SDS EIC Installation Manual
Version 1.2 12/04
The SDS EIC is a microprocessor-based, digital unit designed to control either two or four supplemental injectors independently from the normal engine management system. The EIC has a control knob to adjust the boost threshold point where fuel will start to be injected and a Gain knob to adjust the amount of fuel delivered. RPM and manifold pressure inputs allow proportional increases in fuel delivery as these two parameters increase.
** Please read the entire manual before beginning hookup and operation. **
Theory of Operation
RPM and manifold pressure (MAP) readings are fed to the EIC microprocessor which then takes into account the MAP Threshold knob position and the fuel Gain knob position to determine the appropriate injector on-time. The microprocessor generates a square wave control signal to the injector control transistors of the proper frequency to achieve this desired on-time. Five colored LEDs display injector cut on and duty cycle performance.
System Hookup and Mounting
The basic EIC box is designed to be mounted under the dash using the tabs provided, close to the driver and shielded from direct sunlight for the best LED viewing. Hookups on the control unit are as follows:
Red to switched +12 volts
Green to tachometer lead or negative side of ignition coil
2 Blacks to separate chassis ground points at least 4" apart
Vacuum Hose to intake manifold or plenum downstream of the throttle plate
Injector connections are as follows:
2-wire plug from control unit plugs into 2-wire injector harness plug
4-wire plug from control unit plugs into 4-wire injector harness plug
Red wire on injector harness goes to switched +12 volts
On installations where the intake plenum volume is small and/or the vacuum hose connection is short, it may be advisable to put a .030" to .040" orifice in the hose. This will help smooth out pressure spikes to the MAP sensor.
Injector Placement and Substitution
Make sure you use the correct impedance injectors for your controller model. The controller will have separate gold resistors in the harness if it's set up to drive low impedance injectors and will have none if set up for high impedance ones.
The two-injector model is designed to control two additional injectors mounted ahead of the throttle body or in the intercooler outlet pipe. On naturally aspirated engines where this mounting position is impossible, injectors may have to be mounted on the intake plenum.
Positioning and orientation of the injectors may have an important effect on cylinder-to-cylinder fuel distribution. Modern fuel-injected engines have manifolds designed to conduct only dry air. When atomized fuel is introduced, poor mixture distribution can result. This can result in some lean cylinders with consequent engine damage. This can be especially prevalent on installations where the injectors are mounted on the manifold. However, when the injectors are mounted ahead of the throttle body, air and fuel are given extra time to mix before entering the cylinders. This generally leads to better cylinder-to-cylinder distribution.
The four-injector model is designed to control one injector per cylinder on a four-cylinder engine. When the injectors are mounted in the runners near the port, excellent fuel distribution will result. Injectors should be mounted at least half way down the intake runners. Mounting closer to the port will ensure that all of the injected fuel goes into that cylinder. Mounting injectors too far away from the ports may introduce poor mixture distribution during valve overlap period due to blow-back effects. On many engines, the EIC injectors may have to be mounted on the bottom of the intake runners.
Be sure to select injectors with sufficient flow to support the desired hp increase over stock. We can assist you with sizing.
An electric drill and die grinder can be used to perforate the area for injector boss mounting. A hole about 3/8" should be made initially. This can be enlarged with bigger drills or with the die grinder. An elongated hole is usually desirable when mounting the 45° bosses. Ensure that the injectors have some lateral clearance in the hole before welding. Bosses should be carefully placed and clamped before being TIG-welded into position. Carefully remove all chips and debris from the assembly before installing.
Fuel connections from the injectors bosses to the fuel rail area are made with the 1/8 NPT fittings and high pressure hose. A METAL tee may be placed in the pump to rail line or, alternately, the fuel rail can be tapped for fittings and the connections made at the rail directly. The fuel pump should be powered up before running the engine to verify that there are no leaks. Be sure to use hose and fittings compatible with fuel and the pressures involved. Check all connections before powering up the pump. Inadequate materials can lead to a serious fire.
When powered up, all five LEDs will illuminate for two seconds to verify LED function. The left knob, Threshold, is used to set the turn-on point for the injectors. It is graduated on the left side in inches of mercury vacuum and on the right side in pounds per square inch boost. Software limits prevent setting the threshold point below 12" of vacuum. To have the EIC injectors turn on at 5 psi, for instance, you would set the Threshold knob at about the straight-up position. Verify the turn-on point with the' on' LED and your boost gauge.
