2015 Mercedes G 63 AMG 5500 Twinturbo
Today we focus on a Mercedes-Benz G Class with a 5.5L 32v V8 Turbo petrol engine supporting a Bosch MED17.7.5.
The G Class is an off-road\SUV that has made history from 1979 and still nowadays is present in the market of new cars with the W463 series, a vehicle totally re-designed and inspired to its more “sporty sisters” like the Mercedes SLS. The design changed its off-road approach to a more sportive appeal, thanks to its set-up, the 7 gear G TRONIC automatic transmission and its four-wheel-drive system with possibility to activate or deactivate the differential.
The AMG version of the German off-road is available in two engines:
- 5.5L V8 BiTurbo petrol 544CV with automatic transmission
- 6.0L V12 BiTurbo petrol 612CV with automatic transmission
The model we are talking about can have 760Nm of torque from 2000 to 5000 rpm, while the max power of 544CV can be found at 5500 rpm.
The same engine is used also on some Mercedes luxury models like the S Class 63 AMG
Here are some features of the G Class:
Composition of the chassis: The G Class does not bend and not even breaks. Thanks to its solid base built with side members and cross members resistant to torsion and its composition made of steel plates of the thickness between the 3 and 4 mm, the chassis guarantees stability and perfect grip. The solid structure protects all the gears while facing rough situations. The chassis is powder coated, treated on the surfaces and then painted. All the holes are filled with warm wax, the body undergoes a KTL coating and the floor completely coated with synthetic materials.
Settings of the differential: G Class has three settings to block the differential that can be activated 100% separately: it’s the only system of assistance for the real off-road lovers.
Safety systems and comfort: Last generation ESP ensures better driving stability and safety. The ASR and the ABS improve the driving condition, reducing the distance to stop. This will allow a more fluid drive avoiding the risk of overturning during the bend.
ADAPTIVE BRAKE system: Thanks to some innovations for what concerns the software, it has been possible to add some new features to the ESP system for the hill start and the HOLD mode. To work at its best, the ADAPTIVE BRAKE uses also the information arriving from other security systems like, for example, the setting of the antilock braking system (ABS), the anti-slip regulation (ASR) and the brake assist (BAS). The HOLD feature is activated automatically when you press the brake pedal for a longer time after the vehicles has come to a complete stop, so to prevent the vehicle from unintentional motion without being forced to keep the foot on the brake pedal all the time. The support for the hill start will make the maneuver uphill easier, avoiding the risk of going backwards while switching from the brake pedal to the accelerator pedal. The system of course comes into action when the vehicle is on a certain percentage of slope.
AMG SPEEDSHIFT PLUS 7G-TRONIC automatic transmission: This particular kind of torque converter transmission is exclusively designed for the AMG products by Mercedes. It is also supported by a DIRECT SELECT at the steering wheel allowing the driver to switch among the three modes: "C" (Controlled Efficiency), "S" (Sport) and "M" (Manual), or even setting a cruise control. The double clutching system is automatic so to have a certain dynamism and safety.
Let’s take a closer look at the salient points of the electronic 4ETS four-wheel drive system
4ETS Electronic traction system: this system is controlled by the ECU that working in combination with ESP system and 4MATIC transmission and allows in a targeted manner to brake the wheels that tend to slide distributing the torque to the other driving wheels that still have traction.
This system is used in case of great speed differences between the wheels of the same axle and works almost like a limited slip differential. But the most important difference is that this system is applicable to the rear axle as well as to the front axle, so it has exactly the same behaviour of a limited slip differential but it works in an intelligent way, because the braking pulses sent from the 4ETS can vary according to the vehicle real time speed:
- If the vehicle is running at low speed, the braking is possible on all wheels, similarly to the locking of three differentials, in order to have the maximum traction/drive
- If the vehicle is travelling at normal speed, the braking force decrease in order not to compromise the driving stability
- If the vehicle is running at high speed, the system sets the brake pressure, on both rear wheels at the same time and doesn’t send any command to the front axle, in order not to vary the the security in terms of stability.
Mechanically, all this is made possible by a driveshaft located at the output of the gearbox that connect the torque converter. The torque converter is connected to two more driveshafts: one for each differential, in order to ensure that the torque is transferred to the wheels that have more traction, allowing to climb up to 80% uphill.
How to find and read the control unit?
With the K-TAG tool and the more common Tricore activation, family 692, plugin 714 we can create a backup of the ECU and modify all the engine parameters
Control unit details
Model: MED 17.7.5
Micro controller: Tricore IROM TC1793 GPT
EEprom: Inside the microprocessor
The ECU can be read with direct connection by using:
- 14P600KT02 cable
- MED GPT 14P600KT06 cable
- Soldering wires
To read/write the ECU there’s a simple procedure
- Solder the wire on the pin Boot as shown in the photo:
- - Connect the 14P600KT02 cable and the 14P600KT06 cable to the connector of the control unit following the scheme shown below
We will now analyse the driver main maps
The driver for this vehicle with 544CV V8 BiTurbo, that develops 760Nm, consist of 37 maps
They’re divided in:
- Air Control
- Injection System
- Engine Torque
- Spark Advance
Throttle Valve – operating angle
This map represents the opening of the throttle valve percentage, according to the airflow measured by the MAF and the volumetric efficiency. We can see that the maximum value doesn’t reach 100%, so we will have a limitation already given by this map. If expressed in %thr, the maximum will be 100% and it will be possible to linearize it with a 3D view.
Requested Engine Load
This map represents the ideal %Air which enter into the engine according to the RPM and the Torque requested from the Driver through the accelerator pedal; from zero up to 100% means that the turbocharger does not supply additional air, above this value means that the turbo works and compress the Air for the intake.
Engine load limiter
This map represents the maximum air percentage that can be supported by the engine, according to the RPM. As you can see there’s a limitation.
Components protection lambda
This map represents the calibration of a specific engine for the injection management when the vehicle works into protection mode, in order to protect the catalyst if the exhaust gas temperature is too high, according to the RPM and the percentage of air which enter into the engine.
This map represents the turbine compression rate based on the RPM and the atmospheric pressure; as you can see the compression rate is higher where the maximum torque increases, while it’s lower for low atmospheric pressure, as to protect the turbocharger.
Torque request in standard condition
This map represents the torque that the driver asks through the accelerator pedal based on the RPM and the %Acc (Driver wish). These are ideal values because they exceed the Nm real values that the vehicle can develop.
Optimal engine torque
This map represents the torque that has to follow a specific vehicle, according to the RPM and the %Air which enter into the engine; if the vehicle has a turbocharger, this map could be more than 100%.
Spark advance base map
This map represents the spark advance used into a normal state by the vehicle, according to the RPM and the engine load expressed in %Air, it gives the correct values in deg BTDC. It manages the spark advance according to a specific petrol into the tank.
Optimal spark advance
This map represents the maximum spark advance that the car can reach, that is the limiter of the maximum spark advance that a specific vehicle can reach in order to prevent any kind of damage; it is expressed in degrees before TDC and at low RPM and high values of the engine load they may find some negative values like delays.
This map represents the limitation expressed in RPM which the ECU uses in order to limit the maximum rotation of the engine.