Understanding ECU Remapping: The Audi TT 1.8 T - contiman - Free

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Understanding ECU Remapping: The Audi TT 1.8T Variants/Bosch Motronic ME7.x Figure 3.1. Overview of Bosch Motronic Torque-oriented Functional Structure Internal and external torque demands Priority Scheduler Cylinder Charge Path (long term) Priority Scheduler Crank Synchronous Path (short term) Actual Cylinder Charge (MAF) Conversion Target Torque to Target Cylinder Charge Calculations 1. Base Torque 2. Lambda efficiency 3. Ignition angle eff. 4. Reduction efficiency Conversion Target Torque to Target Crank Synchronous Variables 1 cycle takes 20 ms @ 6,000 rpm 120 ms @ 1,000 rpm 6 Conversion Target Cylinder Charge to Throttle Angle Conversion Target Cylinder Charge to Waste-gate Opening Throttle Angle Waste-gate Opening Individual Cylinder Fuel Cut-off Fuel Injection Timing Ignition Angle
Understanding ECU Remapping: The Audi TT 1.8T Variants/Bosch Motronic ME7.x The interdependencies between these variables are greatly simplified by introducing two central reference values: optimal ignition advance and optimal internal torque (which is achieved at the optimum ignition advance) when lambda = 1. Examples of internal torque demands are: starting, idling speed control, catalytic converter heating*, power limitation, components protection and engine governing. Examples of external torque demands are: driver inputs via accelerator pedal position, inputs from vehicle dynamic sensors and cruise control. *The 2.0 litre TFSI engine (described in SSP 337) has an interesting rapid catalytic converter heating mode known as dual injection with cold start. A quantity of fuel is injected on the intake stroke at approx 300° crank. The fuel distributes itself homogeneously due to the long gap before ignition. The second injection occurs at approx. 60° crank in the compression phase. The rich mixture that thereby forms around the spark plug means that timing can be retarded to a considerable degree without affecting stability of the engine. Both injection periods result in lambda 1. Since the exhaust valves are already open, the exhaust gas temperature rises rapidly. This brings the catalytic converter to operating temperature (350°C) in a short space of time (30-40 seconds). In addition to the Audi TT BAM and BFV ECU files referenced in the supporting information section, I have uploaded fully defined ECU files in WinOls .ols format for both the VAG 2.0 litre FSI and TFSI engines to the Definition Files section of the Nefmoto forum. Internal torque is converted to engine output torque by subtracting losses incurred in transferring the kinetic energy of the fuel/air combustion front to kinetic energy in the piston and overcoming friction and inertia in the piston/crankshaft system. Clutch torque is obtained by subtracting the torque required to drive auxiliary components such as the alternator, PAS pump and air conditioning. Wheel torque is obtained by subtracting frictional and inertial losses in the gearbox and differential from clutch torque. N.b. these losses are preset in the ECU by the manufacturer and are not evaluated dynamically. Target torque is calculated by looking up the optimal torque at lambda = 1 as a function of target cylinder charge and engine speed then reducing this by three scaling factors (lambda efficiency, ignition advance efficiency, and an individual cylinder fuel cut-off). Ignition advance efficiency is the difference between the actual ignition advance and the optimal ignition advance. 3.2. AFR Management There are three essential components to Motronic’s AFR management strategy, namely: (a) The basic calibration. The basic calibration target is lambda = 1 under all operating conditions and this component is designed to eliminate mixture variations caused by systematic errors. (b) Lambda pilot control Pilot control changes the target lambda value depending on the operating conditions, enriching the mixture for prompt catalyst heating to reduce emissions during start or warm-up, or running lean for fuel economy. (c) Lambda limits Limits are defined by the flammability of the mixture at a given engine load and are used to coordinate the AFR without the need to cross-reference calibration data. Although the stoichiometric ratio (lambda = 1) is the target, peak flame speed occurs around lambda = 0.9 and at this point, less overall ignition advance is required to achieve peak cylinder pressure. Adding more fuel or more air will slow down combustion. Flame speeds are in the region 18 to 25 m/s so in an engine with a bore of 81 mm like the 1.8T, the flame can travel from a central spark plug to the cylinder wall in only 1.6 to 2.3 ms. At an idle speed of 800 rpm, this equates to approximately 10 degrees of crank angle but increases to 62.5 degrees at 5,000 rpm. 3.3. Cylinder [Fuel] Cut-off Under certain conditions, fuel delivery is reduced or completely shut off, that is, the ECU reduces the injector pulse width, or does not send the injector activation signals. There are three situations in which this occurs. (a) Engine speed limit reached or exceeded. (b) MAP reaches or exceeds the prescribed value (overboost protection). (c) Deceleration. 7
Page 1 and 2: Understanding ECU Remapping: The Au
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Page 35 and 36: Figure 5.2. Flow Chart Summarizing
Page 43 and 44: Appendix 1. Functional Overview: MS
Page 45 and 46: Appendix 2. Functional Overview: Mo
Page 47: Appendix 3. Functional Overview: MD

Understanding ECU Remapping: The Audi TT 1.8 T - contiman - Free

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