08-27-2009, 12:05 PM
Winnebago Owners Club
Workhorse Chassis Owner
Join Date: Jan 2000
Location: Conway, SC
Technical Report, Diesel Particulate Filters (DPF)
WORKHORSE TECHNICAL REPORT
Technical Report No. 1
from The Workhorse Technical Team
Motor home owners need to respond to
Note: These are a series of Workhorse Technical Reports with information that Workhorse considers most important in helping motor home owners avoid potential problems and maximize the economy, safety and enjoyment of their driving experience.
As new diesel emissions technology develops, motor home owners have new things to learn. There is one set of new warning lights for particulate buildup that it is especially important for those driving new diesel Class As to monitor — or risk damaging their engine.
Workhorse Custom Chassis, a leading manufacturer of chassis for Class A motor homes, has noticed instances of driver failure in this regard. Unfortunately, when this happens there is no warranty coverage for repairs and towing, not to mention the potential hazard to the driver and others. So it pays for drivers to read the manual and pay attention. They need to know what their gauges and warning lights mean.
All diesel engines produced after Jan. 1, 2007, must comply with the new regulations requiring the reduction of nitrogen oxide (NOx) and hydrocarbons (HC) by 50% and particulate matter (PM) by 90+% over the previous 2004 emission standards. To reduce particulate matter, a Diesel Particulate Filter (DPF) is used on all Class A diesel motor homes.
The DPF captures soot and larger sulfate particles in a series of ceramic honeycomb channels as gas passes through the porous material, and the particulates are trapped and accumulate on the channel walls. After thousands of miles, the DPF will eventually become clogged if nothing is done.
To prevent the DPF from clogging, the trapped particulates are burned off, and the filter is cleaned using a high temperature (around 1,700 degrees Fahrenheit in the Particulate Filter) regeneration process that leaves a harmless ash and residue. There are different regeneration processes for different diesel platforms, including automatic regeneration, manual regeneration, and DPF removal for an exchange or off-vehicle regeneration.
Workhorse’s new W16D, W20D and W22D chassis with MaxxForce™ diesel engines are examples of how both manual and automatic regeneration are used. The driver must monitor a series of instrument cluster system lamps that indicate various levels of low to full soot load with the DPF as determined by engine exhaust back pressure. For motor home owners who drive their rigs mostly at highway speeds, automatic regeneration will kick in. However, if much low speed driving occurs, manual regeneration may be needed.
For this typical system, there are four levels of warning indicators that signal potential hazards and the action needed:
First Level — Low soot load buildup: requires the driver to get up to highway speed to engage the automatic regeneration or to safely pull over and engage in manual Parked Regeneration.
Second Level — Exhaust filter is full: requires the driver to safely pull over and begin Parked Regeneration to prevent loss of power
Third Level — Exhaust filter is full and engine performance is limited: Driver needs to safely pull over and begin manual regeneration to prevent engine shutdown.
Fourth Level — Soot overload: a serious engine problem has occurred and the engine may shutdown soon. Safely pull off the road, turn on flashers, place warning devices and stop engine. DO NOT USE Parked Regeneration but call for service.
Manual Parked Regeneration is a simple process of hitting a switch that increases the engine speed to a set RPM that achieves the temperature needed to burn off the soot. Needless to say, this will make the exhaust very hot, so the driver needs to take care to park away from people or combustible materials and vapors. This process takes about 30 minutes. To thoroughly clean the DPF system, the motor home should also be run at highway speeds for 20 minutes after a manual regeneration.
As we mentioned, this soot buildup happens over thousands of miles, so the regeneration process does not happen very often to the typical motor home owner. However, if the warning lights do go on, it is very important that drivers know what to do if they want to avoid crippling their rig with serious engine damage.
new warning lights related to emissions control