Throttle Body Setup

Overview

The throttle body model is a key component to unlocking the advanced tuning features of the Emtron ECU. That is Throttle Mass Flow & Torque Modeling & Management. The accuracy of your setup in the throttle body mode is critical for good results. The Throttle Body setup consists of 2 main parts:

• Throttle body diameter and scaler.
• Throttle body area table. See the TMF Setup help topic for more information.

Settings are adjusted from the Config -> Air Mass -> Throttle Mass Flow(TMF) Setup menu. Throttle body templates are also available to load into the ECU from the File -> Import Module File menu

See the DBW Torque Management help topic for more information on the process of converting Pedal Position to Throttle Area to DBW Servo target.

Throttle Body Area Table

See the Throttle Area Table help topic for more information.

Throttle Body Area Table

Overview

The Throttle Body Area Table is a 40-cell calibration table that defines the relationship between Throttle Plate Position (Servo Position) and the corresponding effective Throttle Area.

The table describes how much effective area is available for air to flow through the throttle body at each throttle plate position. This relationship is determined by the physical design of the throttle body and is not linear.

The ECU uses this relationship to:

• Convert a Pedal Throttle Area demand into the corresponding Servo Position used as the DBW Target.
• Determine the effective throttle area available at a given Servo Position for Throttle Mass Flow (TMF) calculations.

Accurate calibration of this table is critical to Throttle Mass Flow calculations and therefore to ECU functions that depend on accurate throttle airflow estimation, including:

• Idle Control
• Cruise Control
• Torque Management
• Throttle Control
• Air Mass Modelling

See the TMF Tuning help topic for more information on Throttle Mass Flow Tuning.

Example:

Pedal Throttle Area Demand = 4.37%

Using the table in the below image, the ECU would find the 4.37% area and correlate this to 9.0% Servo Position. The DBW Servo Position Target therefore becomes 9.0%

i.e the ECU is asking for 4.37% area and moves the throttle plate to 9.0% servo position to achieve this.

Nissan GT-R R35 Throttle Body Area table is shown above.

**Throttle body templates are also available to load into the ECU from the File -> Import Module File menu

There are multiple ways to calibrate the appropriate throttle area.

Method 1 – MAF verification

If the application is using a calibrated MAF sensor. Then the throttle area % can be adjusted and matched to TMF air mass VS MAF air mass at different throttle/DBW servo positions.

Method 2 – Matching Lambda

If no MAF sensor is available, setting fuel trims to 0 (or near 0), you can adjust the throttle area to match the target mixture very quickly.

** The only way to truly validate error in the TMF calculation is to use Method 1

** Some extreme applications where live Lambda is unstable may be more difficult to map with Method 2

See Torque Management Tuning Guide, Throttle Mass Flow, and Torque Reduction (throttle) sections for more specific information, and guides on how to tune.

TMF Idle Speed Control

Introduction

Throttle Mass Flow (TMF) as the name indicates, is the rate at which air mass is flowing through a throttle body in units of grams/second (g/s).

The flow through a throttle body is governed by three physical elements:

1. Conversation of mass
2. Newtons second law of motion for fluids
3. Conservation of energy

By combining all these elements the ECU can model the flow of fluid through the throttle body accounting for throttle plate thickness and throttle shaft size. One key piece of data is knowing the pressure ratio across the throttle body as shown in the below diagram, the other key piece of data is the current throttle area. If the pressure ratio and throttle area is known, the ECU can very accurately calculate the mass flow rate through a throttle body.

Although the ECU completes these complex calculations internally, the process of calculating Throttle Mass Flow is kept as simple as possible for the user with the following inputs and setup required:

Inputs required

1. Pressure Before the throttle Plate
2. Pressure After the throttle Plate

Setting required

1. Throttle Body Size
2. Throttle Area to Servo Position Correlation Table (Throttle Body Area Table)

The TMF calculation can summarised in the below equation :

Throttle Mass Flow Idle Speed Control

The Throttle Mass Flow (TMF) idle speed control function delivers extremely accurate and rapid idle calculation based on actual engine’s airflow requirements. Any engine load change will be detected by a pressure ratio change across the throttle body allowing the ECU to make instantaneous corrections. In all DBW applications we strongly recommend that the TMF Idle speed control is employed. TMF Idle speed control is an independent idle speed control function that utilises the Emtron’s comprehensive air mass flow modelling without effect on the fuel model used.

The Throttle Mass Flow (g/s) becomes the target flow for the Idle Speed Control system i.e how much air mass flow is required for a given target rpm. So the TMF becomes the feed-forward/Initial value. The ECU will then apply a PID correction to this flow target until the Target RPM is reach. By rearranged the TMF equation, the ECU will convert the final Throttle Mass Flow(g/s) into Throttle Area and move the plate to that position. A feed-forward/Initial value table example is shown below.

