The fueling calculations used by Emtron are based on an Air Mass per cycle which is then converted to a Fuel Mass based on the requested lambda target. This is true whether the system is using directly measuring airflow from the air mass meter, or calculated air mass from speed density or throttle mass flow (TMF)
The Volumetric Efficiency (VE) table is used when the Air Mass Model is configured for Speed Density.
In Speed Density mode, the ECU does not directly measure the engine airflow. Instead, it calculates the air mass entering each cylinder using the Ideal Gas Law based on:
Engine Displacement
Manifold Absolute Pressure (MAP)
Charge Temperature
Volumetric Efficiency (VE)
The calculated Air Mass per Engine Cycle is then used to determine the required Fuel Mass based on the commanded Lambda Target. The ECU then converts the required fuel mass into an injector pulse width using the configured injector characteristics.
ℹ️ Note
The ECU supports one or two Volumetric Efficiency (VE) tables. The active table configuration is selected using the VE Table Control setting, which determines whether a single VE table is used or whether blending between two VE tables is enabled (Z- Axis).
Volumetric Efficiency (VE) Table
The Volumetric Efficiency (VE) table represents the engine’s ability to fill its cylinders with air under varying engine speeds and loads.
Although referred to as Volumetric Efficiency (VE), the ECU uses VE to determine the air mass trapped within the cylinder. VE is expressed as a percentage and represents the ratio of the actual air mass trapped within the cylinder to the theoretical air mass that would occupy the engine’s swept cylinder volume under standard atmospheric conditions.
The calculated air mass is then used by the ECU to determine the required fuel mass to achieve the commanded Lambda Target.
A higher VE indicates the engine is filling its cylinders more efficiently, requiring more fuel to maintain the commanded Lambda Target.
Most engines typically operate below 100% VE.
ℹ️ Note
The term Volumetric Efficiency is historical and can be misleading. While VE is expressed as a percentage of the cylinder’s theoretical filling, the ECU ultimately uses the VE value to calculate the air mass entering the cylinder. Since fuel delivery is based on air mass rather than air volume, VE is simply a convenient way of modelling the engine’s air pumping efficiency.
Due to intake and exhaust tuning, pressure wave dynamics and scavenging effects, a well-designed naturally aspirated engine can exceed 100% VE over parts of its operating range.
Tuning
Before calibrating the VE table(s), the Lambda Target table(s) should first be configured with the desired lambda or air-fuel ratio for each operating condition.
Once the Lambda Target table(s) have been calibrated, the VE table is adjusted until the measured lambda matches the commanded Lambda Target. The two tables are intrinsically linked, the Lambda Target defines the desired result, while the VE table determines the amount of fuel required to achieve it.
The above VE table example shows the typical range of values.
🔧Tuning Notes
The VE table is calibrated by adjusting its values until the measured lambda matches the commanded Lambda Target across the engine’s operating range.
This process is most efficient when the ECU is configured with a Wideband Lambda input, allowing the measured lambda to be compared directly with the commanded target.
Once the VE table has been correctly calibrated, the engine’s volumetric efficiency model has been established, providing an accurate basis for fuel delivery calculations.
The objective is to minimise the error between the measured lambda and the Lambda Target under all operating conditions.
A simple method of validating the VE calibration is to change the Lambda Target at a specific operating point. If the VE table and injector characterization have been calibrated correctly, the measured lambda should follow the new Lambda Target without requiring further VE adjustments.
If changes to the VE table are required to achieve the new Lambda Target, this may indicate an error in the VE calibration or the configured injector characterization (injector flow, deadtime, or non-linearity).
When Closed Loop Lambda Control is enabled, the VE table provides the feed-forward fuel calculation, while the closed loop controller applies only the corrections necessary to eliminate any remaining fueling error.
VE Table Control
This control determines whether a single target table is used or whether Z-axis blending is enabled between two calibration tables.
Available Options
Value
Mode
0
OFF
1
ON - Table 1
2
ON - Table 2
3
Not Available
4
Not Available
5
Cal Slot
6
ON - Z-Axis
Mode Descriptions
OFF (0)
Disables the Lambda Target table input
ON - Table 1 (1)
Uses VE Table 1 only for air masss speed density model
ON - Table 2 (2)
Uses VE Table 2 only for air masss speed density model
Not Available (3–4)
Reserved for future functionality and should not be selected.
Cal Slot (5)
Enables real-time switching of the Fuel VE tables via calibration slot selection.
This allows the ECU to switch between pre-defined calibration sets without modifying the Table Control setting. See Tuning view -> Cal Control menu
Dual VE tables are particularly useful for engines with significantly different airflow characteristics between operating modes. For example, on a Honda VTEC engine, one VE table can be calibrated for the low-lift cam profile and the second VE table calibrated for the high-lift cam profile. Once both tables have been tuned across the full operating range, the VTEC changeover point can be adjusted to determine the optimum switching RPM without requiring the VE calibration to be retuned.>
Example application:
Table 1 = VTEC Low-lift Cam
Table 1 = VTEC high-lift Cam
The active table can be switched in real time based on RPM or a user defined switch condition
ON - Z-Axis (6)
The Z-Axis enables a user-defined third axis used to swap or blend between VE Table 1 and VE Table 2.
The ECU performs real-time linear interpolation between both VE tables based on the configured Z-Axis input. This allows fuel delivery to be dynamically adjusted across a third operating dimension, which can be spanned using any available runtime parameter within the ECU.
0% Z-axis → 100% Table 1
100% Z-axis → 100% Table 2
Intermediate values → linear interpolation between both tables
VE Blend Table can be enabled under Fuel Table Control :
Tuning -> Fuel -> Fuel Table Control
VE Blend can blend only two VE tables at a time.
Units are 0-100%
0% = First VE Table
100% = Second VE Table
Global Fuel Trim
This function applies a global fuel trim to the base calibration.
It provides a percentage-based adjustment to injector pulse width, allowing the overall air-fuel ratio to be shifted richer or leaner without modifying individual fuel tables.
The trim is applied uniformly across all operating conditions and is independent of engine speed (RPM) and load.
Applied globally to all fuel calculations derived from the base calibration
⚠️ Notes
This function is intended as a calibration and setup aid only.
It allows for a rapid changes to the overall mixture and works independent of RPM and load.
This trim should be returned to 0% before final tuning to ensure the base fuel model is accurate and consistent.
Lambda Target Tables
Overview
The Lambda Target table enables the user to define the desired Lambda target across the operating range of the engine.
The Lambda Target is a primary input to the ECU airflow and fuel model and therefore directly influences the final calculated fuel mass injected into the engine.
Once the Engine VE (Volumetric Efficiency) table is correctly calibrated to achieve the commanded Lambda Target, the engine’s operating Lambda can be adjusted simply by changing the Lambda Target value, without requiring changes to the main fuel calibration.
This target must be defined prior to the calibration of the VE table(s).
For example, if the Main Fuel Table is calibrated such that the engine operates at 1.00 Lambda when the Lambda Target is 1.00, then reducing the Lambda Target to 0.80 will result in the ECU automatically increasing fuel delivery to achieve 0.80 Lambda, without any changes to the Main Fuel Table.
