With a big facelift, mild handling changes, and a revised version of the 2.0L turbocharged engine and 7-speed DSG we all know and love on the MQB platform, the new GTI/Golf/S3 are a pretty potent addition to the Volkswagen family. Assuming you can get past the haptic buttons and some of the small nagging issues that have been common on these cars (check out our page https://cobbtuning.atlassian.net/wiki/spaces/PRS/pages/2734882817) These cars provide an even better starting point than the previous generation.

Much of the tuning is similar to the earlier MK7/7.5 vehicles however it’s trending towards a greater overlap with the ECU utilised in the newer Porsche and Audi cars. All the cars have a slightly larger turbocharger than the previous generation which is more than capable of going beyond the limits of the map sensor (as well as the limit of safety for the engine and turbo itself) so make sure to keep an aware eye on the amount of pressure being achieved. The R and S3 have relocated the bypass valve to the intake side rather than on the turbo as seen on previous vehicles and the gti. As a result there is a long recirculation tube running under the intake to connect the bypass valve back to the inlet side. It was also found that power levels in excess of ~390 ft-lbs could cause early clutch failure, and going much over ~350 ft-lbs could result in some check engine lights under various conditions. If you start to notice slipping turn things down.

Pre-Tuning Checklist

Identify configuration of the vehicle.

The first step in tuning is choosing a COBB Tuning Off-The-Shelf (OTS) calibration that most closely matches the mechanical components, modifications, and fuel octane the user intends to use on the vehicle to be tuned.  To get the best idea, check our current map notes for physical part and fuel octane compatibility. Starting with these maps gives you a faster starting point if the modifications are similar. It’s also a good idea to double-check the mechanical condition of the car and make sure the mods utilised make sense for what the customer is after.

Preventing Issues When Flashing

• While flashing the vehicle it's important that the radio doesn't attempt to connect to your phone via Bluetooth as it can cause the flash to fail.

• Walking away with the key in your pocket, or having the key battery die while flashing will cause the vehicle to turn off while flashing.

• The car hood may need to be opened during flashing. This behavior is inconsistent but is advised when possible.

• Performing the initial installation of the Accessport must be done with a 10-20 amp battery charger connected to the car due to the long flash time for installation. Subsequent reflashes for new maps do not require a charger due to significantly faster reflashing.

• These vehicles do not like being flashed several times in succession without being driven on the street/dyno. In the event that the car doesn’t start immediately after finishing flashing it can be resolved by simply walking away for a few minutes with the key (to prevent the ecu and other functions from becoming active) and then starting it after your quick break.

When Running the Car on the Dyno

Make sure to disable all driver assists must disabled in the car. This includes traction control, lane-keep assist, and automatic emergency braking. These can be disabled in the center console.

The coolant and oil temperature gauge on the dash is a modelled measurement rather than current and can raise to "overheat" conditions after multiple gear, wide open throttle runs or a single 4th gear pull in higher ambient temperature days. For actual engine temperature it is recommended to log Coolant Temp on the Accessport or in Accesstuner.

Calibration Refinement

Perform initial testing at lower boost

After choosing the most appropriate starting point calibration, prepare to test and refine the calibration on a load-based chassis dynamometer. When creating a custom tune, it is best to begin testing under low load (boost) conditions by lowering values in the Maximum Intake Manifold Pressure Set Point. This lowers the requested load (boost). Testing done at lower boost will allow you to assess the calibration without putting the motor under potentially dangerous conditions. Start the tuning process by loading this "low boost" starting point calibration onto the vehicle. 

Tuning Strategy

The overall strategy used by the car to drive power changes functions in a straightforward manner:

Accel. Pedal → Driver TQ Demand → Mass Air Setpoint → Boost Target

There are multiple limiters at each step and care must be taken to ensure limits are not being pushed up against but also that they are not so far out of the way to disable any safeties.

Open

This Mk8 Golf R table contains no values aside from 0 when stock it is not functionally used stock

An important note to remember is that although many tables are present in the ATP software and within the ECU itself, they may not be active/referenced by the car when calculating targets/limits. Examples of this include tables that are not populated with any values that “make sense” (zeroed out) or multiplier tables that are set to “1” in every cell. It is possible that some of these tables are indeed active but effectively disabled through their calibration and may be changed with results on the dyno. In order to verify their operation, small but noticeable changes can be made, allowing you to safely make use of them.