Typical TMF Idle Feed forward table in units of g/s

NOTE:

Any fuel model mode can be selected and does not need to include TMF for the TMF idle speed control function to work correctly.

TMF fuel model is covered in the Fuel section and not discussed here.

Warning - DBW setup must be completed before setting up TMF idle

Throttle Mass Flow Tuning

Overview

Throttle Mass Flow (TMF) as the name indicates, is the rate at which air mass is flowing through a throttle body in units of grams/second (g/s). Using the throttle body size, throttle area, temperature, pre and post throttle pressures,the ECU can very accurately calculate air flow through the throttle body and therefore into the engine; this is known as the TMF Calculation. Other sensors that also generate air mass flow (g/s) data are Manifold Pressure and MAF sensors. The TMF Calculation is just another method of determining air mass flow and has benefits over MAP and MAF as discussed further down.

The image below illustrates the basic elements required to calculate TMF.

Getting into more detail, the flow through a throttle body is governed by three physical elements, Conversation of mass, Newtons second law of motion for fluids and Conservation of energy. By combining these elements the ECU can model the flow of fluid through the throttle body accounting for throttle plate thickness and throttle shaft size. By then including real-time data such as the pressure ratio across the throttle plate and the instantaneous throttle area, the ECU can precisely calculate the mass flow rate through a throttle body.

Although these calculation are complex, the TMF setup process for the user is kept as simple as possible with the following inputs and setup required:

Example: TMF Airflow Validation and Blending Workflow

Use the following workflow to validate TMF airflow, calibrate the Throttle Body Area Table, and correctly blend TMF with alternative air-mass calculation methods.

1. Base Engine Setup

Ensure the fundamental engine configuration is correct before beginning TMF calibration.

• Engine displacement
• Injector data
• Engine configuration and cylinder setup
• Other parameters required for accurate air-mass and fuel calculations

2. Throttle Body Setup

Ensure the throttle body configuration and control are correctly established.

• Correct throttle body size and configuration
• Throttle position calibration
• Throttle control PID tuning fully validated
• Throttle operation stable and repeatable across the operating range

3. Sensor Configuration and Calibration

Verify that all sensors required by the TMF model are correctly selected, assigned, calibrated, and installed.

• Pre-throttle MAP

  • Correct sensor assignment
  • Correct calibration
  • Correct physical installation and pressure reference

• Post-throttle MAP

  • Correct sensor assignment
  • Correct calibration
  • Correct physical installation and pressure reference

• IAT

  • Correct sensor assignment
  • Correct calibration
  • Correct sensor location

4. Enable and Configure TMF

Once the engine, throttle body, and sensors have been validated:

• Select and assign the correct sensors.
• Enable the TMF Air Mass Model.
• Verify that all required TMF inputs are valid and responding correctly.
• Confirm that the calculated TMF airflow is reasonable before proceeding with calibration.

5. Air Mass Model

• Select the required Air Mass Model.

6. Outflow Function

The Outflow function drives the TMF calculation at pressure ratios near 1.0. See the help article on TMF Outflow for more detail.

If the Outflow Reference and Outflow Measured values are scaled correctly, the Throttle Air Mass will read very close to MAP Air Mass (speed density) as above. With correctly scaled Outflow, it’s possible to use TMF 100% of the time (though this may not always be desirable).

The main thing to tune here is the Outflow Reference Scaler:

• Outflow Reference uses (references) the VE value, so before setting the scaler, ensure that the MAP Air Mass, at least near pressure ratios of 1.0, is accurate.
• Adjust the Outflow Reference Scaler so that the Throttle Air Mass is the same as or just slightly under the MAP Air Mass.

In the above image:

• At lower Throttle Effective Area & Throttle Pressure Ratio’s, Outflow Measured is highest and is driving Outflow Final.
• Near pressure ratio’s of 1.0, Outflow Reference is highest, and takes control of Outflow Final.
• At WOT, where Outflow Reference is dominant, the Reference Scaler is set so that Throttle Air Mass is very close to MAP Air Mass.
• The Air Mass Model Blending Table is dictating Air Mass Final:
  • Low Throttle Area / Pressure Ratio: Air Mass Final = Throttle Air Mass.
  • High Throttle Area / Pressure Ratio: Air Mass Final = MAP Air Mass.

A correctly configured TMF Outflow Reference Scaler should also translate to torque calculations. Torque can also be used as a “compare” channel. In some cases, this allows you to validate torque calculation, frictional losses, etc - at the same time.

7. Air Mass Model Blending Table

This table controls where the Air Mass Final runtime comes from:

• 0.0% = Air Mass Model Calculation 1 (eg: Speed Density)
• 100% = Air Mass Model Calculation 2 (eg: Throttle Mass FLow (TMF))
• 50.0% = Interpolate half way between Calculation 1 & Calculation 2.