Note: If a change in Lambda Target (e.g. from 1.00 to 0.80) does not result in the measured Lambda matching the target, this indicates an error in the fuel system model, most commonly incorrect injector characterisation which should be corrected before continuing.
Why Lambda is used instead of AFR
Lambda is used as the primary combustion target because it represents the relative air–fuel ratio to stoichiometric, rather than an absolute fuel value.
Since different fuels have different stoichiometric air–fuel ratios, the same AFR value does not represent the same combustion condition across fuels. For example, petrol, ethanol blends, and methanol all require different AFR values to achieve the same combustion state.
Lambda removes this dependency by normalising the mixture to stoichiometric:
Lambda = 1.00 → stoichiometric combustion (regardless of fuel type)
Lambda < 1.00 → rich mixture
Lambda > 1.00 → lean mixture
Because of this, a single Lambda Target can be used across all fuels, while the equivalent AFR target would change depending on fuel composition.
This allows calibration to remain consistent when fuel type changes, while still maintaining the same combustion behaviour.
For this reason, Lambda Targets are preferred over AFR Targets in the ECU fuel model, as they provide a universal reference independent of fuel stoichiometry.
Lambda Target Tables
Two Lambda Target tables are available within the ECU. Either table can be used to define the engine’s Lambda target across the operating range.
The active table is selected using the Lambda Target Table Control setting.
Only the selected (active) table is used by the ECU for fuel model calculations and closed-loop control. The inactive table has no effect on engine operation until it is selected as the active source.
Normally Lambda Target Table 1 is used.
Should an actual Air Fuel Ratio be required to be displayed, this can be achieved by right mouse click on table and selecting AFR Unit . Once activated, if the fuel model is set to a single fuel type, the Lambda Table 1 will be displayed in regular AFR units.
⚠️ Warning:
This feature will not work with flex or dual fuel models - see Stoich Ratio Setup
Example 1: Gasoline fuel AFR shown
Example 2: Methanol fuel AFR shown
Lambda Target Offset Table
The Lambda Target Offset is applied as an absolute correction to the base Lambda Target defined in the Lambda Target table.
For example, if the Lambda Target table value is 1.000 and a Lambda Target Offset of -0.150 Lambda is applied, the resulting effective Lambda Target becomes:
1.000 + (-0.150) = 0.850
This offset is absolute (not percentage-based) and directly adds or subtracts from the base Lambda Target value.
It allows the final Lambda Target to be adjusted dynamically without modifying the base calibration table.
This control determines whether a single target table is used or whether Z-axis blending is enabled between two calibration tables.
Available Options
Value
Mode
0
OFF
1
ON - Table 1
2
ON - Table 2
3
Not Available
4
Not Available
5
Cal Slot
6
ON - Z-Axis
Mode Descriptions
OFF (0)
Disables the Lambda Target table input
ON - Table 1 (1)
Uses Table 1 only for Lambda Target calculation.
Typically represents the base calibration (e.g. Petrol Lambda Target strategy).
ON - Table 2 (2)
Uses Table 2 only for Lambda Target calculation.
Typically represents an alternative calibration strategy (e.g. Methanol or high-load enrichment strategy).
Not Available (3–4)
Reserved for future functionality and should not be selected.
Cal Slot (5)
Enables real-time switching of the active Lambda Target table via calibration slot selection.
This allows the ECU to switch between pre-defined calibration sets without modifying the Table Control setting. See Tuning view -> Cal Control menu
Example application:
Table 1 = Petrol Lambda Target calibration
Table 2 = Methanol Lambda Target calibration
The active table can be switched in real time depending on:
Fuel type
Engine mode
Test or development configuration
This mode is commonly used for:
Rapid calibration comparison
Track-side strategy changes
Different Fuel system
ON - Z-Axis (6)
Enables Z-axis blending between Table 1 and Table 2.
The ECU interpolates between both tables based on the configured Z-axis input (typically Ethanol Content %), producing a blended fuel value.
0% Z-axis → 100% Table 1
100% Z-axis → 100% Table 2
Intermediate values → linear interpolation between both tables
Z-Axis Blended (Dual Table Interpolation)
The ECU supports a Z-axis blending strategy that allows lambda targets to be interpolated between two tables based on a third operating axis.
Concept Overview
Two base Lambda Target tables are defined:
Table 1 (Reference Fuel – Petrol) Defines Lambda Targets for standard petrol operation.
Table 2 (Alternative Fuel – High Oxygen Content Fuel) Defines Lambda Targets for high ethanol or methanol operation.
A Z-axis input (typically fuel composition such as ethanol content) is used to interpolate between the two tables.
This example shows the blend between Table 1 and Table 1 spanned on the Z-axis using Ethanol content
Injection Timing
⚙️ Injection Timing Table
The Injection Timing table defines the desired injection event angle as a function of engine operating conditions.
Table values are expressed in crankshaft degrees Before Top Dead Centre (BTDC) and are referenced to Cylinder 1 Compression TDC (i.e 400 = 400 degrees before TDC Cylinder 1 compression). The table is configured as an advance-style table, therefore larger values schedule the injection event earlier in the engine cycle.
The interpretation of the table values depends on the selected Injection Timing Reference mode:
Start of Injection – Table values define when the injector begins delivering fuel. End of Injection – Table values define when the injector finishes delivering fuel.
Table Size: 22 columns x 12 rows
Resolution: 0.1 Deg Range: 0.0 - 720.0 Degs
⚠️ Notes
When Staged Injection is enabled, a secondary Injection Timng Table can be used which operates independently of the Primary Injectors. The Sec Injectors can be advanced up during the initial transition into staged mode to help improve the overall smoothness during this event
⚙️ Injection Timing Reference
The Injection Timing Reference setting determines whether the Injection Timing table values specify the Start of Injection (SOI) or End of Injection (EOI) event.
Injection Timing determines when fuel is delivered into the engine cycle relative to Cylinder 1 Compression Top Dead Centre (TDC).
Injection Timing values are expressed in crankshaft degrees Before Top Dead Centre (BTDC) . Larger values schedule the injection event earlier in the engine cycle.
Timing Reference Examples
Value
Description
400° BTDC
400° before Cylinder 1 Compression TDC
360° BTDC
TDC between the exhaust and intake strokes (valve overlap period)
300° BTDC
Approximately 60° after intake valve opening on a typical 4-stroke engine
Options
Value
Mode
0
Start of Injection
1
End of Injection
Start of Injection (SOI)
The Injection Timing table value defines when the injector begins delivering fuel.
The ECU calculates the corresponding End of Injection based on the injector pulse width and operating conditions.
This mode is typically used when the desired fuel delivery strategy is based on the opening point of the injection event.
End of Injection (EOI)
The Injection Timing table value defines when the injector finishes delivering fuel.
The ECU automatically calculates the corresponding Start of Injection based on the injector pulse width and operating conditions.
This mode is commonly used when precise control of fuel delivery relative to intake valve events is required.