Open

This table acts as an RPM based torque limiter but is clearly just moved out of the way stock

Torque

Within the Torque Folder of ATP are two types of tables requiring adjustment. The first is Torque Demand tables. These include the Driver Clutch Torque Demand and Torque Demand From Accelerator Pedal tables. These tables can be raised to set torque targets to near what the car is actually capable of, but you will want to keep the overall shape the same in order to preserve the stock feel of the power delivery. The shape can be altered to customize this feel somewhat but limitations such as turbo spool still exist. A good strategy is to raise these values fairly high and then taper down until the changes begin to drive a decrease in power output.

Limiters will also need to be raised in order to allow for higher torque targeting and output. These tables include 1D tables such as Maximum Torque Request as well as 2D, 3D, and 4D table sets allowing for limitations based on Gear, RPM, ambient air density, drive mode, and more. Again, it is advisable to raise these limiters out of the way during initial calibration and then lower them to acceptable levels before finishing. The 2D and 3D tables can be used to help define the shape of your power curve based on different variables and it is a good idea to leave these about 10% above the actual power output to act as an effective cap.

Load

After setting a torque target, the target is translated to an airflow target via the Mass Air Set Point for Torque Intervention tables by cross-referencing Requested Torque and Engine Speed. There are 24 tables with twelve each for high flaps and low flap positions for different intake manifold runner flaps. While the exact circumstances for the use of each individual table is not clearly defined, the ECU will interpolate between tables to set a final airflow target. Changes to one table should be approximately replicated for the remaining matching tables. These tables represent the torque-to-airflow model of the engine and changes should be made in such a way as to maintain the overall somewhat linear relationship. The resulting airflow is checked via the 24 Reference Indicated Torque tables to ensure proper airflow so any changes to the set point tables will need to be translated to these as well. You will also want to check the Limiters folder for the table Maximum Cylinder Air Set Point to make sure it is cleared for the necessary airflow.

In general, the lower airflow potential of a stock GTI may allow you to leave these tables unchanged. However, the table very evidently tops out at 1500 mg/stk at a fairly low torque target so these values may need to be extrapolated out to allow for greater airflow targeting. We recommend leaving the low airflow columns untouched in order to preserve low-end driveability.

Graphical comparison of the table changes above, the table on the right demonstrates a more linear progression of airflow values beyond 1500.

Wastegate Control

After an airflow target is determined based on the driver’s demand, the ECU will work to determine how much boost pressure is necessary in order to achieve the target airflow. While the final target is not directly controllable aside from limiting it, you do have a variety of tables available to allow you to control how accurately and quickly the target may be achieved and maintained. The wide variety of tables within this folder make calibration for replacement turbochargers fairly straightforward. Limits can be set and turbos modeled properly for small or large turbochargers. These tables are found within the Turbo Modeling and general Wastegate Control folders. For tuning a stock turbocharger setup, most tables can remain unchanged.

The primary wastegate control tables exist within the Wastegate Control Tables > Boost Target Tables folder.  Most critical are the Maximum Intake Manifold Pressure Set Point and Manifold Pressure Set Point Limit tables. These tables effectively act as a boost limit and a good calibration strategy is to begin with them set low and then gradually increase them until power goals are met or other limitations found. This folder also contains a variety of pressure related tables that act as limiters in other manners such as maximum pressure ratio and overpressure/underpressure diagnosis. When editing tables and limits make sure to update the Maximum Boost Pressure Display to allow for the dash display to show an accurate boost reading.

Boost Control is achieved through use of an electronic wastegate on the turbocharger and the input is run through a PID (proportional, integral, derivative) feedback system. This allows for very precise control of boost pressure in a closed loop manner. Tuning a PID feedback system typically requires only small adjustments under specific conditions where change is needed. The tables are set up in a 4D arrangement with adjustments available at different RPM points. We recommend thorough research into these systems and how to go about calibrating them before changes are made.

Finally, the Turbo Protection folder allows for additional limitations to be placed on turbocharger operation based on physical factors such as rotation speed and temperature. Some limits may be raised slightly but should be within the operational limits of the turbocharger being used.

