Introduction

The EA888 Gen 3 (EA888.3) is a global engine suitable for MLB (Modularer Langsbaukasten/Longitudinal ) and MQB (Modularer Querbaukasten/Transverse) platforms, capable of meeting the latest emission and fuel economy targets in different markets

In the Europe, the new MQB EA888 Gen 3 engines were introduced to Volkswagen Golf, Skoda Octavia, Seat Leon and Audi A3/S3 vehicles.  These engines were partnered with a 6 speed manual or the DQ250 6 speed DSG gearbox.

The 6 Speed DSG transmission has two wet clutches bathed using concentric friction disks and clutch plates.  like other gearboxes once clutch is drives odd gear, the other drives even gears.  Clutch clamping force is delivered by clutch pressure which in turn is which is converted to duty cycle and controlled by solenoid current.

Clutch pressure is controlled in full time closed loop, while clutch pressure targets are set primarily by torque Actual value sent from the ECM.  The DQ250 transmissions are known to hold slightly less torque that the later DQ381 7 speed gearboxes and in stock form the torque is limited by the controller to around 350-380Nm via calibrations. The physical limits of the transmission are not fully known but the clutch patch appear to slip before the gearset breaks. Advice from COBB is that during development it was found that measured torque levels in excess of 520Nm. could cause early clutch failure. If clutch slippage is noticed/logged it's recommend to reflash the ECM to lower the power output to avoid damage.

Tuning the transmission to increase the clutch pressures and delimit the ECM tune is highly recommended for any calibration. For higher power builds it will be essential to achieving the requested power from the ECM.

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The DQ250 has different drive modes, the main 3 modes are Drive (normal), Sport, and Tiptronic (TT). Depending on the vehicle configuration, there may be additional modes available, such as ECO (Economy), and ALT (High Altitude).

• Drive and Sport modes are the main influence on current gear choice. In these modes the DSG will choose the correct gear based upon

  • Torque Actual

  • Throttle position

  • Engine Speed

  • Driving Sportivity Factors

• Tiptronic Function (manual shifting) - Is selected using the factory paddles or by placing the shifter in the manual shifting (Tiptronic) position.  Within each of these drive modes there are more tables and logic to further define their function.

Programming and RaceROM

For information on how to program as well as flash recovery, check out.

NOTE: With all of the VW AG DSG’s gearbox adaptations must be completed after programming or it will not learn the new parameters to achieve clutch and line Pressures desired.

• ECU Programming Overview

• How to Recover an ECU
  
  

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For more software guides check out:

• Software Help and How-To

Clutch Learning and Adaption

After programming the TCM you need to reset the clutch adaptions on the DSG to make use of the increased setpoints and relearn the positions and duty’s for solenoids when different torque and pressure setpoints are used.

to complete DSG learning in ProECU simple open the DSG tools menu and reset the adaptions required.

Torque

The most important parameter for the DSG is the Input Torque which is received over CAN from the ECM. You must have accurate torque estimation in the torque to air and air to torque maps in the ECM, see the ECM tuning guide on how to set these maps up (VW AG EA888 Engine Tuning | VWAGEA888EngineTuning AirflowDetermination).

There are several important functions that compensate torque as it is recieved in the TCM, it is then also limited and a torque request sent back to the ECM. If the torque limits in the TCM are not increased it will apply a torque limit to the ECM and reduce the power, hence why tuning VW AG platforms ECM and TCM tuning should always be performed together.

Torque for Clutch pressure

Torque Control in the TCM is used for Torque limitation and Torque for target clutch pressure. The target torque and to Clutch pressure appears to be set using a linear conversion calculation from 0 to maximum torque matched converted and matched from 0 to maximum Solenoid Current. this is why it is important to have the TCM delimited and the ECM set to deliver an accurate amount of torque over CAN.

Ramp Rate’s for Pressure during shifts are based on Macro and Micro slip controllers that appear to drive clutch current up and down depending on their specific requirements.

Clutch Target Torque Correction Clutch 1 & 2

This map appears to offset the input torque for each clutch, in the example ROM this is increase to try increase the demanded clutch pressure.

