1. 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.^[1] Since Dec. 2010 discussion moved to the forum on diyefi.org.^[2] In 2013 own project's forum had been opened.^[3] The system has evolved from the ignition control to the engine management system (ECU). The project is supported by author all the time.

2. 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:

• Simultaneous (all injectors open at the same time), central (throttle-body) injection, two banks alternating (two injectors or two banks of injectors fire alternately) and semi-sequential injection (injectors fire by pairs). In the nearest future full-sequential injection support will be added
• Speed-density method of estimating airflow into an engine (MAP and IAT sensors are used)
• Open-loop IAC (closed-loop algorithm (PID) will be implemented in the nearest future)
• Closed loop control of AFR using oxygen sensor. Ability to set voltage threshold, integrator step etc.
• Tables: VE, AFR, inj.open time, warm up enrichment, IAC position on cranking, IAC position vs coolant temperature, inj.time on cranking, inj.timing
• After start enrichment
• Acceleration enrichment (TPS, RPM)
• Priming pulse (wetting of intake manifold) vs coolant temperature

3. 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).

4. Features

• Support of engines with the following number of cylinders: 1, 2, 3, 4, 5, 6, 8
• Synchronization from CKP sensor and missing tooth wheel or from two sensors and non-missing tooth wheel. Support of 60-2, 36-1 and other wheels with different number of teeth (from 16 to 200)
• Synchronization from Hall sensor (the distributor can be left in the system)
• Advance angle regulation from engine speed (from 1 VR sensor, 2 VR sensors or Hall sensor)
• Advance angle regulation from engine load (from MAP sensor)
• Correction of advance angle depending on temperature (various types of coolant temperature sensors)
• Correction of advance angle from detonation (from 1 or 2 knock sensors)
• Measurement of on-board electric system voltage
• Idle cut-off valve solenoid control
• Control of power valve solenoid (part load enrichment valve)
• Multichannel output (from 1 up to 6 igniters). It is possible to use up to 8 channels!
• Support of 2 channel igniters (single input driven by both edges)
• RS-232 interface for reprogramming, control and tuning (with optical isolation) or USB interface (without optical isolation)
• Able to control of engine cooling fan (use of PWM is also supported)
• Starter blocking when engine speed reaches specified value
• Gas equipment support (automatic switch between gas/gasoline modes)
• Output for error indication “Check Engine” with support of blink codes
• Ability to emergency start of boot loader
• Ability to recover settings in emergency case
• Idle speed regulation using advance angle
• Control of coil energy accumulation (dwell control)
• Cam sensor support (coil per cylinder – full sequential ignition)
• Fuel injection control (central, simultaneous injection)
• Injection timing control using custom fuel map
• Calculation of air flow using Speed-Density method
• AFR control on carburetor (Solex) by means of valve actuators with closed loop (oxygen sensor)

Additional features:

• Control of an electric fuel pump
• Tunable pulses output for Hall sensor or tachometer
• Embedded stroboscope function (it is possible to use any free output)
• Output and input functions remapping
• Determine throttle gate position by TPS sensor
• Processing and writing to log file signals from 2 additional inputs (e.g. Oxygen sensor can be connected)
• Power management (ability of some functions to work after ignition is switched off, for instance working off cooling fan or auto choke control)
• Carburetor choke control (using a stepper motor)
• Stepper gas valve control
• Support of speed sensor (Displaying and writing to log vehicle speed (km/h) and passed distance (km))
• Control of manifold heater (also known as grid and intake heaters)
• Correction of advance angle using air temperature sensor (connected to one of 2 additional inputs)
• 3 versatile programmable outputs, which can be programmed by user to perform different actions in very convenient and flexible way

5. Version Differences