Fuel

The Mk8 GTI and Golf R are fitted with high-pressure direct injection (HPDI) systems. In direct injection the gasoline injected directly into the combustion chamber of each cylinder, as opposed to conventional port fuel injection that happens in the intake plenum or cylinder port. This gives the Volkswagen 2.0T many advantages for improved fuel efficiency under light load conditions and also allows a leaner Air/Fuel ratio. Gains are achieved by the precise control over the amount of fuel and injection timings that are varied according to the load condition.

For direct AFR target control, the Basic AFR Set Point HPDI Single Injection and Basic AFR Set Point HPDI Multiple Injection will be the primary control points. The HPDI system is capable of delivering two discrete fuel pulses. Using multiple pulses allows for improved emissions and heat management. This system is managed automatically.

The ideal air to fuel ratio depends upon fuel quality. Higher octane fuels are more detonation resistant and therefore can be run at leaner air to fuel ratios. Leaner Air to Fuel ratios produce higher power but also create more heat. Excessive heat can lead to detonation. Lower octane fuels such as 91 octane or 95 RON are more prone to detonation and therefore require a richer air to fuel ratio. Rich air to fuel ratio combustion produces less heat and therefore less detonation. The GTI is set up to run 87 or premium from the factory and is fairly good at reacting to limit knock and optimize power.

There are many tables that allow for complete control of the fuel system including LPFP, HPFP, stoich point, and cranking behavior. They shouldn’t need much adjustment unless you’re needing to account for major changes in fuel stoichiometry or volumetric efficiency (running e85, built motor etc.) These tables operate as a factor/correction change to the stock fuel volume and can thus be modified according to the change in fuel mass necessary.

The Fuel Pressure tables allow for rail setpoints to be controlled. When using alternative fuels or high boost builds, fuel pressure at the rail will generally need to be increased to drive higher fuel volume delivery. However, a high rail pressure set point may only be achievable if the supply system is beefed up. Fuel pump controls allow for tuning an upgraded cam-driven HPFP for increased rail pressure and LPFP which will ensure the high pressure side is well fed. It’s important to be aware that observed dips in fuel pressure are often caused by low pressure supply deficits rather than high pressure side. HPFP calibrations are typically used for characterization of the mechanical parts used while LPFP calibrations ensure that the entire system is well fed. The feed forward tables will drive higher pressure but if greater than 95 psi is needed, we recommend upgrading the LPFP entirely.

Ignition Timing

Ignition timing calibration is a fairly straightforward approach. Ignition Timing Open Intake Flap Tables and Ignition Timing Open Intake Flap Tables folders contain the tables for the primary ignition timing targets. There are also tables for the minimum ignition timing which can be run in suboptimal conditions, ignition timing corrections for different combustion modes or conditions, impulse combustion, and knock control. The Ignition Angle Correction Combustion Mode 0-7 will be applied to the final ignition calculation depending on the current combustion state. This state can be monitored by selecting the Combustion Mode monitor and logging its output. 

Ignition timing is also adjusted in response to detonation or pre-ignition. The ECU actively reduces timing in response to detonation. The ECU has the capability to make individual cylinder timing adjustments, because of this monitoring a single cylinder’s timing correction will not result in a global picture of engine operations. Timing adjustments in response to detonation are logged with the Knock Retard 1-4. monitors. Generally speaking, higher ignition timing supports higher torque and greater power. However, ignition timing should be increased with great caution. Higher timing yields higher cylinder pressures and this is limited by fuel quality and the mechanical limitations of the engine. Too much timing will produce knock correction when fuel quality is limiting. When fuel quality is high, ignition timing should ONLY be added when its addition produces a substantive increase in torque and power. If increased timing does not increase torque the extra cylinder pressure is simply producing unnecessary stress on engine components.

Ignition efficiency tables will reduce/optimize ignition timing to hit your torque targets.

Knock Control

Ignition timing is a very critical component towards making power in the Mk8 platform. A simple change of 3 degrees in some places can easily translate to 20 ft. lbs. of torque gained. This also means that timing pulled is an effective way to control power in less-than-ideal situations. Per cylinder knock adjustments are useful for minimizing knock but there are some global adjustments that can be made