Vehicle Platform & ECU Name DTC Troubleshooting Data Ver: 1 Date: 23/11/2022 Author: ERC Page 30 of 834 Copyright by TATA MOTORS Ltd. This document must not be used in any w ay, such as copying and redistributing to third parties, w ithout our consent Engine Terminologies and Abbreviations: What is Power latch? ECU enters sleep mode only after 15 to 20 seconds in key off. The process of switching off the ignition for the duration until the ECU cuts its communication and enters sleep mode is called power latch. Power latch is mandatory for the ECU to memorize the values learnt in the current driving cycle to its permanent memory storage. What is Limp Home? It is the Engine operating state where Engine idle speed will be raised & restricted to 1100 to 1200 rpm. Vehicle will operate in driven idle mode only. Vehicle drive modes will be disabled. What is T87? T87 is the ECU main power relay output connection which supplies 12V to the ECU and several other components such as Throttle, EGR, VGT, IMV, EVRV etc from the battery. ECU receives 12 V from T87 through ECU pin numbers B3, B5, B6 (vehicle pocket). What is MDP and SPC? MDP is the minimum pulse required for movement of the injector control valve. It is subjected to variation because of wear and tear of individual injectors. In order to reduce the effect of this variation on quantity of fuel injection, SPC is done. SPC is an Injector learning strategy which learns in smooth decelerations of the vehicle (foot off without breaking). During this deceleration time, the ECU schedules different rail pressure demands and learns the drift in each injector. What is VGT or EGR or Throttle learning? As each mechanical part has its own wear and tear during the life of the part, it is required to capture this wear in the software to mitigate the effects of it on engine operation. Especially for the sensitive parts such as VGT, EGR and Throttle which has significant impact on engine intake air control for minimum variation in its position. These actuators closed position feedback signal is continuously monitored by the ECU and it learns the deviation in a permanent memory at key off condition or when learning is triggered with a service tool based on the recommendations from the part supplier.
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