The right knob, Gain, is used to set the amount of fuel injected. Turning the knob clockwise increases the amount of fuel injected. Software limits do not allow fuel to be injected below 200 rpm on 4 cylinder engines, 1333 rpm on 6 cylinder engines and 1000 rpm on 8 cylinder engines.
The green LED illuminates when the EIC starts injecting. The three yellow LEDs indicate injector duty cycle in 25% increments. The red LED indicates that 100% duty cycle has been reached at 22 psi. Rpm enrichment continues to 15,000 rpm on a 4 cylinder, 10,000 on a 6 cylinder and 7,500 on an 8 cylinder.
Setup of Naturally Aspirated Engines
On naturally aspirated engines, the Threshold knob should usually be adjusted to around the 5" range.
Setup on Engines which were Originally Naturally Aspirated, but are now Supercharged or Turbocharged and are Fitted with Speed/Density type Stock EFI Systems
0 is usually the best Threshold knob setting for this application. Since a naturally aspirated speed density system cannot read when the engine is under boost, it stops putting in extra fuel when the MAP sensor reads atmospheric pressure. By turning the Threshold knob to 0, you ensure that the EIC takes over supplemental fuel control right where the stock system leaves off.
Setup on Engines which were Naturally Aspirated, but are now Supercharged or Turbocharged and are Equipped with a Mass Airflow Type Stock EFI System
Theoretically, the best Threshold knob setting for this application would be at the boost pressure where the stock injectors reach 100% duty cycle. This can be difficult to determine by feel. We highly recommend that a mixture meter be used for setup. For most of these applications, the Threshold knob will be set in the 5-10 psi range.
Setup on Factory Turbocharged Engines running higher than Stock Boost (Speed Density and Mass Airflow)
In these cases, the Threshold knob is usually best set at the boost pressure where the stock injectors reach 100% duty cycle, or the point at which the Stock MAP or MAF sensor is incapable of measuring any further increases in boost or airflow, whichever occurs first. It should be noted that many stock EFI systems have a fuel cutoff to protect from overboosting. If your system has this feature, it must be disabled to run higher boost pressures.
A mixture meter is highly recommended to find the point at which the factory fuel system ceases to enrich the mixture. Bringing in EIC operation too late can cause a lean bump in the mixture curve, as the factory injection trails off fuel delivery. This can cause engine damage. Bringing the EIC in early may cause the mixture to be too rich just before the stock injection falls off. The latter is a safer condition.
The Gain control should be carefully set to allow smooth engine performance throughout the whole rev and boost range. We recommend that you start with the Gain knob in a very rich or clockwise position. The engine will usually misfire when the EIC comes on with this setup. The Gain knob may be turned slowly counter-clockwise until the misfire just disappears. Remember, clockwise gives more fuel. Note that severe engine damage can result if the mixture becomes too lean. We highly recommend that a mixture meter be used for the EIC setup. Once satisfactory operation has been achieved, no further adjustments should be needed.
Understanding Injector Duty Cycle
The duty cycle LEDs are for a rough guide as to how much fuel is being injected. Depending on the application, understand that you do not need to see all of the LEDs lit at full throttle. Some applications will use only a fraction of the injector flow capacity available to achieve proper mixture ratios.
Duty cycle refers to the amount of time the injector remains open in relation to how much time is available at that rpm before the next injection cycle begins. As rpm rises, the amount of time available to inject decreases. Therefore, at a given pulse width, the duty cycle rises as rpm increases. Once 100% is reached, the injectors are spraying continuously and this is the point of maximum fuel delivery.
The SDS EIC injects fuel in alternating pulses to ensure that there is no null time which could lead to an uneven fuel delivery condition. For every tachometer pulse, there is a fuel pulse.
On a two-injector system, two injectors MUST be used. On a four-injector system, four injectors MUST be used.
Fuel Pump and Fuel Pressure
It is important to ensure that the fuel pump output and pressure is sufficient to feed both systems at full power with the increased fuel flow. A fuel pressure gauge may have to be fitted to verify this.
Technical questions may be directed to your dealer, or to:
All SDS software and PCB design is the exclusive property of Simple Digital Systems. Unauthorized use or reproduction is a violation of copyright.