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G4+ Storm Closed loop lamda PID?


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Hello,

I am not able to find if the ECU has this feature. Is there a PID algorithm available for closed loop lamda? Right now the afr value is oscilating around 14.7 which is normal, like the OEM ecu used to do.

 

But I've seen other ECUs like the Megasquirt which uses PID for CLL and is able to keep the afr steady at 14.7-8..

 

Is this available?

 

Thank you

Peter

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Closed Loop Lambda (CLL) is designed to provide automatic trimming of fuel mixtures.  This is required for best emissions and catalytic converter operation.  Link G4+ ECUs allow the use of Wide Band or Narrow Band exhaust oxygen sensors.

 

CLL can operate in the following modes:

 

· Stoich Mode (Narrow Band) - Narrow Band Stoich Mode CLL will continually trim fueling to try and achieve a constant voltage from the oxygen sensor.  Typically this is the voltage that the sensor delivers at the stoichiometric Air Fuel Ratio (AFR) (usually 14.7:1 for petrol).  In this mode CLL is usually set up to operate only under cruise and light load conditions.  This mode must be used if only a narrow band oxygen sensor is fitted.
· Stoich Mode (Wide Band) - Wide Band Stoich Mode CLL will continually adjust fueling to try and make measured AFR match the value in the AFR Target Table.  In this mode CLL is usually set up to operate only under cruise and light load conditions.  This mode should be used if a wide band oxygen sensor is fitted.

 

Warning:  CLL is designed to be used to apply a minor trim while the vehicle is being driven.  It is not intended as a tuning aid.  Assisted fuel tuning can be done using the Quick Tune function.

 

To use CLL a narrow band oxygen sensor or wideband oxygen sensor controller must be correctly wired to an Analog Voltage Input.  The Analog Voltage Input must be configured as NB Oxy or Wideband as appropriate.  When using a wideband sensor make sure the analog channel is calibrated to match the sensor controller.

 

Note:  If a heated oxygen sensor (narrow band) is used, its heater may be controlled by the ECU using an Auxiliary Output.

 

 

How It Works:

 

Stoich Mode

 

Given a target oxygen sensor voltage (Narrow Band mode) or AFR (Wide Band mode), the ECU will progressively increase the fuel trim value when the oxygen sensor reads lean.  Likewise, the ECU will decrease the fuel trim value when the oxygen sensor  reads rich.  The result is an AFR continuously cycling around the target point, this is also known as dithering and is often required for correct catalytic converter operation.

 

Lockouts

 

Lockouts are provided to prevent CLL from operating under various conditions.  Typically lockouts are set to ensure that:

 

· CLL only operates after the sensor is properly heated and reading.
· CLL only operates while the engine is running under cruise or light load.
· CLL is temporarily disabled during transient or overrun conditions.

 

Sensor Locating

 

If using a Narrow Band oxygen sensor it must be installed in a location where it can measure the mixed exhaust gas from all cylinders (only a single sensor is used).  When using a Wide Band oxygen sensor, one or two sensors can be installed.  The CLL function uses the Wideband Average parameter for control.

 

 

Adjustments

 

  The following settings are provided to configure CLL:

 

All Modes

· Lambda Mode - CLL operating mode.
· ECT Lockout - CLL will not operate below this engine coolant temperature.
· Timer Lockout - CLL will not operate for this many seconds after startup.
· RPM Lockout High - CLL will not operate above this RPM.
· RPM Lockout Low - CLL will not operate below this RPM.
· MAP Lockout - CLL will not operate above this MAP value.
· FTrim Limit +/- - Maximum amount by which CLL can adjust fuel values.

 

Stoich Mode (Narrow Band)

· Gain Control - Controls the rate at which CLL tries to correct AFR.
· Analog Channel - The channel that the oxygen sensor or wideband controller is wired to.
· Dither Voltage - Target oxygen sensor output voltage, typically 0.45 volt.

 

Stoich Mode (Wide Band)

· Gain Control - Controls the rate at which CLL tries to correct AFR.

 

 

The status of the Closed Loop Lambda system can be viewed under the Fuel runtime values tab.  Status values are as follows:

 

· OFF - CLL is turned off.
· Increase Fuel - Increasing the fuel trim.
· Decrease Fuel - Decreasing the fuel trim.
· Target Reached - Target AFR matches Actual AFR (Auto Mode only).
· Max Clamp - Fuel value has been increased as much as possible.
· Min Clamp - Fuel value has been decreased as much as possible.
· Lockout: RPM < 500 - Engine RPM too low, CLL disabled.
· Lockout: ECT - ECT is below ECT Lockout value, CLL is disabled.
· Lockout: Startup Timer - Timer Lockout has not expired yet, CLL is disabled.
· Lockout: RPM High - RPM is above RPM Lockout High value, CLL is disabled.
· Lockout: RPM Low - RPM is below RPM Lockout Low value, CLL is disabled.
· Lockout: MAP - MAP is above the MAP Lockout value, CLL is disabled.
· Lockout: Anti-Lag - Anti-lag is active, CLL is disabled.
· Lockout: Fuel Cut - Overrun Fuel Cut is active, CLL is disabled.
· Accel Active - Acceleration Enrichment is active, CLL is disabled.
· No Signal - Oxygen sensor voltage has been below 0.05 volts for over 15 seconds, CLL is disabled (Narrow Band only).
·

 

 

 

 

 

Lambda Mode

 

  Lambda Mode sets the current CLL operating mode.  Operating modes are described in detail above.

 

 

ECT Lockout

 

This prevents CLL operating below a particular coolant temperature.  This avoids having CLL active while warm up enrichment is still being added.  Set this value to about 5 degrees below the normal operating temperature.

 

 

Fuel Trim Limit +/-

 

  This is the maximum amount by which fuel will be increased/decreased.  A typical value is about 15%

 

 

Gain Control (Stoich Modes only)

 

  Gain Control sets the rate at which fuel is increased/decreased.  A too high gain value will result in large swings about the stoichiometric point, while a too low gain will result in very slow correction.  A typical gain value is 2.

 

 

RPM Lockout Low, RPM Lockout High

 

  RPM Lockouts provide a means by which CLL can be disabled outside a particular RPM range.  Typically the RPM Lockout Low will be set well below the idle RPM to ensure CLL is active at idle.  In some applications an AFR of 14.7:1 can result in an unstable idle.  In this case, set RPM Lockout Low well above the idle RPM.

 

 

MAP Lockout

 

MAP Lockout sets the MAP value at which CLL will be disabled above.  This allows CLL to be disabled under power.  A typical value is about 70 kPa.

 

 

Timer Lockout

 

The Timer Lockout provides a means by which CLL can be disabled for a time period after start up.  This ensures that all startup enrichments are inactive before CLL is enabled.  It also ensures that the oxygen sensor is up to temperature.

 

 

Analog Channel (Narrow Band only)

 

This is the analog voltage channel that the narrow band oxygen sensor is wired to.

 

 

Dither Voltage (Narrow Band only)

 

  The Dither Voltage is the voltage output by the oxygen sensor at the stoichiometric point (AFR 14.7:1 for pump fuel).  This value is typically set to 0.45 Volt.

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