Closed Loop Advanced

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Warning: These are advanced tables and only should be altered by experienced tuners.  Leaning out the target lambda will result in increased exhaust gas temperatures.

 

WOT (Full Load) Fuel Compensation

 

From the factory all the fuel tables are tuned to a stoichiometric air/fuel ratio (lambda 1, nominally 14.7:1 AF). Because the engine needs to fun richer than lambda 1 under load, the fuel is increased at full load (wide open throttle or WOT) by using WOT compensation tables.

The WOT tables are replaced by the target lambda tables when the target lambda option is selected.

 

fuel-wot-compensation

 

No WOT compensation

No fuel compensation is made either in open or closed loop, using either WOT compensation tables or target lambda tables.

 

WOT compensation fixed at lambda 0.85 (12.5:1)

Fuel is compensated in open loop using a fixed compensation value of lambda 0.85.

 

WOT compensation from WOT compensation tables

Fuel is compensated in open loop using the WOT compensation tables.

 

Fuel compensation from target lambda tables

Fuel is compensated in both open and closed loop using the target lambda tables. This means that if you change the target lambda tables you do not need to change the fuel tables in order to see a change in lambda.

 

WOT compensation tables

There are two sets of compensation tables for the low and high speed cams - normal and catalyst protection.  The catalyst protection tables are used when the ECU determines the catalytic converter is likely to be very hot. Note that these tables are not target lambda tables, but the extra amount of fuel to inject is based on the main fuel tables being lambda 1.

 

fuel-wot-comp-table

 

Closed Loop Target Lambda (KPro4)

The KPro4 can replace the WOT compensation tables with true target lambda tables, which can use used at full load.

fuel-target-lambda

To run closed loop under full load or boost, select 'Enable target lambda tables' and increase the 'Maximum MAP for closed loop'.

 

Target Lambda Tables

Target lambda tables are used in closed loop for the lambda target and both in open and closed loop at fuel compensation (similar to WOT compensation). Changing the target lambda table will also change the fuelling. This way the lambda can be changed without needing to change the main fuel tables.

target-lambda

Closed Loop Under High Load / Boost

 

To run closed loop under full load or boost:

Disable 'WOT compensation fixed at lambda 0.85'.
Enable 'target lambda tables'
Set 'Maximum MAP for closed loop' to the highest MAP you want to run closed loop in.
Set 'Closed Loop Max TPS' tps values 100%

 

Closed Loop Target Lambda (ECT)

These tables control the target lambda (air/fuel ratio) under closed loop.  The target lambda may be monitored from the AFCMD sensor.

 

closedloop-target-lambda

 

Three tables are used to determine the target lambda - two tables at different load points (Target Lambda ECT Low and Target Lambda ECT High), and a final limit table (Target Lambda Limit).

 

The target lambda is calculated by reading the Target Lambda ECT Low and High values, and then interpolating between the values by engine load (MAP) with loads points at approximately 32 kPa for the low table and 82 kPa for the high table. The lower (richer) of the this interpolated value and the Target Lambda Limit are used for the target lambda.

 

To lean out closed loop operation first increase (lean out) the limit table, then increase the target lambda.

 

closedloop-target-lambda-lean

The above highlighted changes will result in a normal target lambda while warming up; leaner (15.5:1 or 1.05 λ) at light load (~ 32 kPa), changing to stoichiometric (14.7 or 1.0 λ) at high load (~82 kPa).

 

Leaning the lambda out past stoichiometric will give higher cylinder and exhaust gas temperatures, which may damage the engine / catalytic converter / exhaust system.  It is not recommend to run leaner than stoichiometric when using a catalytic converter.