Maximum Torque Clutch 1 & 2

this is the maximum possible torque the clutch can see, this map is number size 655, custom code will need to be implemented to exceed this value.

Max. Tq for Gearbox Protection

This value restricts the torque input into the gearbox for pressure calculations, its also possible that it is the limit for the torque reduction sent back to the ECM. this is normally raised to a maximum value to allow the ECM calculate the correct torque values.

Max. Temp for Gearbox Protection

This value also restricts the torque input into the gearbox for pressure calculations. Its also possible that it is the limit for the torque reduction sent back to the ECM. this is normally raised to a maximum value to allow the ECM calculate the correct torque values.

Adaptions and Clutch Torque to Pressure Calculation

From testing we have found that the clutch pressure attained is heavily related to the initial clutch adaptions made post TCM programming. It was found that if you program the TCM you MUST do redo the adaptions post programming otherwise full clutch pressure will not be achieved and kiss points will not be suitable.

Clutch adaptions slip monitoring are performed in closed loop an it appears to adjust the solenoid current and hence clutch pressure based on micro and macro slip values. Some of these are believed to occur during initial learning and others are made while driving.

While process has not been fully disassembled and understood adjusting the micro and macro slip adjustment current limits is regularly done to assist in achieving clutch pressures. See the example ROM for some possible changes.

Main (Supply or Line) Pressure

Main line pressure needs to be set to above the desired clutch pressures to ensure that there is enough headroom to deliver the clutch pressures from the main circuits. Line pressure uses a target and closed loop PID control strategy to maintain the desired line pressure.

Line Pressure Setpoint (torque)

The first step to increase line pressure is to increase the target. the target uses the torque input from the ECM to set the target pressure.

the Maximum Line Pressure needs to be raised

the Line Pressure Solenoid Current also needs to be rescaled to allow higher clutch targets to be realised.

There are many other maps involved in the closed loop control of line pressure but these should not normally need adjustment. More detail will be added here if tuning demands more information.

Shift Control

The DQ250 has many different shift modes and shift settings, the primrary Shift control functions are

• Shift schedules

• Forced Upshift and downshifts

• Shift time targets

• Pressure crossovers & torque reductions

• Kick down

The primary running modes for the gearbox are Sports and drive mode, however tiptonic (TT), ECO and limps modes can also be found. As discussed previously it is generally accepted that for most cases the sports mode shifting and tiptronic setpoints are generally acceptable but the normal driving modes need adjustment.

Adjustments to shift schedules can be done in using a few different methods, some more indepth than other, in this example a simple accel pedal axis and shift RPM changes were made in Drive mode, very few changes were made to ECO and Sport schedules as there are deemed to be OK.

Shift Schedules

The EcuTek example ROM uses adjustments to the axis break points and then the shift RPM’s in sport based on driving feel and driving style. To use this method you can view the example ROM changes here (VW AG DQ250 Example ROM Description | Shift Schedules Adjustment ).

Alternatively COBB have a very good sheet on a different method to set up the shift schedules, you can read their Shift schedule documentation here.

Volkswagen MQB 6 Speed DSG Tuning Guide

You can see that these maps use accel pedal and torque demand to determine an RPM at which the shift should occur, When the engine speed exceeds this value a shift will occur (provided none of the limits intervene).

If you wish to increase the RPM at which the TCM decides to shift at certain amounts of pedal increase the RPM point in these maps (for the mode you are trying to adjust for).

Forced Shifts

The TCM is set up to force up and down shifts at set RPM points in order to prevent overrev and excessive time on the rev limit. To disable this the Forced upshift to allow the driver to stay on the rev limit there are two settings for release of forced upshift strategy.

Release of forced Upshift in D & D (Offroad)

If you wish to keep the forced upshift but increased the forced upshift RPM to match your raised ECM rev limit you can changed the Forced Upshift maps for each mode. there are forced upshift maps for each gear and mode (Normal 1^st-6^th , Drive 1^st-6^th, Sport 1^st-6^th, TipTronic 1^st-6^th)

These Forced Upshift RPM Gear # → Gear # maps use Input torque to set a forced upshift rpm which you can raise to match whatever

Some of these maps are number size limited, if this is the case without custom code you will likely have to disable the strategy as opposed to adjust the maps.

