"The" DPF removal write-up

[Boost]

I'd like to gather all the useful info in one place about DPF removal.

DISCLAIMER:

The DPF was designed to allow the Duramax to comply with the extremely strict new diesel emissions regulations.
Removing or modifying it is illegal in the US (even for offroad use)!

Now on to the good stuff:

For those that use their LMM for racing only and off-road, removing the DPF has shown substantial gains in fuel economy and power. However, it will cause serious complications. In this thread I hope to gather ALL of the correct information for people who decide to modify their LMM exhaust for whatever reason.

[Boost]

Some related threads for starters:

http://forum.efilive.com/showthread.php?t=6274
http://www.dieselplace.com/forum/sho...d.php?t=190052
http://www.dieselplace.com/forum/sho...d.php?t=185262
http://www.dieselplace.com/forum/sho...d.php?t=204680

[Boost]

These are the codes that are related to / set because of DPF removal:

P2459 - Regeneration too often
P244C - Catalyst temperature too low during regeneration
P244B - DPF differential pressure too high
P2463 - Diesel particulate filter soot level accumulation

[Boost]

Here is an overview of the DPF system:

The DPF system has 2 components - the DOC and the DPF. The DOC (Diesel Oxydation Catalyst) comes before the DPF and has been used on diesel engines for years. It's pretty much a regular cat. The DPF (Diesel Particulate Filter) captures diesel exhaust gas particulates (soot) to prevent their release into the atmosphere. It forces particulate-laden exhaust through porous cell which has silicon carbide substrate with honeycomb cell-type channels. It's channels are wash-coated with catalyst materials like those in DOC. The DPF is a "wall-flow" type filter. The soot that accumulates turns into residual ash after regeneration. There are two EGT sensors, one before and one after the DPF. The ECM monitors signals from EGT sensors to control DPF regeneration. The ECM supplies biased 5-volts to signal circuit and ground on low reference circuit to EGT Sensor 1. When EGT Sensor 1 is cold, resistance is high. As temperature increases, sensor resistance decreases. The ECM detects high or low sensor resistance voltage on signal circuit.
Proper exhaust gas temperatures at DPF inlet are crucial for proper operation and initiating regeneration. The DPF substrate melts / cracks if temperature is too high. Regeneration is terminated at temperatures above 800°C (1472°F). Self-regeneration will not fully complete soot-burning process if temperature is too low. There is also a Differential Pressure sensor with sample lines before and after the DPF. Calculations from this sensor are extremely important for DPF operation. Excessive fuel useage, loss of power, and possible engine damage can result from too much back pressure caused by a clogged DPF. 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. The computer can actually calculate how many grams of soot are in the filter based on info from all the sensors. Several engine components assist regeneration (engine speed, fuel pressure are adjusted). Late post-injection pulses provide the engine with additional fuel which increases exhaust temperatures entering the DPF to 500°C (932°F) and higher. Contribution to exhaust heat from late post injections is approximately 45%. The intake air valve acts as restrictor to reduce air entry into engine. Engine operating temperature increases by approximately 35%. The intake air heater can also help during regeneration. The turbocharger also plays role in achieving regeneration temperatures by reducing or increasing boost depending on engine load. It's contribution to increasing engine heat is about 10%. The are two main types of regeneration: Passive and Active. Passive regeneration may occur during normal vehicle operation when driving conditions produce sufficient load and exhaust temperatures, without input from ECM or driver (typically while vehicle is being driven at highway speed or towing a trailer). Active regeneration is commanded by ECM when the DPF requires excess soot build up to be removed and conditions for regeneration have been met. It's ususally hard to detect. The truck needs to be driven at speeds above 30 mph for approximately 20-30 minutes for a full regeneration to complete. During this time, exhaust gases reach temperatures above 550°C (1022°F). If regeneration is interrupted, it will continue where it left off (including the next drive cycle) when the conditions are met for regeneration. When regeneration is required, but the vehicle’s operating conditions do not meet the ECM’s requirements (such as frequent short trips or extended idling, the ECM turns on a “Clean Exhaust Filter” indicator. This message appears when the ECM determines soot levels are over 125%, and it remains on DIC display until after regeneration has been completed. Active regeneration has two stages. The first stage warms up DOC by reducing airflow using air intake valve, adjusting turbo boost and fuel rail presuure, and adding late fuel injection pulses. In the second stage the DPF is heated to temperature required to incinerate particulate matter. If a customer requested active regeneration is interrupted, the process ends and will not be activated again until conditions are suitable for regeneration or the regeneration switch is pressed again. An unknown amount of soot can be present resulting from engine or engine control errors caused by a charge air cooler leak, or low compression. If there is over 100 grams of soot, regen is not permitted. One trick is to unplug the sample lines of the differential sensor and force regen.

[Boost]

These are the parameters that have to be altered for DPF removal:

Change B2501 to No
Change B2502 to 0
Set the regen min engine temp to the max value (ie: higher than opperating temps)

[EFIGUY]

These are the parameters that have to be altered for DPF removal:

Change B2501 to No
Change B2502 to 0
Set the regen min engine temp to the max value (ie: higher than opperating temps)

Where do you set the regen min engine temp value? I didn't see that in the parameter section of the DPF?

[dustinparsons]

I don't see it either but have no problems just setting the regen to no. There may be some newer cal. files that helps show that. If so could some one let us know

[thetallengineer]

These are the parameters that have to be altered for DPF removal:

Change B2501 to No
Change B2502 to 0
Set the regen min engine temp to the max value (ie: higher than opperating temps)

Where is the min engine temp for regen located?

[Spuco]

These are the parameters that have to be altered for DPF removal:

Change B2501 to No
Change B2502 to 0
Set the regen min engine temp to the max value (ie: higher than opperating temps)

New to EFI Live, where are these peramiters found in the EFI?

[Dream2000]

New to EFI Live, where are these peramiters found in the EFI?

Change B2501 to No
Change B2502 to 0
Set the regen min engine temp to the max value (ie: higher than opperating temps)

Where is the "Set the regen min engine temp to the max value (ie: higher than operating temps)"

I don't find it either.