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● Injector

１１１１．．．． Injector Sizing

Injector sizing is determined by the amount of horsepower the engine will be producing.

Injector sizing is measured in cc/min. (cubic centimeter/minute)

For 6 cylinder motors, a general rule of thumb is 1 horsepower needs 1 cc/min of fuel. It is always

best to calculate from overall injector volume. One horsepower needs 6cc/min total fuel volume

from all of the injectors.

For example, to achieve 100 horsepower, a 6 cylinder engine must have 100 cc/min injectors. For

a 4 cylinder vehicle to achieve 100 horsepower, it needs 150cc injectors.

（Calculating method）

100(hp) × 6(cc) ＝ 600(cc/min)・・・Total injector volume required.

600(total cc) ÷ 4(cyl #) = 150(cc/min)・・・Single injector volume required.

※ Since there is a small difference even in the same injector size, the fuel delivery may become

unstable when it is at 100% duty cycle. It is recommended to have a large enough injector so

the injector is not maxed out.

※ It is not always good to use a very large injector. The injector lag time may increase and fuel

atomization may not be good either. Sometimes having too large of an injector may cause bad

drivability as well.

２２２２．．．． Fuel Pump Sizing

Fuel pump size selection depends on large the injectors will be.

The fuel pump size will be measured in l/h (liter/hour)

（Calculation method）

600(cc/min)×60÷1000 = 36（l/h）・・・Necessary fuel pump size.

※ Even same brand fuel pumps may have differences in fuel pressure so it is always a good idea

to use a fuel pump with a little extra volume.

※ If the fuel pump is too large, the fuel return may not be large enough to relieve the fuel pressure.

This may cause an increase in fuel pressure and damage the fuel pump.

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３３３３．．．． Injector Lag Time

The injector will operate (open) when the power coming from the battery is grounded through the

ECU.

①

The time it takes from when the ECU grounds the injector circuit to actually delivering fuel

through the injector is called Injector Lag Time.

Lag time is not affected by RPM., but by the load that is put on the engine. The lower the load is

on the motor, the larger the lag time will be.

① Scope Pattern

４４４４．．．． Injector Duty Cycle, Injector Duration

The injector duty cycle is the amount (in percentage) that the injector is open during one engine

cycle.

（Calculation Method）

Time of 1 engine Cycle（2 crank revolutions）＝ 2×60×1000 ÷ Engine RPM

Duty Cycle ＝ Duration ÷ time of 1 cycle（2 crank revolutions）

If the duration of the injector remains the same while RPM increases, the duty cycle will increase

because the time of 1 engine cycle will decrease. Peak torque RPM and where charge efficiency is

at its highest is where injector duration will be longer.

５５５５．．．． Fuel Pressure

Fuel pressure is a measurement of how much pressure is inside the fuel delivery system.

Generally the fuel pressure is between 2.5~3.5kg/cm2 (35~50PSI) on most vehicles. Fuel pressure

is adjusted by the fuel pressure regulator, which can be attached to either fuel rail or fuel pump.

Aftermarket fuel pressure regulators make it possible to adjust the fuel pressure. At any given

injector duration, if the fuel pressure rises, it will deliver more fuel. If the fuel pressure drops, the

amount of fuel delivered will decrease.

（Calculation method）

Pres. After change

Pres Before change

※ If you raise the fuel pressure too much, you will risk damaging the fuel pump. It is best to

stay under 5.0 kg/cm2 (71 PSI) of fuel pressure.

×Injector flow rate before modification＝ New injector flow rate

I/J

ＥＣＵ － ＋

Battery

Injection time Lag Time

“ON” Time

12V

0V

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● Air Fuel Ratio

１．Air Fuel Ratio

With gasoline engines, oxygen must mix with the proper amount of fuel, compress, and burn to

create energy. Gasoline is a chemical compound of hydrogen and carbon. Combustion of fuel and

air will change the condition of the oxygen and carbon dioxide in the air. At the time of

combustion, the gasoline will burn completely at a ratio of 1 to 14.7. This is called Stoichiometric

or Theoretical Combustion.

The air fuel ratio is determined by the mass of air and fuel.

A F/ Ratio 9 10 11 12 13 14 15 16 17 18 19 20

２．Air fuel ratio for horsepower

The air fuel ratio in which horsepower will be greatest is usually around 12.5-13 to 1.

３．Air fuel ratio for economy

The air fuel ratio in which fuel economy will be best us usually around 18 to 1.