Non Conventional VE Tables

Depending on the specific application, and the throttle area demand/effective area vs pressure ratio, you may find that all of, or most of the part-throttle SD VE table is no longer necessary. This allows for non-conventional VE tuning to be used. In many cases, the entire load axis of the VE table can be turned off (or set to something other than MAP/Load) as it’s no longer needed.

An example of a non-conventional VE table. This engine runs in TMF below WOT. As WOT approaches it blends into Speed Density. The cam position is dynamically accounted for in the VE table. The expansion ratio correction is used to account for changes in VE as boost increases.
As an added bonus, tuning this way informs the optimal cam position by following the high spots in the VE table.

8. Tuning the Throttle Body Area Table

The Throttle Body Area table tells the ECU how much actual throttle area exposed to flow air at different throttle positions. The relationship to throttle position is not linear. This is key to the ECUs Torque Management functions, as accurate air mass measurement and actual engine torque go hand in hand.

For torque management, Throttle Area Demand can be manipulated which will be directly proportional to air mass when this is configured correctly

This 2D table is all that is needed to appropriately map the given throttle area vs throttle position. As mentioned previously, this allows for extremely fast and accurate mapping of the engine when TMF is active.

There are multiple ways to calibrate the appropriate throttle area:

Method 1 – Matching Lambda

• Ensure fuel trims are 0 and closed loop lambda is off.
• Blend the fuel model into 100% TMF.
• Hold the engine at a stead state, high enough that air flow is reasonable stable (eg: 3000 RPM).
• Adjust the throttle area table so that measured Lambda matches Lambda Target.

Method 2 – Matching other forms of Air Mass measurement

If the application is using a calibrated MAF sensor. Then the Throttle Area % can be adjusted and matched to so that Throttle Air Mass matches MAF Air Mass at different throttle/DBW servo positions. The same can be done matching Throttle Air Mass to MAP Air Mass.

9. Validating Throttle Area Torque

Another way to validate Throttle Area and TMF Torque, is to force the ECU into a “Torque Management” function. The Calibrate Throttle Area setting in Throttle Mass Flow Setup does exactly this. It allows you to set a fixed throttle torque limit (eg: 300nm). When this torque limit is driven into, the ECU will use TMF and the Throttle Area Table to try and limit the engine torque to the configured value.

Once a torque limit is set, the “Engine Torque TMF” channels should match the standard Engine Torque channels, otherwise the Throttle Area table is incorrect.

Example of where Engine Torque TMF and Engine Torque are not matching due to incorrect Throttle Area settings.

Corrected Throttle Area table so Engine Torques further aligned.

10. TMF Correction Table

This correction table essentially exists to help remove an error remaining in the system across a wide variety of load & rpm conditions. Start with the whole table set to 0, and adjust if necessary.

Throttle Mass Flow Outflow

Overview

The Outflow Function describes the relationship between the pressure ratio across the throttle and the amount of air that can flow through it.

As the pressure ratio changes, the relationship between pressure and airflow also changes. The Outflow Function models this behaviour and forms a critical part of the modelled throttle body fluid dynamics used in the TMF (Throttle Mass Flow) calculation.

See the TMF Setup help topic for more information on Throttle Mass Flow Setup.

See the TMF Tuning help topic for more information on Throttle Mass Flow Tuning.

The ECU calculates two Outflow values:

• Outflow Measured - Directly calculated from the Throttle Pressure Ratio.
• Outflow Reference - Generated by referencing the engine’s rpm, VE at an assumed pressure ratio of 1.000.

The Outflow Measured value can become unstable as the Throttle Pressure Ratio approaches 1.000. To maintain a stable and accurate TMF calculation, the ECU can blend the Outflow Reference value into the calculation in this region. The blend will start when the Outflow Reference becomes higher in value than Outflow Measured.

In summary, the TMF calculation blends between Outflow Measured and Outflow Reference under various conditions.

Outflow Reference Scaler

The TMF Outflow Reference Scaler scales the Outflow Reference value. The goal is for the ECU to smoothly transition to the Outflow Reference when the Outflow Measured value becomes unstable.

There are many contributing factors to the scaler value, but the single biggest one is the number of cylinders:

Typical values:
4 Cyl = 24.0 - 28.0
6 Cyl = 18.0 - 22.0
8 Cyl = 10.0 - 14.0

Outflow Measured Correction Table

The TMF Outflow Measured Correction Table allows the Outflow Measured value to be scaled using a percentage correction. The primary purpose of this correction is to apply a negative adjustment, reducing the Outflow Measured value and allowing the Outflow Reference value to be blended into the TMF calculation earlier.

Tuning

For more information on tuning both the Outflow Measured and Outflow Reference, refer to Section 6 in TMF Tuning