For sequential injection systems, End of Injection mode is often preferred because the completion of fuel delivery can be aligned with intake valve events. This can reduce fuel wall wetting, improve fuel preparation and promote more consistent cylinder-to-cylinder fuel distribution.
⚠️ Notes
Injection timing values are referenced to Cylinder 1 Compression TDC regardless of the cylinder being fuelled.
Higher values move the injection event earlier in the engine cycle.
Whether the value represents the Start or End of Injection depends on the selected Injection Timing Reference mode.
The actual injector opening and closing points will vary with pulse width, engine speed and operating conditions.
Example for Staged Injection with the angle spanned across intake camshaft target angle & fuel mass final (g/cyl).
Starting Fuel Setup
Starting Fuel Overview
Engine starting fuel requirements differ significantly from those required during normal engine operation. At low engine speeds and temperatures, a portion of the injected fuel does not immediately contribute to combustion as it can condense on intake surfaces, intake valves and cylinder walls. Additional fuel compensation is therefore required to ensure sufficient combustible fuel reaches the cylinder during the starting process.
The starting fuel strategy consists of three distinct phases:
Phase 1 – Pre-Crank Fuel
Pre-crank fuel is delivered before or at the beginning of engine cranking. The purpose of this fuel is to establish an initial fuel film on the intake port and valve surfaces, reducing the amount of fuel lost to wall wetting during the first combustion events.
Correctly calibrated pre-crank fuel can improve start quality, reduce cranking time and promote faster engine burst.
Phase 2 – Cranking Fuel
During cranking additional fuel enrichment is required to compensate for fuel condensation and poor fuel vaporisation, particularly at lower engine and ambient temperatures.
Cranking fuel provides the additional fuel necessary to achieve a combustible air-fuel mixture while the engine is rotating below its self-sustaining speed. Fuel requirements during this phase are highly dependent on coolant temperature, fuel characteristics, engine design and injector placement.
Phase 3 – Post-Start Fuel
Once the engine has fired and transitioned from cranking to running, additional fuel compensation is typically required for a short period. The Fuel films established during the starting process continues to evolve and combustion stability may not yet be fully established.
Post-start fuel provides a temporary enrichment immediately after engine burst and gradually decays over time. This ensures a smooth transition from starting operation to normal fuel calculations while maintaining stable combustion and drivability. As the post-start compensation decays to zero, fueling returns entirely to the standard operating fuel model with no additional start-related compensation applied.
⚙️ Pre-Crank Fuel Enable
Enables and configures a pre-crank fuel injection event. This feature can improve engine start-up by providing an initial fuel charge before or during cranking, helping the engine fire more quickly.
Options
Value
Mode
0
Off
1
Start Position
2
First Crank Index Signal (Single Event)
3
Key On
4
First Crank Index Signal (Multiple Events)
Mode Descriptions
Off
Disables all pre-crank injection events.
Start Position
Triggers a pre-crank injection event when the configured Start Position Switch becomes active. The Start Position Switch must be configured for this mode to operate.
First Crank Index Signal (Single Event)
Triggers a single pre-crank injection event when the first crank index signal is detected after ECU power-up.
Key On
Triggers a single pre-crank injection event when the ignition is switched to the ON position after ECU power-up.
First Crank Index Signal (Multiple Events)
Triggers the pre-crank injection event on the first crank index signal detected during engine cranking. Unlike the other modes, this mode automatically re-arms after the engine has stopped, allowing the pre-crank injection event to occur again on subsequent start attempts without requiring an ECU power cycle. To prevent repeated pre-crank injection events during unsuccessful starts or engine stalls, a lockout mechanism is applied. Before another pre-crank event can occur, the engine re-arming conditions must be met:
Exceed 400 RPM. Remain above 400 RPM for at least 1 second.
Once these conditions have been satisfied and engine speed subsequently returns to 0 RPM, the pre-crank injection event will be re-enabled and available for the next engine start.
⚠️ Notes
Modes 1, 2 and 3 perform only a single pre-crank injection event after ECU power-up. The ECU power must be cycled before another pre-crank injection event can occur using the Modes.
Mode 4 the pre-crank event can be re-triggered automatically once the re-arming conditions have been met.
⚙️ Pre-Crank Pulse Count
Sets the number of fuel injection pulses during the pre-crank priming event. Using multiple shorter pulses helps improve fuel atomisation and distribution while reducing the risk of liquid fuel accumulation.
Increasing the pulse count can be beneficial when using fuels that require significantly more fuel for cold starting, such as ethanol-based fuels. Rather than using a single large injection pulse, the required fuel can be distributed across multiple smaller pulses.
This approach can improve fuel atomisation and reduce the likelihood of fuel pooling or entering the cylinder in a liquid state, which can lead to spark plug wetting and poor starting performance.
Typical Applications:
Ethanol and high-ethanol-content fuels.
Engines requiring large amounts of pre-crank fuel.
Situations where a single large pulse results in poor start quality.
⚙️ Pre-Crank Pulse Interval
Sets the time delay between consecutive pre-crank injection pulses. This parameter only applies when Pre-Crank Pulse Count is greater than 1.
It controls the spacing between each injection pulse during the pre-crank event, allowing adjustment of fuel delivery timing and mixture preparation.
Short interval: higher fuel density, increased wetting risk.
Long interval: improved atomisation, reduced total delivery rate.
The interval should be long enough to allow fuel from each pulse to disperse and form a stable fuel film before the next pulse is delivered. Excessively short intervals may reduce the benefit of using multiple pulses, while excessively long intervals can unnecessarily delay the start sequence.
🔧 Tuning Guidelines
When additional pre-crank fuel is required, it is generally preferable to increase the Pre-Crank Pulse Count rather than significantly increasing the fuel delivered in a single pulse.
A good starting point is:
Set Pre-Crank Multi Pulse Interval to approximately 10 ms.
Increase Pre-Crank Pulse Count by one pulse at a time.
Evaluate cold start performance after each adjustment.
Continue increasing the pulse count until no further improvement in start quality is observed.
Typical applications require between 1 and 6 pulses, with higher pulse counts generally only required for ethanol-based fuels or engines requiring large amounts of pre-crank fuel.
Pre-crank fuel is used to establish an initial fuel film on the intake port and valve surfaces before the engine begins cranking. This helps compensate for fuel that would otherwise be lost to wall wetting during the first combustion events, improving engine start quality and reducing cranking time.
Pre-crank fuel is calibrated using a three-dimensional Pre-Crank Fuel Table. The table allows the amount of fuel delivered during each pre-crank injection event to be varied over two configurable operating axes, providing flexibility for different engine and fuel combinations.
In most applications, the table is configured as a function of Engine Coolant Temperature only (effectively operating as a 2D table), with colder engine temperatures requiring greater pre-crank fuel.
The fuel quantity defined in this table is applied whenever a pre-crank injection event is triggered via the Pre-Crank Injection Mode setting .
🔧 Tuning Guidelines
Increase fuel values if the engine requires excessive cranking before firing.
Increase fuel values if the engine struggles to fire during cold starts.
