This is a ask we get a million times a day. Since 2007 all Dodge Cummins 6.7, Ford Powerstroke 6.4, and Chevy Duramax 6.6 trucks come from the facility qualified with a particulate filter to meet tougher emissions standards. A diesel particulate filter (Dpf) is a gismo that traps the soot and unburnt fuel from diesel combustion. You may have noticed if you have one the 07+ diesel pickups that it never puts out any black smoke at all. The Dpf will capture 90% or better of all harmful diesel emissions. Once the Dpf has come to be "full" of soot, it will need to have a regeneration cycle in order to burn all the soot out. You may have noticed a light on your dash from time to time that alerts you that the Dpf is in "regen" or "cleaning filter."
Basically what is happening while this process is that the engine's computer has decided from the facts that it receives from the sensors installed in the exhaust that the Dpf has filled up past it's proper limit. The computer then opens the Egr (exhaust recirulation valve) introducing hot exhaust into the intake to help get get exhaust gas temps higher and also injects a small shot of fuel into the cylinders when the exhaust valves are open. The raised exhaust temps and the small estimate of fuel then burn out the particulate (soot) that the Dpf has collected since it's last regen. Once the computer gets readings from the sensors in the exhaust that the filter is flowing an proper limit again, it ends the regen cycle. The frequency of this cleaning cycle is separate from car to car depending on use, mileage, and machine condition.
Myths about the Dpf system:
1. The lines on the side of the exhaust are fuel lines that dump fuel directly into the filter and the other connections are glow or spark plugs that ignite the fuel to clean the filter.
Not at all. As I stated above, the fuel needed for cleaning the dpf is entered into the machine cylinders by route of the regular fuel injectors while the exhaust stroke of the engine. A small shot of fuel is pushed out with the rest of the exhaust gas. The metal lines everyone sees on the side of the Dpf filter are for a pressure sensor that is normally attached to the side of the transmission or frame. They have the long metal tubes on them to get the climatic characteristic of the exhaust they are measuring down before it reaches the sensor. Again, I don't care what the tech at the dealership says about those lines, if he says they are fuel lines (which I hear all the time), he is an idiot and you should remove your truck from there as speedily as possible. The other wires you see going to the exhaust before and after the Dpf filter are not spark or glow plugs. They are thermocouples that measure exhaust temperature. The computer uses exhaust climatic characteristic and pressure before, at, and after the dpf to measure how plugged the dpf is and when it's time to achieve a regen.
2. I can just remove the Dpf filter and put a piece of pipe in there.
Sorry, no. If you remove the Dpf filter and make no adjustments to the engine's computer, it will enter whether a limp mode or a constant state of regen. Plainly put, all the sensors and the dpf have to be in perfect working order when running the stock vehicle's programming or else your truck will go haywire and you will not be able to drive it.
Common problems with the Dpf system:
1. Poor Fuel cheaper - This is the estimate one complaint we get from customers who have trucks qualified with a Dpf. Most customers who traded in their pre-07 diesel pickups have been wholly unhappy with the lack of fuel mileage that used to enjoy. The median fuel cheaper we hear people description on the Dpf qualified trucks is normally 12-14 mpg. Many of these folks traded in trucks that did 18-22 mpg and are wholly disgusted.
2. Immoderate regens - Many of our customers who use their trucks for work complain about very frequent regens that kill their fuel mileage and performance. Many customers who work outdoors in the winter were used to leaving their old diesels run all day while they were on the job site. The Dpf qualified trucks don't deal with this very well. The cooler idling climatic characteristic of the exhaust gas will soot up the Dpf on an accelerated rate. It is not uncommon for these customers to be on their second or third filter convert because the truck went into constant limp mode. The normally dealership response is: "You can't let these new trucks idle." Which goes over pretty well with guys who are stuck at a job site five miles back in the woods all day and the climatic characteristic never gets above ten degrees.
3. High change cost - If any of you have had to pay for a Dpf change out of warranty, you probably had a heart assault when you got the bill. A change Dpf (which isn't available aftermarket yet) runs practically 00-00 for the just the filter alone. And hears the scary part. Dpf life is estimated between 120,000 and 150,000 miles. If you plan on keeping your new diesel pickup for a few hundred thousand miles better start a Dpf fund.
4. Restricts doing modifications - With the new diesel pickups, the potential for horsepower improvements is tremendous. We have taken all three brands of pickups to close to or over 500 rear wheel horsepower and 1000 ft/lbs of torque with just intake, exhaust, and programming modifications. Never has so much doing been so easy and affordable while still maintaining road manners. The only question is whatever past a small tow type tune will aggravate the particulate filter. Turning up the machine will furnish more soot which will plug the dpf sooner causing more regens. Many customers who run a 100 horsepower program description very poor fuel mileage and constant regens.
What can be done to increase Dpf life and limit regens?:
Since we are not allowed by law to remove the Dpf system, we are stuck with it if you want to comply with Federal emissions and keep your truck legal. Here are a few tips to help mileage and Dpf life:
1. Use the right fuel - It is really crucial and valuable to use ultra low sulphur fuel in any car qualified with a particulate filter. High amounts of sulfur in the fuel will plug the Dpf immediately. We get lots of questions from farmers about the red fuel. As far as we know you can't buy high sulfur fuel commercially anymore. We have a refinery practically ten minutes from the shop that refines diesel. Both fuels are exactly the same, their is just red dye added to the offroad fuel. It won't hurt whatever to run the low sulphur red fuel. The other ask we get asked is about additives. Our advice is to only run products that were made for diesel fuel. Power Service, K100, Standyne, and Flash Lube for example are brands that we see no problems running. Do Not add any sort of homemade fixes. Adding a quart of saw oil, atf, or whatever else probably isn't a good idea. It will burn dirty and may clog the dpf.
