The intake air valve acts as restrictor to reduce air entry into engine. Contribution to exhaust heat from late post injections is approximately 45%. Late post-injection pulses provide the engine with additional fuel which increases exhaust temperatures entering the DPF to 500☌ (932☏) and higher. Several engine components assist regeneration (engine speed, fuel pressure are adjusted). The computer can actually calculate how many grams of soot are in the filter based on info from all the sensors. The ECM will start a regeneration to clear this filter based on distance, fuel, and engine run time since last DPF regeneration, and exhaust differential pressure across the DPF. Excessive fuel useage, loss of power, and possible engine damage can result from too much back pressure caused by a clogged DPF. Calculations from this sensor are extremely important for DPF operation. There is also a Differential Pressure sensor with sample lines before and after the DPF. Self-regeneration will not fully complete soot-burning process if temperature is too low. Regeneration is terminated at temperatures above 800☌ (1472☏). The DPF substrate melts / cracks if temperature is too high. Proper exhaust gas temperatures at DPF inlet are crucial for proper operation and initiating regeneration. The ECM detects high or low sensor resistance voltage on signal circuit. As temperature increases, sensor resistance decreases. When EGT Sensor 1 is cold, resistance is high. The ECM supplies biased 5-volts to signal circuit and ground on low reference circuit to EGT Sensor 1. The ECM monitors signals from EGT sensors to control DPF regeneration. There are two EGT sensors, one before and one after the DPF. The soot that accumulates turns into residual ash after regeneration. It's channels are wash-coated with catalyst materials like those in DOC. It forces particulate-laden exhaust through porous cell which has silicon carbide substrate with honeycomb cell-type channels. The DPF (Diesel Particulate Filter) captures diesel exhaust gas particulates (soot) to prevent their release into the atmosphere. The DOC (Diesel Oxydation Catalyst) comes before the DPF and has been used on diesel engines for years. The DPF system has 2 components - the DOC and the DPF.

2008 duramax lmm dpf delete