Decrease fuel values if the engine exhibits signs of flooding, spark plug wetting, or excessively rich starts.
Ethanol-based fuels typically require significantly more pre-crank fuel than gasoline-based fuels.
Large increases in fuel quantity are often better achieved using multiple pulses rather than a single large pulse. Refer to Pre-Crank Pulse Count and Pre-Crank Multi-Pulse Interval for additional tuning options.
⚠️ Important Notes
Excessive pre-crank fuel can result in spark plug wetting and poor start quality.
The optimum fuel quantity will vary depending on fuel type, injector location, engine design, and ambient temperature.
Pre-crank fuel should be used to improve initial combustion quality, not to compensate for incorrectly calibrated cranking fuel.
During cranking, engine speed is low and fuel atomisation is poor. Additional fuel is required to compensate for fuel condensation on intake and cylinder surfaces and to ensure a combustible air-fuel mixture.
Cranking fuel is calibrated using one or two three-dimensional Cranking Fuel Tables. Each table allows the amount of fuel delivered during the cranking injection event to be varied over two configurable operating axes, providing precise control over cranking fuel under different starting conditions.
The cranking threshold is defined when the engine speed is below the configured Crank Exit RPM setting.
The Crank Fuel Table is typically configured as a function of coolant temperature and firing events ; the colder engine temperatures requiring greater fuel enrichment.
Fuel from this table is applied continuously while the engine remains in the cranking state.
🔧 Tuning Guidelines
Increase fuel values if the engine struggles to fire or requires excessive cranking time.
Decrease fuel values if the engine exhibits signs of flooding.
Cold temperature regions generally require significantly more fuel than warm temperature regions.
Post-Start Fuel Table
The Post-Start Fuel Table provides temporary fuel enrichment immediately after the engine transitions from cranking to running.
When engine speed exceeds the configured Crank Exit RPM, the ECU exits the cranking state and begins applying the Post-Start Fuel Table. This additional fuel helps stabilise combustion during the first few seconds of engine operation while fuel films and air-fuel mixture conditions settle.
The Post-Start Fuel Table is typically configured as a function of coolant temperature, with colder engine temperatures requiring greater enrichment.
Post-start fuel compensation gradually decays to zero over a user-configurable period, allowing a smooth transition to normal fuel calculations.
🔧 Tuning Guidelines
Increase fuel values if the engine starts successfully but immediately stumbles, misfires, or stalls.
Decrease fuel values if the engine starts cleanly but runs excessively rich following start-up.
Ensure the post-start decay period is long enough to maintain stable combustion, particularly during cold starts.
ℹ️ Crank Exit RPM
The Crank Exit RPM setting defines the engine speed at which the ECU transitions from the Crank Fuel Table to the Post-Start Fuel Table.
Once engine speed exceeds the configured Crank Exit RPM, the engine is considered to be running and post-start fueling becomes active.
Note: Crank Exit RPM is a global ECU setting and may also be used by other ECU functions to determine whether the engine is in a cranking or running state.
Each starting fuel phase (Pre-Crank Fuel, Cranking Fuel, and Post-Start Fuel) includes a Table Control parameter which defines how the ECU sources fuel values during engine start.
This control determines whether a single fuel table is used or whether Z-axis blending is enabled between two calibration tables.
Available Options
Value
Mode
0
OFF
1
ON - Table 1
2
ON - Table 2
3
Not Available
4
Not Available
5
Not Available
6
ON - Z-Axis
Mode Descriptions
OFF (0)
Disables the selected starting fuel phase. No fuel contribution is applied from this table.
ON - Table 1 (1)
Uses Table 1 only for fuel calculation.
Typically represents the base calibration (e.g. Petrol / 0% Ethanol reference).
ON - Table 2 (2)
Uses Table 2 only for fuel calculation.
Typically represents the alternative calibration (e.g. E100 / 100% Ethanol reference).
ON - Z-Axis (6)
Enables Z-axis blending between Table 1 and Table 2.
The ECU interpolates between both tables based on the configured Z-axis input (typically Ethanol Content %), producing a blended fuel value.
0% Z-axis → 100% Table 1
100% Z-axis → 100% Table 2
Intermediate values → linear interpolation between both tables
Not Available (3–5)
Reserved for future functionality and should not be selected.
Z-Axis Blended Fueling (Dual Table Interpolation)
The ECU supports a Z-axis blending strategy that allows fuel values to be interpolated between two tables based on a third operating axis, typically Ethanol Content (E-content).
This feature is used to account for differences in fuel properties, vaporisation characteristics and cold start behaviour between fuels like Petrol (Gasoline) and Ethanol (E100).
Concept Overview
Two base tables are defined:
Table 1 (0% Ethanol Reference) Represents fuel requirements for standard Petrol operation.
Table 2 (100% Ethanol Reference) Represents fuel requirements for full Ethanol (E100) operation.
A third axis (Z-axis), typically Ethanol Content (0–100%), is used to interpolate between these two tables.
Operation
For any given operating condition, the ECU:
Looks up the required value in Table 1
Looks up the required value in Table 2
Reads the current Z-axis value (e.g. Ethanol Content %)
Calculates a blended output using linear interpolation between the two tables
Example
At 0% Ethanol, the output is taken entirely from Table 1 (Petrol)
At 100% Ethanol, the output is taken entirely from Table 2 (Ethanol)
At 50% Ethanol, the output is a 50/50 blend of both tables
At intermediate values, the ECU smoothly interpolates between the two
Application to Starting Fuel
This blending method can be applied to multiple starting fuel phases:
Pre-Crank Fuel
Cranking Fuel
Post-Start Enrichment
Each phase is independently blended using the same Z-axis strategy, allowing the ECU to automatically adjust fuel delivery based on ethanol content.
Benefits
Eliminates the need for separate fuel maps per fuel type
Ensures smooth transitions between fuel blends
Maintains consistent start behaviour across ethanol ratios
Improves cold-start robustness for flex-fuel operation
PreCrank Z-Axis Setup
The Z-Axis activates a user definable X-Axis to swap or blend between PreCrank tables based on the selected runtime
PreCrank ZAxis spanned across ethanol content example shown above
Crank Z-Axis Setup
The Z-Axis activates a user definable X-Axis to swap or blend between Crank tables based on the selected runtime
Crank ZAxis spanned across ethanol content example shown above
Post Start Z-Axis Setup
The Z-Axis activates a user definable X-Axis to swap or blend between Post Start tables based on the selected runtime
Post Start ZAxis spanned across ethanol content example shown above
Engine Temperature Fuel Table
Overview
Additional fuel is typically required when the engine is cold to compensate for reduced fuel vaporisation and increased fuel condensation on intake port surfaces, intake valves and cylinder walls.
At low engine temperatures, a portion of the injected fuel does not immediately contribute to combustion. Instead, fuel can form liquid films on engine surfaces, reducing the amount of combustible fuel available within the cylinder. To maintain the desired air-fuel ratio and ensure stable engine operation, additional fuel compensation is required.
As engine temperature increases, fuel vaporisation improves and wall-wetting effects are reduced. The amount of compensation required therefore decreases progressively as the engine approaches normal operating temperature.
