite version, intended for ignition control and two additional outputs.

Simplified installation and wiring. Ignition coil drivers integrated to the unit.

Maximum simplified version, intended only for ignition control. Has only two ignition outputs and several inputs.

Simplified installation and wiring.

The most functional version among SECU-3 units, a full EMS. All the necessary devices are built into the unit (drivers for injectors, ignition, IAC, stepper motor, PWM etc.).

The unit consists of two boards, has optional embedded Bluetooth.

Main connector DB-25 MiniFit 24 pinMiniFit 14+12 pinMiniFit 14 pinMiniFit 12 pinMiniFit 24+6+14+12 pin
Interface RS-232 with optical insulation RS-232 with optical insulation or USB USB Insulated USB USB Insulated USB

Related Research Articles

Fuel injection Feature of internal combustion engine

Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and rotary piston engines.

A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process.

Chrysler LA engine Motor vehicle engine

The LA engines are a family of pushrod OHV small block 90° V-configured gasoline engines built by Chrysler Corporation. It was factory-installed in passenger vehicles, trucks and vans, commercial vehicles, marine and industrial applications from 1964 through 1991 (318) & 1992 (360). The combustion chambers are wedge-shaped, rather than the polyspherical combustion chambers in the predecessor A engine or the hemispherical combustion chambers in the Chrysler Hemi engine. LA engines have the same 4.46 in (113 mm) bore spacing as the A engines. LA engines were made at Chrysler's Mound Road Engine plant in Detroit, Michigan, as well as plants in Canada and Mexico. The "LA" stands for "Light A", as the older "A" engine it was closely based on was nearly 50 pounds heavier. Willem Weertman, who later became Chief Engineer – Engine Design and Development, was in charge of the conversion. The basic design of the LA engine would go unchanged through the development of the "Magnum" upgrade (1992-1993) and into the 2000s with changes to enhance power and efficiency.

MegaSquirt is a general-purpose aftermarket electronic fuel injection (EFI) controller designed to be used with a wide range of spark-ignition internal combustion engines MegaSquirt was designed by Bruce Bowling and Al Grippo in 2001.

Lean-burn refers to the burning of fuel with an excess of air in an internal combustion engine. In lean-burn engines the air:fuel ratio may be as lean as 65:1. The air / fuel ratio needed to stoichiometrically combust gasoline, by contrast, is 14.64:1. The excess of air in a lean-burn engine emits far less hydrocarbons. High air–fuel ratios can also be used to reduce losses caused by other engine power management systems such as throttling losses.

Manifold vacuum, or engine vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere.

Back-fire Explosion in the exhaust of an engine

A backfire or afterburn is combustion or an explosion produced by a running internal combustion engine that occurs in the exhaust system, rather than inside the combustion chamber. It is also sometimes referred to as an afterfire, especially in cases where the word backfire is used to mean a fuel burn that occurs while an intake valve is open, causing the fire to move backward through the system and out through the intake instead of the exhaust. When the flame moves backward it may also be called a "pop-back." A backfire can be caused either by ignition that happens with an exhaust valve open or unburnt fuel making its way in the hot exhaust system. A visible flame may momentarily shoot out of the exhaust pipe. A backfire is often a sign that the engine is improperly-tuned.

MAP sensor

The manifold absolute pressure sensor is one of the sensors used in an internal combustion engine's electronic control system.

Engine control unit Computer that adjusts electronics in an internal combustion propulsion system

An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by reading values from a multitude of sensors within the engine bay, interpreting the data using multidimensional performance maps, and adjusting the engine actuators. Before ECUs, air–fuel mixture, ignition timing, and idle speed were mechanically set and dynamically controlled by mechanical and pneumatic means.

Motronic

Motronic is the trade name given to a range of digital engine control units developed by Robert Bosch GmbH which combined control of fuel injection and ignition in a single unit. By controlling both major systems in a single unit, many aspects of the engine's characteristics can be improved.

A throttle is the mechanism by which fluid flow is managed by constriction or obstruction.

Ignition timing

In a spark ignition internal combustion engine, Ignition timing refers to the timing, relative to the current piston position and crankshaft angle, of the release of a spark in the combustion chamber near the end of the compression stroke.

Renix was a joint venture by Renault and Bendix that designed and manufactured automobile electronic ignitions, fuel injection systems, electronic automatic transmission controls, and various engine sensors. Major applications included various Renault and Volvo vehicles. The name became synonymous in the U.S. with the computer and fuel injection system used on the AMC/Jeep 2.5 L I4 and 4.0 L I6 engines.

Digifant engine management system

The Digifant engine management system is an electronic engine control unit (ECU), which monitors and controls the fuel injection and ignition systems in petrol engines, designed by Volkswagen Group, in cooperation with Robert Bosch GmbH.

Trionic T5.5 is an engine management system in the Saab Trionic range. It controls ignition, fuel injection and turbo boost pressure. The system was introduced in the 1993 Saab 9000 2.3 Turbo with B234L and B234R engine.

Trionic is an engine management system developed by Saab Automobile, consisting of an engine control unit (ECU) that controls 3 engine aspects:

  1. Ignition timing,
  2. Fuel injection
  3. Acts as a boost controller.
Crankshaft position sensor

A crank sensor is an electronic device used in an internal combustion engine, both petrol and diesel, to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control the fuel injection or the ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on petrol engines.

Internal combustion engines come in a wide variety of types, but have certain family resemblances, and thus share many common types of components.

Modular Engine Management System

The Modular Engine Management System, or MEMS, is an electronic control system used on engines in passenger cars built by Rover Group in the 1990s. As its name implies, it was adaptable for a variety of engine management demands, including electronically controlled carburetion as well as single- and multi-point fuel injection. The abbreviations "SPi" and "MPi" refer to the single-point and multi-point injection configurations, respectively.

References

  1. ↑ "Engine Management System SECU-3 / Spark Advance Controller Secu-3".
  2. ↑ Shabelnikov, A.A. (2015). "Electronic control unit for internal combustion engine SECU-3". Visnik Nacional'nogo Tehnichnogo Universitetu "HPI". Kharkiv Polytechnic Institute. 156 (22): 90–95.
  3. ↑ Shabelnikov, A.A. (2015). "Ignition control system for internal combustion engines SECU-3L (Lite)". BULLETIN OF THE NATIONAL TECHNICAL UNIVERSITY "KHARKIV POLYTECHNIC INSTITUTE" Series: "New Solutions in Modern Technologies". Kharkiv Polytechnic Institute. 155 (46 (1155) 2015): 115–121.
  4. ↑ Alexey Shabelnikov (2016). "MICROPROCESSOR CONTROLLED IGNITION SYSTEM SECU-3 MICRO". Materiały Xii Międzynarodowej Naukowi - Praktycznej Konferencji Aktualne Problemy Nowoczesnych Nauk - 2016. Sp. z o.o. «Nauka i studia». 111: 55–61.
  5. ↑ Shabelnikov, A.A. (2016). "SECU-3i PROGRAMMABLE ENGINE MANAGEMENT SYSTEM". Technology, Energy, Agriculture Transport AIC. Vinnytsia National Agrarian University. 112 (2(94)): 67–73.
  6. ↑ "Регулятор угла опережения зажигания на микроконтроллере. [1] - Конференция iXBT.com". forum.ixbt.com.
  7. ↑ "DIYEFI.org Forum - SECU-3 Archive". forum.diyefi.org.
  8. ↑ "SECU-3.org - Index page". secu-3.org.
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