４．Fuel Cooling

For turbo charged vehicles, the engine will become very hot when in operation, which will make the

oil not lubricate as effectively and also make the motor work less effectively. With the motor

running at such high temperatures, the fuel will evaporate and cool the intake charge. Fuel cooling

is most effect at an air fuel ratio of 10.5~11.0 to 1.

Pistons with cooling channels are designed to prevent detonation and will allow you to raise the air

fuel ratio to 11.0~11.5 to 1. For any other type of turbo vehicle, it is best to stay around 10.5~11.0

to 1 air fuel ratio.

※ Be careful not to lean the fuel mixture too much or retard the ignition too much because this

will cause the exhaust temperature to rise and may cause engine damage.

※ Please also pay attention to oil deterioration/dilution due to rich fuel mixture conditions.

Power

Fuel consumption

Stoichiometric

Combustion

Peak Power

Peak efficiency

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● Ignition

１．Ignition Systems

◎ Distributor Type

ECU has one channel output to control the igniter. The number of cylinders will be how

many times the ECU will activate the igniter in one engine cycle. For a four cylinder engine,

one channel will fire four spark plugs.

※ On some vehicles, the igniter is inside the ECU. This type of ignition system is not

compatible with the e-manage ignition control system.

◎ Wasted Spark Type

The ECU is equipped with one ignition output channel per two cylinders. Each ignition

channel will be activated twice per engine cycle. For a four cylinder engine, two channels

fire two spark plugs.

◎ Direct Ignition (Coil-On-Plug)

The ECU is equipped with one ignition output channel per cylinder. Each ignition channel

will be activated once per engine cycle. For any cylinder engine, one channel will fire a

single spark plug individually.

２．Normal Combustion, Ignition Lag

There are three stages to normal combustion. Nucleus of flame: Ignition spark jumps gap of plug,

causing a small flame in the gap. Hatching out: Nucleus is torn apart and fingers of flame spread

though fuel mixture. Propagation: Flame spreads across combustion chamber evenly and causes a

sharp rise in pressure and temperature.

Fuel does not completely burn immediately after the spark plug ignites. The time it takes for the

ignition spark to become a nucleus of flame is called Ignition Lag. Ignition Lag will generally

depend on the amount of incoming air and fuel. RPM does not really directly affect the ignition

lag.

Flame propagation will be quicker at higher RPM. If RPM is lower and there is high load on the

motor, the air and fuel charge will be greater, resulting in quicker propagation as well.

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３．Max Combustion Pressure

Generally, gasoline engine will work most efficiently if the max combustion pressure is around

10~15 degrees ATDC. Since the gasoline may burn at different rates depending on the conditions of

operation, the ignition timing will need to be adjusted properly for the combustion pressure to be

highest at 10~15 degrees ATDC.

４．Ignition Timing

Generally, ignition timing is set for the spark plug to ignite just before Top Dead Center.

Generally, with a constant load, ignition timing will advance as RPM increases. With constant

RPM, ignition timing will retard as load increases.

５．Differences in Vehicles

Since Subaru Engines have larger cylinder bores, flame propagation takes longer so the ignition

timing must be more advanced.

Since Mitsubishi engines have smaller cylinder bores, flame propagation takes less time so the

ignition timing will be less advanced.

Plug Ignites

Pressure

Ignition Lag

Propagation

Crank Angle

TDC

ATDC10～15°

Peak Combustion

Pressure

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６．Detonation

In a normal condition, the plug will ignite the fuel and the flame will propagate from there. When

the compression ratio is too high, ignition timing is too advanced, or air fuel ratio is too lean, the

air-fuel mixture will self ignite in the propagation stage.

When it self ignites, the flame propagation is uncontrollable and much quicker than normal

combustion. Detonation will usually come with a knocking or rattling sound from the engine.

※ The reason aluminum parts do not melt when exhaust temperatures are above 1500℃ is

because a layer of air is formed during combustion that protects these parts. Detonation will

break this layer so the parts are not protected anymore and the extreme heat will be in direct

contact with the engine parts, making them easier to break.

７．Pre-ignition

Pre-ignition is when the air-fuel mixture ignites before the spark plug. Under normal condition, the

fuel will ignite after the spark plug is ignited, but under extremely high temperatures, the fuel

mixture will self ignite. Pre-ignition is easy to occur when the spark plug electrode tip reaches

900℃ (1650F). By raising the spark plug coldness number by 1, the temperature of the electrode

tip will drop 30-50℃ (85-120F) and help prevent pre-ignition.