Forced Downshift RPM can also be adjusted to prevent early downshift when in Manual / sports modes

Forced Downshift RPM use Input torque to set a forced down shift rpm which you can raise or lower to match your desired driving feel.

Forced downshifts are different to kickdown which are discussed in the following section

Kick Down

There are a series of flags and an accel pedal threshold to enable kickdown from various modes. these maps are a 0 or 1 value (1 = active 0 = disabled) and can be set for your driving requirements, in the EcuTek example the kickdown switch is disabled full time

Min Accel Pedal for Kickdown

this value is increased in the EcuTek example ROM to 110% disabling the function entirely.

the Flags for the Kickdown switch (Drive/Sport/Tipronic) are also set to 0 in the Example ROM

Shift times

The DSG shift from our (basic) understanding uses a shift time for the initial targets for torque ramp rates at the clutches and for torque reduction amounts in the ECM.

There are maps that control the amount of torque that is ramped in during and after the shift. These maps are split into at least two subsections one for global clutch ramp rates and also specific gear shift related pressure to torque rates.

the clutch torque rise limits are a 3D map with accel pedal and line pressure inputs to set a ramp rate but from the factory are set quite high so likely don’t need adjusting

the Pressure factors for the individual shift sequence's are 1D values that are multipliers of torque based on clutch pressure

The DSG uses a set of shift time maps for various running modes that use accel pedal and upshift type (i.e 1^st->2^nd or 4^th->5^th) to determine the initial target torque reduction and clutch switchover times

From our understanding this time target is used to set the torque and hence pressure targets for the clutch overlap times, the gearbox must also have sufficient line pressure, torque reduction amounts and torque ramp rates to enable this shift otherwise shift time will be extended.

Gear shifts also have a separate absolute and overlap torque limits that is applied during the shift sequence, these can be adjusted using the Maximum Overlap Torque gradients for incoming and outgoing clutches.

Maximum Overlap Torque limits the amount of torque that can bee seen in the torque overlap timer phase of the shift.

Max torque for Upshifts in the different modes can also be tuned to allow for higher torque shifts.

Clutch Current Control

There are several limits to clutch current control

The most important part of the clutch pressure control is ensuring that the solenoid current limits have been raised, we have not experimented to find the maximum safe current limit but to achieve the 16-18bar pressure a value of around 2000mA seems adequate.

Solenoid 1 Maximum Current for Max Torque

this allows the adaptions to allocate the larger target a higher current amount. the maximum duty also needs to be raised

Max. Duty cycle of Solenoid Valves

In our example ROM a duty of 75% seems to allow the correct clutch pressure and amperage.

Clutch #1&2 Current Offsets are believed to manually offset the calculated current target by a set amount based on the torque and gearbox temperature. In the example ROM these have been calibrated to give a little bit extra current at higher torque to ensure that the target pressure is actually achieved.

the TCM also performs closed loop current control to ensure that the desired target current is achieved, it does this using Proportional & Integral corrections for the controller.

These maps use a fixed value based on transmission fluid temperature and don’t normally need adjusting.

P & I gain Clutch 1 & 2 Pressure valve

Leakage control is the believed to be the running total of applied pressure to actual pressure which forms the basis of an offset current applied to the initial clutch current closed loop control and this function has its own separate closed loop system. The leakage control Int. current clutch 1 & 2 are used as factors to improve the pressure loss control characteristics of the clutch and are not normally adjusted.

Clutch Stall Speeds

The VW AG gearboxes use clutch stall speeds to determine the point at which the clutches engage when driving off from a standstill. the RPM at which the cutches are fully engages is called the Stall Speed. to achieve the stall speed the kiss points need to be learned, the kiss points are the point at which the clutches start to transfer torque from the input shaft to the output shaft and are learnt when doing the gearbox adaption sequences. The point of take-off also has limitations for torque, pressure and current.

