The 2.0l EA888 motor found in the mk7/7.5 GTI, Golf R, A3, and S3 has always been a pretty stout platform, responding well to basic upgrades, as well as larger turbo sizes. The ECU however has always been a bit complicated and fiddly to deal with, as it has a lot of tables and functions that all need to work in harmony together in order to control boost pressure safely. As a result we’ve created the CCF Basic Boost (BB) feature, reducing the number of tables you’ll need to set up in order to get up and going on a new turbo.

Basic Use and Setup

Activating the Basic Boost system is as simple as opening the folder and enabling the master switch by setting the table value to 1 . At that point it will no longer use a few of the factory tables (Listed below)

Wastegate Setpoint

The new CCF Basic Boost system uses a feed-forward wastegate duty cycle map called Basic Boost Wastegate Setpoint. This map uses engine speed and desired PUT Setpoint to calculate a target wastegate position which is adjusted to maintain the target as-needed by the Wastegate PID tables.

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If you already have a tune for your current turbo populated, you can populate this table to relatively close values easily by logging RPM, Wastegate Position and PUT Target. This should give you all you need to populate this table with relatively close values.

Basic Boost Wastegate Control Feedback Systems

While the Basic Boost feed forwards wastegate control works the best if the wastegate position/PUT target/RPM relationship is relatively close to the desired output, errors for this system are corrected very well by the factory PID control.

In the below example the Basic Boost wastegate setpoint wasn’t set to the correct values for the desired boost, as a result you can see the factory PID control taking over to hit the Basic Boost PUT Limit

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Basic Boost wastegate position in red and final wastegate position after PID control in green. This shows the factory PID control adjusting wastegate setpoint in order to hit targeted PUT

In the log above you can see the BB wastegate position and the corrected wastegate position. Once the BB Wastegate Setpoint was adjusted you can see the PID control system is much less active, but the PUT target is still achieved.

Adjustment Factors for BB Wastegate Setpoint (Duty Cycle)

CCF Basic Boost adds 2 additional compensation tables for the boost control system.

• Ambient Pressure Factor on WGDC this table adds a multiplier which allows you to make adjustments to the targeted wastegate duty cycle (setpoint) for differences in elevation/atmospheric pressure

• Ambient Temperature Factor on WGDC Compensation multiplier which will adjust wastegate duty cycle (setpoint) depending on the ambient temperature outside the car. This can help to reduce overboosting in cold weather or reduce power in hot temperatures to prevent engine damage.

Defined PUT Limit (Target)

The final PUT setpoint targeted by the system will be determined by the stock torque and airflow system but is ultimately limited by the Basic Boost table Basic Boost PUT Limit. This 3d table chooses a limit based on RPM and Gear (which also means you now get specific boost targets for every gear!).

The final PUT set point for the vehicle will be the one determined by the boost control system until it hits or exceeds the Basic Boost Put Limit, at which point that will be come the new limit until the target drops below the limit again.

Keep in mind the final PUT target is also going to be determined by the torque model and the rest of the factory system. This is because the amount of airflow/boost being requested will impact the torque being generated, and boost pressure is adjusted based on the amount of torque being requested by the driver. As a result under many conditions it’s possible that your Basic Boost PUT Limit won’t be used.

RPM and Gear Based Limits

With the new PUT set point limit table, you are given more flexibility in order to fine tune the boost curve for each gear to optimize traction, safety etc. (though keep in mind this limit is only used when the factory limit is higher than this number)

Basic Boost and Flex Fuel

In order to keep up with the changes to fueling and knock resistance on higher concentrations of ethanol, we’ve also added flex fuel versions of the Basic Boost system.

Flex Fuel Basic Boost PUT Limit

The Flex Fuel table sets a target that is used when you are using 100% of the blend percentage, while the “regular” Basic Boost PUT Limit table is used at 0%. As you increase the blend percentage, more of the Flex Fuel Basic Boost PUT Limit is added to the target.

The blend percentage chooses how much of the Flex Fuel Basic Boost PUT Limit will be used to set the final BB PUT Limit. This is being done on a car with a larger turbo and stock fuel system so we intentionally dialed back power output on higher ethanol content to ensure safe operation of the vehicle in the 100 degree weather here in texas.

Flex Fuel Basic Boost Wastegate Setpoint

Enabling Flex fuel and Basic Boost activates a second wastegate setpoint table used for high ethanol. In many cases higher ethanol requires different boost control strategy and a different wastegate feed forward table is used. Here, a second wastegate feed forward table allows this approach and this table can be blended as a function of ethanol content just like the PUT setpoint Limit tables.

Very similar to the Flex Fuel Basic Boost PUT Limit, this establishes a new wastegate position when using the flex fuel system, then uses a percentage of it based on what the current ethanol content of the fuel being used is. The Flex Fuel table sets a target that is used when you are using 100% of the blend percentage, while the “regular” Basic Boost Wastegate Setpoint table is used at 0%. As you increase the blend percentage, more of the Flex Fuel Basic Boost Wastegate Setpoint is added to the target.

Links

MQB Flex Fuel Tuning Guide