2. Use the proper machine oil - Make sure you are using an machine oil that is rated properly for your truck. Some machine oil gets burnt up in combustion no matter what. If you are running oil that is not formulated for a Dpf qualified vehicle, it will soot up the filter sooner.
3. Keep idling to a minimum - Plainly put, idling contributes to dpf problems. Period. keeping the rpm's elevated while will help. keeping idling to a minimum is best for these trucks.
4. Run it hard once in a while - Don't be afraid once in a while when going up a hill to matt the throttle for a few seconds. Running the truck hard and getting things nice and warm will help clear out soot deposits.
I want to remove the Dpf. What can I do and what will be the benefits?
First thing, it is really against the law to remove or disable any emissions gismo for any car that is going to be operated on the social highways. If you determine you want to remove emissions equipment for any reason, it is solely up to you and your mechanic to determine what is safe and legal for your application. I do not condone nor recommend removing the dpf or any other emissions device. All the examples I speak about below were tested off-road and the mileage tests were performed on our Superflow chassis dyno that simulate the load the truck has alone and when towing.
We have done some testing on all three brands of trucks to see what results could be achieved by removing the dpf filter system. There are many products available for off-road and competition use that will disable the dpf system. You have to run some sort of aftermarket gismo to disable the theory or there will be problems when you remove the Dpf. There are some options that will allow the dismissal of the Dpf without any horsepower growth and also some options that will add up to 250 horsepower along with removing the Dpf.
Here are the test trucks we have done controlled tests on our chassis dyno with:
Truck #1: 2007.5 Ford F-350 6.4 Powerstroke
Mods: S&B Cold Air Intake, Edge Race Evolution, Dpf Delete pipe (rest facility exhaust)
Stock Rwhp: 285
After Mods Rwhp: 471
Average Mileage stock: 11.8 mpg
Average Mileage mods: 17.4 mpg
Notes: Very basic delete package. Thorough mileage jumped 5.6 mpg on simulated highway driving. Horsepower levels range from 40Hp growth to 185 hp growth on the Edge Race Evolution. Stock air box would pull filter restriction gauge with clean facility filter on even lower levels. Air box upgrade a must for this package.
Truck #2: 2008 Dodge 3500 6.7 Cummins
Mods: Full 4" Dpf and Cat delete exhaust, Flo-Pro Dpf electronics package
Stock Rwhp: 294
Mod Rwhp: 311
Average Mileage Stock: 12.1 mpg
Average Mileage Mods: 18.9 mpg
Notes: We were really impressed with this package. The Flo-Pro electronics only disable the Dpf theory and add really no horsepower. The free flowing exhaust showed some horsepower gains. Mileage test was simulated highway driving with a truck weight of 8700lbs. Great mileage gain of 6.8 over stock. Uncostly delete container for off-road work trucks.
Truck #3: 2008 F-550 6.4 Powerstroke
Mods: Dpf delete into dual 5" exhaust, S&B Cold Air Intake, Power Hungry doing Gryphon programmer
Stock Rwhp: 268
Mod Rwhp: 447
Avg Hwy Mileage Stock: 9.2 mpg
Avg Hwy Mileage Mods: 17.3 mpg
Avg Tow mileage Stock: 6.4 mpg
Avg Tow mileage Mods: 14.2 mpg
Notes: This is a container that we put together to simulate the gains potential on one of the hard working trucks that tows alot. The horsepower growth was dramatic, but the mileage gains were tremendous. We simulated a truck weight of 11,500 lbs for the highway tests and a trailer weight of 12,000 lbs for the tow test. The highway mileage tests of the mods showed a 8.1 mpg gain while the towing test also showed an phenomenal 8 mpg gain.
Truck #4: 2009 Dodge 2500 Cummins 6.7
Mods: 5" straight Dpf/Cat delete exhaust, S&B Cold Air Intake, H&S Xrt programmer
Avg Hwy mileage stock:14.6 mpg
Avg Hwy mileage mods:21.2 mpg
Notes: We only did simulated hwy mileage tests on this truck. We just used the Xrt programmer to remove the Dpf functions from the computer and left the horsepower stock. The Xrt has horsepower growth levels of 60, 120, 175 horsepower. It will also shut the egr theory off as well.
Truck #5: 2008 Ford F-350 6.4 Powerstroke
Mods: 4" Dpf delete pipe, 5" Mbrp dpf back exhaust, S&B cold air intake, Innovative Diesel custom tuned Sct Livewire
Stock Rwhp:289
Mod Rwhp: 536
Stock Mpg: 11.6 mpg
Mod Mpg: 17.4 mpg
Notes: This truck was an animal! The custom tunes were some of the smoothest shifting of any of the options we have tried and the power was crazy. There was a 247 rear wheel horsepower growth over stock on the top level and the rear wheel torque was over 1000 ft/lbs! You would think there would be a serious drop in the mileage department, but we were surprised to see the truck gain nearly 6 mpg at even this horsepower level.
In conclusion, if you are seeing for some serious horsepower for the drag strip or the pulling track, these new coarse rail diesels make serious horsepower with very petite modification once the dpf is out of the way. Also, if you only operated your truck off-road there are some highly impressive fuel cheaper gains to be had by removing the dpf filter. It is really too bad that we couldn't run the trucks on social roads with the dpf removed. We truly would have incredibly distinguished trucks that get great mileage and have phenomenal road manners.
Thanks for reading,
John Anderson