Engine load and airflow also influence the amount of compensation required. At higher engine loads, increased air mass flow and air velocity improve fuel atomisation and vaporisation, reducing the amount of fuel lost to wall wetting. As a result, less temperature-based enrichment is typically required at higher loads than at idle or light load conditions for the same engine temperature.
The Engine Temperature Fueling table is used to define this compensation as a function of engine coolant temperature and load (engine air mass flow). Larger corrections are required at low temperatures, gradually reducing to zero additional compensation once normal operating temperature has been reached.
Correct calibration of Engine Temperature Fueling is important for cold start performance, idle stability, throttle response and overall drivability during engine warm-up.
Engine Temperature Warm-up Z-axis Setup
The Z-Axis activates a user definable X-Axis to swap or blend between Engine Temperature Tables 1 and 2 based on the selected runtime. Refer to the supplied sample showing Engine Temperature ZAxis spanned across ethanol content.
Fuel Tuning Overview
Overview
The fueling calculations used by Emtron are based on an Air Mass per cycle which is then converted to a Fuel Mass based on the requested lambda target. This is true whether the system is using directly measuring airflow from the air mass meter, or calculated air mass from speed density or throttle mass flow (TMF)
Example.
With an engine operating at 85% VE and has a known Charge Temperature and Manifold Pressure, the ECUs calculates an Air Mass per Induction of 0.789 grams. To achieve at Lambda target of 0.85 (12.50 AFR petrol) the corresponding fuel mass needs to be 0.06312 grams. With a known Injector Size in cc/min and Fuel Density (g/ml) the injector mass flow can be determined. Lets use 10.73 grams/sec.
ℹ️ Note Other factors also affect the injector mass flow. When enabled the ECU monitors the differential pressure across the injector and corrects if it moves away from the nominal static pressure. It does this using “Bernoulli’s equation” which is a square root law.
Knowing that our fuel injector has a static flow rate of 10.73 grams per second, we divide that into our fuel mass and arrive at a injector pulsewidth value of 5.704 ms. However, the injector cannot just be opened for this time to achieve the calculated Fuel Mass. The Dynamic Characteristics of the fuel injector must be used. This includes injector deadtime and low pulse width non-linearities.
The Graph below of Theoretical vs Actual flow explains this better. The Blue line is the Raw/Theoretical Flow and the Red line is the actual Injector Flow .. note the large error. At 5.7ms the actual fuel mass produced by the injector is 0.0587g instead of the calculated 0.06312 g. This is only 93% of the fuel requested.
The flow error is caused by an offset that exists between the actual injector flow (Red line) and the theoretical flow (Blue line). This offset exists on all injectors and must be included for the fuel calculation to be accurate. As the offset is constant across the “majority” of the injector operating range, we can correct for it by adding it to our final injector pulsewidth. This offset error/flow error is known as Injector Deadtime. The ECUs uses a 3D deadtime table spanned on Battery Voltage and Differential Fuel Pressure. See section Injector Deadtime Table for more information.
Once the offset is corrected the Theoretical vs Actual flow graph looks like:
The correction across “most” of the operating range is complete and we can expect the ECU calculated pulsewidth to deliver the requested mass flow. However the range at low pulsewidth still has errors i.e there is a difference between the theoretical and actual pulse with. This is known as the “non linear operating range” of the injector and the graph below has this area zoomed in.
Below 2 ms we have a situation similar to our initial conditions where there was an offset between the actual flow, and theoretical flow of the injector. Unlike the offset within the linear operating range of the injector, this is not constant, and cannot be corrected for with a single value.
The solution is the low pulse adder table which uses offset values that vary with pulsewidth, correcting the lower non linear operating range of the injector. More information can be found Injector Low Pulsewidth Linearisation
With the addition of these values the ECU can achieve nearly perfect fueling down to practically zero flow, and the ECU can do its job of calculating and commanding the correct air fuel ratio under all operating conditions.
Charge Temperature Estimation
Charge Temperature Estimate Table - Overview
The Charge Temperature Estimate table is used to calculate the estimated temperature of the air entering the combustion chamber. This estimated charge temperature is derived by blending the Inlet Air Temperature (IAT) sensor reading with the Engine Coolant Temperature (ECT).
Under many operating conditions, the measured intake air temperature does not accurately represent the temperature of the air charge entering the cylinder. Heat transfer from the intake manifold, cylinder head and engine components can significantly warm the intake charge, particularly during idle, low airflow and hot restart conditions.
The Charge Temperature Estimate table allows the ECU to compensate for these effects by blending the Intake Air Temperature with the Engine Coolant Temperature as a function of engine operating conditions.
Table Values
Table values are expressed as a percentage and determine the contribution of the Engine Coolant Temperature to the calculated charge temperature.
Value
Estimated Charge Temperature
0%
Charge Temperature = Intake Air Temperature
50%
Charge Temperature = Midway between Intake Air Temperature and Engine Coolant Temperature
100%
Charge Temperature = Engine Coolant Temperature
ℹ️ Important
The Charge Temperature Estimate function uses only the configured Inlet Air Temperature (IAT) sensor and Engine Coolant Temperature (ECT) sensor to estimate the Charge Temperature.
No other air temperature source is considered during this calculation. If multiple temperature sensors are configured within the ECU, only the Inlet Air Temperature (IAT) sensor is used for the air temperature component of the blend.
🔧 Tuning Guidelines
At low engine speed and light engine load, airflow through the intake system is relatively low. This allows heat from the engine to warm the intake manifold and incoming air, causing the actual charge temperature to be significantly higher than the measured Intake Air Temperature. Higher blend values are therefore typically required.
As engine speed and engine load increase, air mass flow through the intake system also increases. The higher airflow reduces heat transfer from the engine, allowing the Intake Air Temperature sensor to more accurately represent the temperature of the air entering the cylinder. Consequently, lower blend values are generally required.
For turbocharged and supercharged engines operating under boost, the Intake Air Temperature sensor typically provides an accurate measurement of the compressed intake charge. Little or no Engine Coolant Temperature blending is therefore normally required at higher engine loads.
ℹ️ Notes
The table axes are Engine Speed (RPM) and Efficiency Calculation/ Manifold Pressure (kPa).
Lower table values place greater reliance on the Intake Air Temperature sensor.
Higher table values increase the influence of Engine Coolant Temperature to compensate for engine heat soak.
Correct calibration improves air density estimation, resulting in more accurate fuel delivery and ignition calculations during idle, heat soak, hot restart and transient operating conditions.
Charge Temperature Offset Table
The Charge Temperature Offset table applies an absolute temperature correction to the calculated Charge Temperature Estimate. This table is used to compensate for the cooling effect of fuel evaporation, which is not directly accounted for by the Charge Temperature Estimate calculation.
Table values are expressed in degrees Celsius (°C) and are added to or subtracted from the calculated Charge Temperature Estimate. A negative value reduces the calculated Charge Temperature, while a positive value increases it.