Pre-ignition will cause much more damage to the engine that has detonation. Pre-ignition can

blow a motor in an instant and is usually the cause of having a hole in the piston. It is important

to prevent pre-ignition as much as possible.

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● Air Flow

１．Air flow volume calculation

Different devices, sensors, and calculation methods are used so the ECU can determine the amount

of air that is being sucked into the motor. With the amount of air calculated, the ECU will

calculate the amount of fuel that is necessary and operate the injectors to deliver the proper amount

of fuel.

Air flow volume is generally measure in two ways, directly and indirectly. Direct measurement

types are called mass air flow meters (L Jetronic). Indirect measurement methods use speed

density and throttle speed.

◎ Mass Air Flow（L Jetronic）

Generally called L Jetro, the air flow volume is measured with an airflow meter. With this

measurement at a given RPM, the proper fuel amount needed can be calculated.

◎ Speed Density

Generally call D Jetronic, the air flow volume is calculated from manifold pressure. With this

measurement at a given RPM, the proper fuel amount can be calculated, but it is not as accurate

as the L Jetronic system, since it does not directly measure air flow volume. But by using

various sensors, the calculated air flow volume will have improved accuracy.

◎ Throttle Speed

The air flow volume is measured by throttle position. With this measurement at any given RPM,

the proper fuel amount can be calculated. Since the throttle position determines that amount

of fuel delivery, acceleration response is best with this system. It is very difficult to calculate

air flow accurately in different conditions with this system. That is why it is not commonly

used on vehicle today. (Most use on race vehicles or vehicles with individual throttle bodies)

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２．Air Flow Meter Types

◎ Vane Air Flow Meter (Flap type）

The VAF measure air flow volume by how far the incoming air pushes a plate inside the sensor.

◎ Karman Vortex Air Flow Meter

This Air Flow Meter measures the frequency of vortices (swirls) caused by an obstruction.

◎ Thermal Air Flow Meter（Hot Wire Type）

Inside the Air Flow meter is a heated wire that is kept at a constant temperature. As air

passes through the sensor, it cools this heated wire. The current needed to maintain the

desired temperate is measured to calculate the air flow volume.

Sensor Frequency

Air Flow Volume

Sensor Voltage

Air Flow Volume

Air Flow Volume

Sensor Voltage

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● ECU Control

1. Open Loop Control

ECU controls fuel and ignition systems from input information that is compared to pre-programmed

maps. Receives input from Engine Coolant Temp Sensor, Intake Air Temp Sensor, Throttle

Position Sensor, RPM, Mass Air Flow Sensor, MAP Sensor, Vehicle Speed Sensor, Knock Sensor,

Cam Position Sensor, Crank Position Sensor. 02 Sensor is not monitored while ECU is in Open

Loop Control.

2. Closed Loop Control

Air-fuel mixture will depend mainly on sensor inputs. ECU receives input from same sensors as

Open Loop Control, but with the addition of receiving input from the 02 sensor. The 02 sensor is

used as a feedback signal to control the A/F ratio while in Closed Loop Operation.

Short Term and Long Term fuel trims are the correction coefficients for correcting the amount of

injected fuel. When the A/F ratio is leaner than stoichiometric ratio, the ECM will increase short

term fuel gradually to richen the air fuel mixture. For rich conditions, the short term fuel trim will

be decreased to lean the air fuel mixture. Long term fuel trims are calculated from the short term

fuel trim over a longer period of time.

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● 02 Sensor types

1. Heated O2 Sensor (Volts)

This is generally a narrow band O2 sensor with an output voltage range of 0~1 volt. A condition

that is leaner than stoichiometric would be 0 volts, while a richer condition would result in the O2

sensor sending a 1 volt signal. The change from 0V to 1V occurs approximately at around

stoichiometric ratio.

2. Heated O2 Sensor (mA)

This is generally a wide-band O2 sensor that can detect the oxygen concentration in all ranges, from

lean to rich. The sensor measures oxygen content and sends signal to the ECU as a current value

(mA). Depending on the system, Stoichiometric Ratio may be at 0 mA.

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● Variable Valve Timing Systems

1. VTEC (Variable-Valve Timing and Electronic-Lift Control)

Designed by Honda to have two camshaft profiles (LO-HI) in one camshaft. To activate the more

aggressive camshaft profile, a 12 volt signal (VTS) is sent to the VTEC solenoid to allow oil flow to

the camshaft rocker arms. A pin inside the rocker arms will be forced to slide across the inside of

the rocker arms and lock them together, causing both valves to be opened by a larger and more

aggressive lobe.

