FIAT’s two-cylinder SGE (Small Gasoline Engine) 900 cc Turbo with Multiair system is an example of this concept: it cuts fuel consumption and CO2 emissions, complying with the Euro 5 and 6 standards while maintaining a performance that equals bigger engines.

The VAG Group is investing in the downsizing concept as well, with the TFSI engine (Turbocharged Fuel Stratified Injection) and TSI engine (Turbocharged Stratified Injection). The latest engine is the 1.0L 3-cylinder TFSI, mounted on the cars of the VAG Group:

 

• Audi A1
• Audi A3
• Seat Ibiza
• Seat Leon
• Skoda Fabia
• Skoda Rapid
• Skoda Octavia
• Volkswagen Polo
• Volkswagen UP
• Volkswagen Golf

 

Let us start our analysis on one of these models: the 2015 Audi A1 1.0L 3-cylinder TFSI Ultra 95hp fitted with a Bosch MED17.5.21 control unit.

The 1.0L 3-cylinder TSI covers a power range from 82hp (for new drivers in Italy) to 115hp (e.g. VW Golf, Seat Leon, Audi A3, Skoda Octavia), including 95hp (e.g. Audi A1), 105hp (e.g. VW Up), and 110hp (e.g. VW Polo).

 

 

 

 

This car is available both with 5-speed manual and with 7-speed S-Tronic gearbox.

We will focus on the model with 5-speed manual gearbox

The car power reaches 70kW/95hp from 5000 to 5500 rpm and the torque of 160Nm is available from 1500 to 3500 rpm. Its inline 3-cylinder Otto engine has a GDI system, exhaust gas turbocharger and indirect intercooling. With its 102-97 g/km CO2 emission level, it complies with the EURO 6 standard and, thanks to its low weight, its fuel efficiency on mixed driving is higher than 22 km/l.

The engine uses the TFSI technology, i.e. Turbocharged Fuel Stratified Injection.

The engine technology of the Volkswagen Group refers to TSI, namely TFSI, to define the direct injection in turbo engines.

TFSI engines’ feature is the high performance of their torque on a wide range of levels. While previous generations of turbo engines had to face the typical features of the turbo technology, TFSI engines have a uniform acceleration trend, with virtually no delay of the turbo performance. The torque timing is highly advanced, as typical of diesel engines, and is maintained up to the highest regimes, typical of gasoline engines. This system allows a small engine to have high torque performance and output power.

TFSI powers are similar to diesel-driven generating sets. The injection process is set as in diesel engines. Both engines inject, under high pressure, in the combustion chamber. You can see and feel the analogy. When parked, TFSI engines offer the typical sound of diesel engines.

Here is an image of direct injection:

 

Since their launch in 2004, TFSI engines have been given several awards, among which the renowned “Engine of the Year” Award. There is no other engine with the same performance in the reference class. Besides, the small displacement and the high torque ensure a significant reduction in consumption in average regimes. The right gear train together with the engine create a dynamic car with low fuel consumptions.

TFSI engines adjust their consumption level according to the regime: a lower regime reduces fuel consumptions.

 

How to read and where to find the control unit?

Technical data of the control unit

Manufacturer: Bosch
Model: MED17.5.21
Microcontroller: Tricore IROM TC1782 TPROT
EEprom: Internal to the microprocessor

 

 

 

 

What do you need to read the control unit?

KESSv2 - 477
- Virtual Reading: YES
- Write: YES
- Cable: 144300KCAN

This protocol reads and writes the control unit. The original file is automatically downloaded through the K-Suite software (when the user saves the control unit ID on his/her computer): virtual reading.

K-TAG - Bootloader Tricore - PRT 689 - Plugin 695
- Read: YES
- Write: YES
- Checksum Correction: YES
- Direct Connection: 14P600KT02, Cavo MED GPT 14P600KT06

The boot pins are on the right side of the control unit. To connect the tool to the control unit you will need a 14P600KT02 cable and a MED GPT 14P600KT06 cable.

 

The Driver contains 31 maps

Focus on mapping

>> Desired lambda

 

It allows the engine to stop the closed loop function (when the injection is regulated to keep lambda =1), thus injecting more gasoline by high engine revolutions and load.

 

>> Components protection lambda

It allows a regulation of carburation such as to prevent damages of the catalytic converter and the knock sensor.

• Charted display

 

• 3D-Display

 

>> Throttle valve - operating angle

It allows regulation of the opening of the butterfly valve. The adjustment strategy applied levels the map (removing gaps) to avoid rush reactions of the engine using the 3D change of ECM.

 

•  Butterfly valve operating angle – original – charted display

 

 

• Butterfly valve operating angle – modified - 3D-display

 

>> Air flow through the butterfly valve

It allows scaling of the MAF measurements or, in case it is replaced, to re-adjust the ECU for the new measured values.

 

>> Rail pressure

This map controls the fuel pressure in the common rail to increase the efficiency of combustion through a better interpretation of the real values (bar) and to avoid inconveniences.

The values in the map (bar) show that high-pressure levels are achieved: 250 bar!

 

 

• 2D-display

 

>> Torque request during acceleration

It manages the torque demand of the driver when accelerating, shown in Nm.

 

A comparison between our Audi A1 (95hp) and a VW UP (105hp) is therefore very interesting to notice the differences in the torque demand maps.

As shown by the image, the VW UP (red eprom) shows average torque values 20% higher than the Audi A1 with 20hp less.

 

>> Maximum torque limiter

It shows the maximum torque of this engine, shown in torque %.

 

 

>> Advanced timing

We succeeded in implementing the maps managing both the advanced and the optimum timing. It is important to differentiate the two maps, since the optimum engine timing shows the maximum limit for changes, while the base map timing is the map used in the normal functioning of the car.

Optimum engine timing

The most meaningful values are by maximum engine load and revolutions, here they reach almost 24 degrees and are the highest level possible.

Base map timing

 

The most meaningful values are by maximum engine load and revolutions, like by the optimum engine timing (limiter), and are definitely lower.