Typical Table Axes
X-Axis: Stoichiometric Target (AFR)
Y-Axis: Inlet Air Temperature (IAT)
Operation
Different fuels absorb different amounts of heat as they evaporate. Fuels with a high latent heat of vaporisation, such as Ethanol and Methanol, can significantly cool the intake charge during the injection process. By applying a negative Charge Temperature Offset, the ECU can compensate for this evaporative cooling effect, producing a more accurate estimate of the air charge temperature for fuel and ignition calculations.
For conventional gasoline fuels, little or no offset is typically required.
🔧 Tuning Guidelines
Gasoline applications typically require minimal or no correction.
Ethanol blends generally require a moderate negative offset.
Methanol applications often require a larger negative offset due to its high evaporative cooling effect.
Flex Fuel applications can use this table to progressively increase the cooling correction as ethanol content increases. Refer to the supplied sample calibration for an example implementation.
ℹ️ Important
The Charge Temperature Offset is applied after the Charge Temperature Estimate has been calculated. It does not alter the Charge Temperature Estimate blending between the Inlet Air Temperature (IAT) and Engine Coolant Temperature (ECT); it simply adds or subtracts a fixed temperature offset from the final calculated Charge Temperature Estimate.
Charge Temperature Fuel Table
The Charge Temperature Fuel table applies a percentage fuel correction to the Base Pulse Width
The ECU uses the Charge Temperature Estimate during the air mass calculation to determine the amount of air entering the engine. The calculated air mass is then used to determine the required fuel delivery.
In some engine combinations, the calculated charge temperature may not perfectly model the actual cylinder charge temperature under all operating conditions. This can result in small fueling errors. The Charge Temperature Fuel table provides a means of applying a fine fuel correction to compensate for these residual errors.
Table Values
Table values are expressed as a percentage (%).
Positive values increase the Base Pulse Width (richer).
Negative values decrease the Base Pulse Width (leaner).
0% applies no fuel correction.
🔧Tuning Notes
In most applications, this table can be left at 0% across the entire operating range.
The Charge Temperature Estimate table should be calibrated first to provide the most accurate estimate of the cylinder charge temperature. Then adjust the Charge Temperate Fuel Table if required.
Large corrections typically indicate that the Charge Temperature Estimate table should be reviewed before using this table for compensation.
ℹ️ Important
This table does not modify the calculated Charge Temperature. It applies a percentage correction to the Base Pulse Width after the Charge Temperature Estimate has been used during the ECU’s air mass calculation.
Charge Temperature Fuel Table Control
Enables or disables the Charge Temperature Fuel Table.
When enabled, the Charge Temperature Estimate Fuel Table applies a percentage fuel correction to the Base Pulse Width.
When disabled, no fuel correction is applied and the Charge Temperature Fuel Table is ignored.
Options
Value
Mode
0
Disabled
1
Enabled
⚠️ Notes
In most applications, the Charge Temperature Fuel Table can remain disabled, as little or no additional fuel correction is typically required.
Acceleration Fuel Compensation
During rapid changes in throttle position and engine load, fuel delivery does not immediately track the change in airflow. This is due to a portion of the injected fuel temporarily adhering to the intake port walls and intake valves as a liquid film before it evaporates and is drawn into the combustion chamber.
When airflow increases rapidly, additional fuel is temporarily required to establish the larger fuel film while maintaining the correct air-fuel ratio. Without this compensation, the engine will momentarily operate lean, resulting in hesitation, poor throttle response or engine stumble.
Conversely, when airflow decreases rapidly, the existing fuel film continues to evaporate even though less fuel is being injected. This can temporarily enrich the mixture, requiring fuel to be removed to maintain the commanded air-fuel ratio.
Transient Fuel Compensation automatically adds or subtracts fuel during rapid changes in engine airflow to maintain the commanded air-fuel ratio, improve throttle response and ensure smooth engine drivability. During operation, the ECU continuously calculates the following transient fuel runtimes. These values are applied to the Final Injection Pulse Width to compensate for transient fuel film dynamics.
Runtime
Description
Accel Fuel
Additional injector pulse width calculated during acceleration and added to the Final Injection Pulse Width.
Accel Clamp
Maximum transient fuel that may be added under the current operating conditions.
Decel Fuel
Injector pulse width removed during deceleration and subtracted from the Final Injection Pulse Width.
Decel Clamp
Maximum transient fuel that may be removed under the current operating conditions.
Fuel Accel/Decel Scaler
Engine Temperature compensation multiplier applied to the calculated Accel Fuel and Decel Fuel corrections.
Transient Setup
Accel Enable Enables or disables Transient Acceleration Fuel Compensation.
Decel Enable Enables or disables Transient Deceleration Fuel Compensation.
Accel/Decel Mode Selects the runtime input used to initiate the transient fuel compensation function.
Value
Input
0
TPS 1 – Throttle Position Sensor 1 or Drive-By-Wire Servo Position Sensor 1(when enabled)
1
MAP – Manifold Absolute Pressure
2
PP 1 – Pedal Position Sensor 1
Accel/Decel Threshold (+/-) Defines the minimum rate of change required to activate the transient fuel compensation function. The threshold is expressed as the rate of change per second.
Lower values increase sensitivity, causing the function to activate more readily.
Higher values reduce sensitivity and help prevent unnecessary transient fuel corrections.
A typical starting value is 1.0 units/second of the selected input.
A typical value is 1.0 %/sec.
Accel Sensitivity Table
The Accel Sensitivity Table is the multiplication factor, expressed as a percentage, that determines the amount of transient fuel added based on the rate of change of the selected Accel/Decel Mode.
Example:
Operating Conditions
TPS Rate of Change (dTPS1) = 20 %/sec
Accel Sensitivity = 10%
Base Pulse Width = 5.0 ms
Calculation
Accel Fuel = dTPS1 × Accel Sensitivity
= 20 × 0.10
= 2.0 ms
Final Injection Pulse Width
= Base Pulse Width + Accel Fuel
= 5.0 ms + 2.0 ms
= 7.0 ms
Accel Clamp Table
The Accel Clamp Table limits the maximum amount of additional fuel that can be applied during transient acceleration enrichment events. It defines the maximum allowable increase in injector pulse width (PW), expressed as a percentage of the calculated base fuel pulse width. This prevents excessive transient enrichment during rapid throttle changes, helping to maintain stable air-fuel ratio control and avoiding over-fuelling.
Example:
Calculation
Accel Clamp = 50%
Base Fuel Pulse Width = 4.0 ms
Maximum additional fuel allowed:
= 50% of 4.0 ms
= 0.5 × 4.0 ms
= 2.0 ms
Therefore:
- Base PW = 4.0 ms
- Max Accel Enrichment = 2.0 ms
- Total Maximum PW = 6.0 ms
Accel Engine Temperature Comp Table
The Accel Engine Temperature Compensation Table introduces a multiplier of the calculated accel fuel value against engine temperature
Example:
Calculation
Accel fuel = 10ms
Engine Temperature Comp = 1.5
Total Accel fuel = 10 * 1.5 = 15.0ms
Accel Decay Table
The Accel Decay Table defines the rate at which transient acceleration fuel is removed from the fueling calculation. This value determines how quickly the additional enrichment decays over successive engine cycles, expressed as a percentage reduction per cycle.