On most of the VTEC vehicles, an oil pressure switch is used to monitor the oil pressure in the

VTEC oil delivery passages. The ECU monitors the oil pressure switch(VTM) to make sure the

VTEC solenoid operates properly when the ECU sends it 12v signal. The ECU confirms oil

pressure is present when the VTEC Oil Pressure Switch allows the VTM circuit to be grounded. If

the VTM circuit is grounded other than the time that the ECU sends 12V to the VTEC Solenoid, the

ECU will throw a Check Engine Light.

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2. NVCS (Nissan Valve-Timing Control System)

Designed by Nissan to adjust valve timing. To advance the valve timing, the ECU will activate the

oil control solenoid valve by grounding the solenoid valve circuit. The solenoid will activate to

prevent oil drainage from the camshaft sprocket. By blocking the drainage, it will cause a build in

oil pressure, which will cause the inner part of the sprocket to push out and turn. The effect will

be advanced valve timing and an increase in valve overlap.

NVCS operates as an on-off function and is not a variable valve timing system. Although the

ECU does monitor camshaft timing, it will not throw a check engine light when the NVCS solenoid

valve operates at times other than when the ECU grounds the solenoid valve.

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● ECU Diagrams

1. For the e-manage and e-manage Ultimate systems, you will need to be able to locate specific wires

using diagrams and charts. Depending on the type of ECU and its characteristics, some wires may not

be required to be used. Below is a list of signal wires commonly used for the e-manage and e-manage

Ultimate.

◎ Some vehicles may need to have the 02 sensor wires located as well (for O2 sensor adapter).

Power (+B) ➠ Splice into 12V switched power to the ECU

Ground (E) ➠ Splice into ECU Ground

RPM Signal (I) ➠ Splice into Engine Speed Output from ECU

Throttle (Th) ➠ Splice into Throttle Position Sensor Input

Airflow/Map (Ar) ➠ Cut and Intercept Airflow Meter signal going to ECU

VTEC (VT) ➠ Cut and Intercept signal going from ECU to VTEC solenoid

VTM (VTM) ➠ Cut and Replace Oil Pressure Switch Signal (VTM) with dummy signal from e-manage.

Sensor Ground (#E) ➠ Splice into Injector or Sensor Circuit Ground.

Crank Angle (Ne) ➠ Splice into Crank Angle Sensor Input Signal(※1)

Cam Angle (G) ➠ Splice into Cam Angle Sensor Input Signal(※1)

Intake Temp (A) ➠ Splice into Intake Temp Sensor Input Signal(※1)

Water Temp (W) ➠ Splice into Water Temp Sensor Input Signal(※1)

Knock (Kn) ➠ Splice into Knock Sensor Input Signal(※1)

Pressure Sensor (P) ➠ Cut and Intercept Signal w/ Analog IN/OUT wires(※1) (Cars with airflow + pressure sensor)

Vehicle Speed (SPD) ➠ Cut and Intercept Speed Signal Input(※1)

Injector (#) ➠ Cut and Intercept Injector Signal for +/–mode (※1) or Splice into Injector Signal for + only mode

Igntion (t) ➠ Cut and Intercept Ignition Output Signal

RPM & Ignition (I∙t) ➠ For vehicles that can use the Ignition Signal as an RPM input. (i.e. Honda Distributor)

Ignition (t※∙※) ➠ For Ignition systems that have one channel controlling two cylinders (Waste Spark)

Leading Ign. (tL) ➠ For Rotary Engines: Cut and Intercept Leading Ignition Output Signal

Trailing Ign. (tT) ➠ For Rotary Engines: Cut and Intercept Trailing Ignition Output Signal

Primary Inj. (#P) ➠ For Rotary Engines: Cut and Intercept(※1) or Splice into Primary Injector Output Signal

Secondary Inj. (#S) ➠ For Rotary Engines: Cut and Intercept(※1) or Splice into Secondary Injector Output Signal

02 sensor ➠ Cut and Intercept O2 sensor feedback using O2 Sensor Adapter

Special Notes: (※1) = e-manage Ultimate ONLY.

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2. If the installation manual does not contain the ECU diagram for you vehicle, the wiring can be

figured out by using a factory repair manual. There are some differences in the way manufacturers

design the ECU pin diagrams, but most will have a chart with descriptions and wire color

information for each ECU terminal. Below is a sample diagram of what ECU terminals to look for

and how they will look when made into an e-manage or e-manage ultimate diagram.

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