Vehicle Platform & ECU Name DTC Troubleshooting Data Ver: 1 Date: 23/11/2022 Author: ERC Page 31 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 What is DPF regeneration? In order to meet BS6 emission norms, the soot particles emitted by the engine in the exhaust must be treated properly before it is let out in the atmosphere. DPF is the exhaust after-treatment device used for trapping the soot particles in the exhaust. The ECU uses post fuel injection to rise the exhaust temperature and create an exotherm in DOC. Due to this exotherm the exhaust temperature further increases and burns the deposited soot inside DPF. This kind of regeneration happens in normal driving cycle (approx. 50 kmph & above) at every few distance intervals and keeps the DPF loaded within the threshold level of soot. What is LNT DeNOx? In order to meet the BS6 emission norms, the Oxides of nitrogen in the diesel engine exhaust must be properly treated before letting it out in the atmosphere. LNT – Lean NOx Trap is the after-treatment part which does this function of trapping the NOx in the engine out and converting it into nitrogen before letting it to atmosphere and this process is called as DeNOx. In order to convert the NOx to Nitrogen, the exhaust air fuel ratio must be maintained at an AFR less than stoichiometric AFR (Rich phase) for few seconds which is achieved by the precise control of ECU on after fuel injection and intake throttle. What is LNT DeSOx? Out of various chemical compositions in the exhaust gas of a diesel engine, oxides of sulphur have more affinity to the adsorbent inside the LNT than the oxides of nitrogen which in a long run deteriorates the NOx conversion efficiency of LNT. For this, a regeneration process called as DeSOx is performed to remove the sulphur from LNT. During DeSOx, LNT bed temperature is raised using post injections and while the exhaust temperature is high enough, intermittently the AFR is maintained less than stoichiometric AFR for few seconds. The lack of oxygen and the high temperature in exhaust causes the stored sulphur in LNT to lose its affinity and gets flushed in exhaust. Abbreviations MDP – Minimum Drive Pulse SPC – Speed Pilot Control SPCS – Speed Pilot Control Service LNT - Lean NOx Trap (Upper part of Exhaust after treatment system) DPF – Diesel Particulate Filter (Lower part of Exhaust after treatment system) AMF – Air Mass Flow AFR – Air to Fuel Ratio EGR – Exhaust Gas Regulation
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