Example:
Calculation
Accel decay = 10%
Accel fuel will decay back 10% every cycle
Deceleration Fuel Compensation
During rapid changes in throttle position and engine load, fuel delivery does not immediately track the change in airflow. This is due to a portion of the injected fuel temporarily adhering to the intake port walls and intake valves as a liquid film before it evaporates and is drawn into the combustion chamber.
When airflow increases rapidly, additional fuel is temporarily required to establish the larger fuel film while maintaining the correct air-fuel ratio. Without this compensation, the engine will momentarily operate lean, resulting in hesitation, poor throttle response or engine stumble.
Conversely, when airflow decreases rapidly, the existing fuel film continues to evaporate even though less fuel is being injected. This can temporarily enrich the mixture, requiring fuel to be removed to maintain the commanded air-fuel ratio.
Transient Fuel Compensation automatically adds or subtracts fuel during rapid changes in engine airflow to maintain the commanded air-fuel ratio, improve throttle response and ensure smooth engine drivability. During operation, the ECU continuously calculates the following transient fuel runtimes. These values are applied to the Final Injection Pulse Width to compensate for transient fuel film dynamics.
Runtime
Description
Accel Fuel
Additional injector pulse width calculated during acceleration and added to the Final Injection Pulse Width.
Accel Clamp
Maximum transient fuel that may be added under the current operating conditions.
Decel Fuel
Injector pulse width removed during deceleration and subtracted from the Final Injection Pulse Width.
Decel Clamp
Maximum transient fuel that may be removed under the current operating conditions.
Fuel Accel/Decel Scaler
Engine Temperature compensation multiplier applied to the calculated Accel Fuel and Decel Fuel corrections.
Transient Setup
Accel Enable Enables or disables Transient Acceleration Fuel Compensation.
Decel Enable Enables or disables Transient Deceleration Fuel Compensation.
Accel/Decel Mode Selects the runtime input used to initiate the transient fuel compensation function.
Value
Input
0
TPS 1 – Throttle Position Sensor 1 or Drive-By-Wire Servo Position Sensor 1(when enabled)
1
MAP – Manifold Absolute Pressure
2
PP 1 – Pedal Position Sensor 1
Accel/Decel Threshold (+/-) Defines the minimum rate of change required to activate the transient fuel compensation function. The threshold is expressed as the rate of change per second.
Lower values increase sensitivity, causing the function to activate more readily.
Higher values reduce sensitivity and help prevent unnecessary transient fuel corrections.
A typical starting value is 1.0 units/second of the selected input.
A typical value is 1.0 %/sec.
Decel Sensitivity Table
The Decel Sensitivity Table is the multiplication factor, expressed as a percentage, that determines the amount of transient fuel removed based on the rate of change of the selected Accel/Decel Mode.
Example:
Operating Conditions
TPS Rate of Change (dTPS1) = 10 %/sec
Decel Sensitivity = 10%
Base Pulse Width = 5.0 ms
Calculation
Decel Fuel = dTPS1 × Accel Sensitivity
= 10 × 0.10
= 1.0 ms
Final Injection Pulse Width
= Base Pulse Width - Accel Fuel
= 5.0 ms - 1.0 ms
= 4.0 ms
Decel Clamp Table
The decel Clamp Table limits the maximum amount of fuel that can be remvoved during transient deceleration event. It defines the maximum allowable decrease in injector pulse width (PW), expressed as a percentage of the calculated base fuel pulse width. This prevents excessive transient enleanment during rapid throttle changes, helping to maintain stable air-fuel ratio control and avoiding under-fuelling.
Example:
Calculation
Accel Clamp = 50%
Base Fuel Pulse Width = 4.0 ms
Maximum additional fuel allowed:
= 50% of 4.0 ms
= 0.5 × 4.0 ms
= 2.0 ms
Therefore:
- Base PW = 4.0 ms
- Max Decel Enleanment = 2.0 ms
- Total Maximum PW = 2.0 ms
Decel Decay Table
The Decel Decay Table controls the rate of decay or how quickly the removed decel fuel is returned as a percentage of an engine cycle
Example:
Decel fuel start value = 10ms
Decel decay = 10%
Decel fuel will decay back to zero 10% per engine cycle
Cylinder Fuel Trims
Cylinder trims are used to apply fine fuel corrections on a per-cylinder basis in order to improve combustion balance across all cylinders. Even in well-calibrated engines, small differences in airflow distribution, injector flow characteristics, and combustion efficiency can result in uneven cylinder operation.
Typical reasons for using cylinder trims include:
Balancing EGT distribution across all cylinders to reduce thermal stress
Correcting minor airflow or volumetric efficiency differences between cylinders
Compensating for injector flow variation or ageing effects
Improving overall engine smoothness and combustion consistency
Reducing the risk of individual cylinders running lean or rich under load
Cylinder trims can be enabled per cylinder and provide a ± fuel mass percentage correction via a 3D table.
Table Control
Cylinder Trims are enabled from Fuel -> Cylinder Fuel Trims -> Cylinder Trim Table Control
OFF – The Trim Table is Off ON - The Trim Table is On
Each trim table will appear individually under Fuel -> Cylinder Fuel Trims
Fuel Bank Trims
Overview
Bank Trims allow fuel mass percentage corrections to be applied independently to each cylinder bank.
Each cylinder can be assigned to either Bank 1 or Bank 2, enabling separate fuel control for grouped cylinders.
Bank 1 and Bank 2 each include a dedicated 3D correction table, used to apply fuel compensation based on engine operating conditions such as engine speed and load.
These trims are typically used to correct for bank-to-bank fuel distribution differences, sensor tolerances, or airflow imbalance between intake paths.
ℹ️ Important
Cylinder-to-bank assignment is required for this function. Each cylinder must be mapped to either Bank 1 or Bank 2 to ensure accurate fuel trim application across all cylinders.
See Config -> Engine Setup -> Bank Cylinder Setup
Table Control
Bank Trims are enabled from Fuel -> Bank Fuel Trims -> Bank Trim Table Control
OFF - The Trim Table is Off ON - The Trim Table is On
Fuel Compensations
Compensations
All Fuel Compensations (other than Charge Temperature Estimate and Charge Temperature Offset) are percentage compensations added/subtracted onto Final Fuel Mass calculations :
Fuel Mass Final Uncorrected = 0.0367g
Injector Mass Flow = 309 g/sec
User Comp 1 = +19.5%
Fuel Mass Final Corrected = 0.0367 x 1.195 = 0.0438g
Effective Pulsewidth Effective = Fuel Mass Final Corrected x (1/Injector Mass Flow )x 60
Effective Pulsewidth Effective = 0.0438 x 1/309 x 60 = 8.515ms
Compensation Tables
Fuel Sec Load (Secondary Load Compensation) can be turned on/off.
The compensation can be turned on/off or be selected to be on via a User Function (only active when User Function is active).
