Join Date: Dec 2008
Location: Tyler, TX
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All 2007 emission compliant DIESELS for "on-road" use have "Diesel Particulate Filters" (DPFs for short). They also have a "Diesel Oxydation Catalyst" (DOC), but they have been around since the mid '90s in one form or another, and generally do not cause any trouble.
The DPF is basically a catalyzed filter. There is a coating on the core of the DPF (like a ceramic air filter - sort of) that helps burn the bigger chunks of soot into very fine ash particles, much like you "Webber Grill" takes a 50# bag of charcoal + some heat = cooked dinner + a small amount of ash. The DPF stores the soot until exhaust temps are high enough, then burns it to ash with the help of the "catalyzing agents", which are primarily Platinum and Palladium (rare and mega $$$ elemets).
What is "Regen". Regen is short for Regeneration, like a water softener would do. Basically, the engine controller can add more fuel, restrict inlet airflow, very the turbo output to CAUSE an increase in exhaust temperatures, which will in turn, burn the soot to ash.
There are THREE types of regeneration:
Passive: This occurs in any diesel fueled engine where EGTs are over apx. 600*F, basically while it is driven at highway speeds or under load. There is NOTHING "extra" happening, it is 100% natural.
Active: This is when the ECM does *something* to artificially increase EGTs so the soot can be burned to ash. This happens when the ECM sees the DPF becomming restricted with excess soot, and not enough EGT is present for passive regeneration. ACTIVE REGEN HURTS FUEL ECONOMY AND POWER. It is mostly due to light duty driving (grocery getting), and ideling.
Manual: This *may* be an option in some vehicles. The operator can initiate an "active" regeneration cycle while parked with the engine running. Again, this has negatives that go with it.
Why do some vehicles "regen" a lot more then others? There are three factors, you can truely only control 2 of them for now....
1) Oil. You MUST use "CJ-4" low ash oil in 2007 and newer diesel engine for highway use. Older CI-4 oils will poison the DPF.
2) Idle time. Extended idle time causes low combustion temperatures, excessive soot, and premature plugging of the DPF.
3) Fuel. All 2007 and newer highway diesel engine MUST USE ONLY "ULSD" - ULTRA Low Sulfur Diesel fuel. Unfortunately, MANY readily available fuels, despite having a sticker indicating "ULSD" are mixed with higher sulfur "LSD" fuels. This will DESTROY the DPF with extended use.
Sulfur in the oil and fuel will "poison" the DPF. Sorta like pouring water on your charcoal, then trying to get it to light. It'll never work.
Regeneration burns the soot to ash, therby reducing it's volume to approximately 1/1000th of that of the raw soot. Eventually, the DPF will need to be cleaned, but this is a 100,000 mile or later affair, with normal use.
'93 F-250 HD, 7.3L IDI, 5spd - FARM TRUCK
I Support: Trailer brakes an every axle over the towing vehicle's GVW; CDLs for RVers; Safety inspections for ALL vehicles and 6 axle trucks (97K GVW proposal).
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