The stall speed maps are the first port of call for adjustments, the stall speed maps are set for each mode (Normal/Drive, ECO and sport) for select gears as well as tiptronic specific stall speeds for the same gear sets as the

The stall speeds for higher temperatures (T0-2) are the 2D maps and each function has 3 different Gearbox fluid temperature ranges but generally

• T0->T1 is 135degC,

• T1->T2 is 145degC.

(Note: Clutch Stall Speed (T0/1/2) = “Drive” mode). In our example ROM we have lowered these to make the clutches grip properly from slow rolling starts.

The Neutral (0) to 2^nd and the 3^rd-6^th gear maps for each modes use the 3D maps (Note: first column is lowest gear last column ins highest gear) an have accel pedal and gear position axis to deliver the target stall speed.

Launch Control (DSG)

VW AG has kindly added a Launch control function (or Racing Start) to the DSG controller. Launch control is a function that has a separate stall speed, torque limit and sends a command to the ECM to use the Launch control Boost target and over boost torque increase function.

To enable LC in the car you will need to have the gearbox up to temperature and manual mode enable with sitting stationary with ESP off and steering straight. From there

1. Depress the Brake

2. Press the Accel Pedal 100%

   1. At this point the engine speed should rise and hold at the tuners setpoint (stock is 3200RPM)

3. when ready to Launch release the Brake

   1. at this point the car will drive away at speed.

there are many video’s available which describe how to initiate Launch control (examples such as https://youtu.be/T76oIxovSYw).

The temperature and brakes pressures to enable Launch control can be set up to better suit the driver making it easier or harder to enter LC mode. this can be done using the following maps

Brake Pedal Pressure to Enable LC

Minimum Temp to enable LC

there are also flags that can be configured for your specific preferences these are activation switches

To set the LC function to stay active with the ESP switch on set the Exit LC during ESP Activation map from 0 to 1

To enable Launch in specific gearbox Drive, Sport, Tiptronic or when the Active Slip Regulation is active modes set the checkboxes as required

Launch Control will deactivate if used for too long, this LC run time can be adjusted using the Max preloading time during LC map.

Once you have the activation settings for Launch control configured correctly you will then want to control happens when its in the old patter and what happens after the brake is released and launch is commenced.

This Launch hold function can be tuned in the TCM with Launch control stall speed setpoints (the RPM at which the gearbox sets as a hold point) being set using the Stall Speed (Launch Control) & Stall Speed ESP (Launch Control) maps these can be adjusted to match the desired launch RPM. You can also use the the ECM rev limits etc to make further adjustments once the LC limit is active.

There is also a Maximum Engine Speed Deviation During LC that when exceeded the LC function stop operating .

Once the Brake is released the TCM moves into post launch running after the Time for Brake release for LC timer has expired

and a post launch torque limit is applied using the Maximum Torque (Launch Control) map

This map can be used to limit the torque at launch, however you can also apply further torque limits in the ECM.

Miscellaneous maps and other useful Calibratable values

There are several setting in the TCM that have useful outputs that can improve the tune as a whole. these are calibratable values such as.

Instrument cluster Shift point display

You can change when the gearbox decides to send a shift notification to the instrument cluster. This is done using the CAN Sw. for Broadcasting Gear in Instrument cluster map.

where the switch determines when the gear recommendation should be output via CAN to the cluster, the settings are

0 =always
1 = active mode only
2 = only with target speed > 0

Pressure Sensor limits

the closed loop system for clutch pressure control requires a pressure sensor which is a 0-5 V sensor and if clutch pressure are pushed high the voltage value for the pressure sensor monitoring functions may be exceed. i this case either a lower pressure target needs to be set or the miinitoring function variable could be adjusted.

the Pressure Sensor Output Voltage Max map is default set to 4900mV.

Closing comments

While we have endeavoured to cover enough in this tuning guide to make tuning easier our understanding is based on limited testing and reverse engineering so if discrepancies or differences are found please contact support@ecutek.com and discuss the issues.