OFF – The Compensation Table is Off
ON – The Compensation Table is always On
User Function 1-10 – The Compensation Table is on only when the selected User Function is Active
MAF Scaling – The Compensation is a “Scaler” (in %) of the MAF signal * Used for Sec Load Table
Secondary Injection Balance Table
Overview
The Secondary Balance Table defines how the total fuel required for each injection event is divided between the Primary and Secondary injectors.
Table values are expressed as a percentage (%) and represent the proportion of the total fuel volume delivered by the Secondary injectors. The remaining fuel is automatically delivered by the Primary injectors.
Table Values
Value
Fuel Distribution
0%
0% Secondary injectors, 100% Primary injectors
50%
Equal fuel volume delivered by the Primary and Secondary injectors
100%
100% Secondary injectors, 0% Primary injectors
Intermediate values proportionally divide the required fuel between the Primary and Secondary injectors.
ℹ️ Note
The Secondary Balance Table controls the fuel volume distribution between the Primary and Secondary injectors. The ECU automatically calculates the individual injector pulse widths based on the injector flow rates and the configured Secondary Balance value to achieve the required total fuel delivery.
When the Primary and Secondary injector flow rates are correctly configured and calibrated, changing the Secondary Balance value should have little or no effect on the overall engine air-fuel ratio
Example 1:
Operating Conditions
Primary Injector = 1000 cc/min
Secondary Injector = 1000 cc/min
Required Total Injector Flow = 20.000 ms
Balance Table = 50.0%(Equal flow from both injectors): Primary Injector Flow = 10.000ms
Secondary Injector Flow = 10.000ms
Balance Table = 25.0%( 25% of the flow supplied from Sec Injectors): Primary Injector Flow = 15.000ms
Secondary Injector Flow = 5.000ms
Balance Table = 75.0%( 75% of the flow supplied from Sec Injectors): Primary Injector Flow = 5.000ms
Secondary Injector Flow = 15.000ms
Example 2:
Operating Conditions
Primary Injector = 1000 cc/min
Secondary Injector = 2000 cc/min
Required Total Injector Flow = 20.000 ms
Balance Table = 50.0%(Equal flow from both injectors): Primary Injector Flow = 10.000ms
Secondary Injector Flow = 5.000ms
Balance Table = 25.0%( 25% of the flow supplied from Sec Injectors): Primary Injector Flow = 15.000ms
Secondary Injector Flow = 2.500ms
Balance Table = 75.0%( 75% of the flow supplied from Sec Injectors): Primary Injector Flow = 5.000ms
Secondary Injector Flow = 7.500ms
⚠️ Note
Ideally you want to adjust the the Balance Table so the pulse width and hence duty cycle is the same for both Primary and Secondly Injectors. To calculate the Balance value use the following formula:
Configure the type of Ethanol sensor used within Emtune software, Tuning -> Engine Functions -> Ethanol Sensor -> Setup
0: GM / Continental
1: FORD
Verify the operation of the Ethanol sensor by pulling up the run time variables by pressing the shortcut key F3 and selecting the Fuel 2 tab.
Step 2
Configure the VE fuel model to load the Ethanol % compensation tables: (Fuel Density Table and Stoichiometric Custom Table)
Preconfigured templates/copies of these tables are included within the Emtune installation package and can be found in the folder C:\Emtron\Table Files
To load these preconfigured tables simply right click within the current table you wish to change and select “Load Table” and browse to the file location listed above.
The below tables allows the ECU to accurately make adjustments injector pulse widths based on the characteristics of ethanol based fuel and its different % blends with Gasoline.
To configure this table to go Config-> Fuel -> Fuel Density Table
Configure the custom stoichiometric table which also is based on the Ethanol % of the fuel
To configure this table to go Config-> Fuel -> Stoichiometric Custom Table
Step 3
Next we go onto configuring the Z-Axis control on the Main Ignition Tables.
This allows the tuner to have the ability to manipulate the tune based on the Ethanol Content % value provided by the flex fuel sensor. This Z-Axis (ethanol %) is used to determine the % blend between the two Main Ignition tables.
Tuning -> Ignition -> Ignition Table Control -> Main Ignition Tables
Set the Ignition table control to 6: ON –Z-Axis.
This will activate the Main Ignition Tables1-3 as well as the Ign Main Table Z-Axis Setup table.
Step 4
Go to Tuning -> Ignition -> Z-Axis Setup -> Ign Main Table ZAxis Setup
Configure the Ign Main Table Z-Axis setup table such that the X-Axis parameter is Ethanol Content %. (Shortcut key A to access axis setup)
This table controls the percentage of blend used by the ECU between the Main Ignition tables.
A value of 1.0 = use 100% Main Ignition Table1 (Gasoline / pump gas Ignition Table)
A value of 1.5 = use the average value of Main Ignition Table 1 and Main Ignition Table 2
A value of 2.0 = use 100 % percent of Main Ignition Table 2 (E85% tune Ignition table)
The engine should be tuned on 100 % Gasoline (pump gas) and E85 separately and the appropriate Ignition tables populated before attempting to tune any Z-Axis setup tables.
Steps 2 -4 can and should be repeated for other aspects of a Flex Fuel tune. These include:
Starting Enrichment compensation tables
Boost Target Table Control
Map Limit Table Control
Lambda Target Tables
Any table within the ECU that can be spanned against Ethanol Content %
NB:
The VE fuel table should not need any compensation based on Ethanol Content as the Fuel Model accounts for this.
Should you need to make corrections Ethanol % then the Fuel Mass Modifiers table could be used to correct for any inaccuracies in the fuel model. Such causes of error could be attributed to incorrect injector data, inaccuracies in the Flex Sensor and any other sensors in the system the ECU relies on to create an accurate model.
To enable the Fuel Mass Modifier table to go Tuning -> Fuel -> Fuel Table Control -> Fuel Modifier Tables
Enable the Fuel Mass Modifer Table Control set value to 1
Configure Fuel Mass Modifier Table such that Ethanol Content % on the X-axis and Efficiency Calculation % on the Y-axis Shortcut key (A) to configure table axis. Eg below shows Fuel Mass Modifier Table with percentage trims being applied to the Main VE Fuel Fable
Fuel Modifier Tables
Fuel Modifier tables can be turned on/off.
These tables compensate the raw air mass or fuel mass calculation within the model
OFF – The Compensation Table is Off
ON - The Compensation Table is On
Each compensation table will appear individually under Fuel -> Fuel Modifier Tables
Fuel Mass Modifier Table"
Fuel Mass Modifier Table is enabled via : Tuning -> Fuel Table Control -> Fuel Modifier Tables
Values in this table modify the ECUs Final Fuel Mass directly as a percentage
Z-Axis Setup
Z-Axis Setup
A Z-Axis function allows for a definable blend or swap based on a definable X Axis parameter.
The available Fuel Z-Axis table functions are enabled via Fuel Table Control
Once enabled, the Z-Axis is defined by the user
Right mouse click on the table to enter Table Axis setup
Within the Axis setup, any runtime can be selected and utilized as the X Axis
% Ethanol Content runtime shown as an example above
