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Diesel emission systems and the future!!! Part 2 – DPF

Hey guys back again for part 2. In part 1 we covered EGR systems which were introduced in order the “recycle” spent exhaust by cooling it and reintroducing it back into the intake mixed with fresh air. The EGR system lowers combustion temperatures and reduced NOX emissions. In 2007 more regulations were introduced that required vehicle manufacturers to reduce the amount of soot (particulates) in diesel emissions. This required a lot of planning for solutions since, soot “black smoke”, has been common in diesel engines since their inception because unburnt diesel fuel in large particles comes out in the form of soot. This mandate gave birth to the creation of the diesel particulate filter (DPF). A DPF is a filter that is installed in the exhaust pipe after the turbo and before the tailpipe. Inside a DPF is a collection of metals in a honeycomb core. This core traps soot particles in the exhaust to prevent them from leaving the tailpipe. This filter, not unlike other types of filters, will eventually become restricted with particles and will need to be cleaned out. The process by which the filter is normally cleaned is called “regeneration”. Early means of regeneration for Powerstroke, Cummins, and Duramax all involved “post-injection”. Post-injection involves firing the fuel injectors on the exhaust stroke in order to send hot unburnt fuel straight to the DPF in order to burn out the soot particles. This “post-injection” strategy was successful at burning out the soot but caused widespread issues as well. The engine sending fuel into the cylinders on the exhaust stroke caused fuel to get past the piston rings and causes “oil growth”. In many cases the engine oil level would become overfull and could cause a “run-away” condition or cause engine damage on the bottom end. Also this hot (1200-1300) exhaust has to go through the EGR system and turbo before reaching the DPF which causes additional wear on these components. These early DPF systems were laden with problems and caused many trips to the dealer for customers!! Now we will look at the big 3 individually.

2008 Powerstroke emission system-

In 2008 Ford introduced the 6.4l Powerstroke engine. The 6.4l had 2 huge goals hanging over it’s head: 1. Improve on the 6.0 2. Meet new EPA guidelines

The 6.4 Powerstroke is equipped with 2 EGR coolers (vertical, horizontal), 2 turbochargers, a new common-rail fuel system, an EGR valve, a DPF, an intake throttle, a diesel oxidation catalyst, and a converter. These emission components combine to clean up the NOX and particulate emissions to meet the 2007 guidelines. The 6.4 used “post-injection” to actively regenerate the DPF when it became restricted with soot material.

Below is a pic of a 6.4l cat/DPF assembly. Pic is not mine!


Problems: The 6.4 was plagued with problems in the emission system as well as the engine. The early DPF systems across the board tend to be the most unreliable years to own since the “post-injection” method was being used and SCR had not been introduced yet. The 6.4 suffered from ruptured EGR coolers, sticking EGR valves, defective exhaust temperature sensors, clogged DPFs, and oil growth. Oil growth is so bad on the 6.4l that it has been known to cause lack of lubrication because of fuel dilution which can cause damage to engine bearings as well as rocker arm pivots. The most pronounced downfall noticed by owners is just how low the fuel mileage is on the 6.4l. Because of the post-injection process fuel mileage on the 6.4 can be as low as 12 mpg unloaded and 7 mpg when towing. This is a huge decrease from previous engines and can be the most frustrating of all to a new diesel owner.

Fixes: The fixes for the 6.4l Powerstroke are very similar to the 6.0 fixes. There are “delete” options that are not street-legal but they do offer a solution to oil-growth and loss of longevity in the 6.4 Diesel. Unfortunately for owners, the emission solutions available involve fixing this DPF system which is a bad initial design in most peoples’ opinions. Aftermarket EGR coolers can be purchased for the 6.4l from Bulletproof diesel and these give you a lifetime warrranty as well as not altering your emission system in any way. The EGR valve however doesn’t really have an upgrade available but the 6.4 EGR valves are much more reliable than the valves on the 6.0. The DPF doesn’t really have an aftermarket as well that will cut down on any of the engine issues. The regen process is really the culprit here since the diesel fuel that seeps into the oil pan is normally what causes runaway conditions, worn rocker arms, and engine bearing failure. When the engine gets overfull the extra oil will make it’s way to the intercooler where it can build up and be sucked into the turbo causing engine damage. Unfortunately if you have a 6.4 diesel you will have to choose between deleting it for reliability or maintaining it religiously to ensure oil growth doesn’t get out of control.


2008 Duramax emission system-

In 2007.5 the LMM Duramax was introduced. The LMM has an EGR cooler and valve as well as a DPF. Like the 6.4 Powerstroke, it used (late or post-injection) to send raw fuel to the DPF to clean it out and burn out soot. This causes the same issues of oil growth and washed out cylinders that the 6.4 Powerstroke experienced.

Problems: The EGR cooler and EGR valve on the Duramax are high failure items and due to the post-injection method of regen this year model suffered a horrible loss of fuel economy from previous years. The DPFs in these year trucks would fail internally as well resulting in a loss of power and engine stall.

Fixes: The fixes for this year emission system are very similar to the 6.4 fixes. You’re either gonna end up deleting the emission systems and gaining 30% fuel economy or you will be replacing DPF and EGR components as they fail. I know this doesn’t sound very optimistic but to be honest these year engines don’t really hold value well since the previous years and later years get better mileage and reliability.


2008 Cummins emission system-

The 2008 Dodge trucks with the Cummins engine were introduced with a DPF, EGR cooler, DOC, and NAC (Nox absorption catalyst). The NAC stands out here since it is only used on the Cummins. It is essentially a precursor to the SCR catalyst that comes in later year engine. The NAC converts NOX to nitrogen and oxygen by capturing NOX in lean conditions and converting the gas during rich operations. This catalyst had to be regenerated as well to remove sulfur from the catalyst with a 3-5 second regen process that occurs every few minutes. The DPF also requires a regen when it gets full as well.

Problems: Very similar to Duramax and Powerstroke with even more of a loss of fuel economy. Due to the NAC needing to be cleaned the engine will burn more fuel in a shorter amount of time. Also the early regen strategies in the ECM were less than optimal and would sometimes require long drives to successfully clean out the DPF.

Fixes: The 6.7 2007.5-2012 is a great engine but is plagued with DPF related failures. Deleting the emission system is an option but if you want to keep the emission system a necessity is updating the ECM. The newer ECM strategies help with regen issues and can help reliability going forward.


Stay tuned for part 3 where we tackle SCR!!! Thanks for your time!






Diesel emission systems and the future!! Part 1 – EGR systems

Hey guys! It’s been over a year since I did an informative blog since we’ve been so busy at work but I’m back!! If you’ve purchased a new diesel since 2003 (Duramax 2004.5, Cummins 2007) then your engine is equipped with an emission control system. Today I’m gonna be looking at diesel emission systems in Powerstroke, Duramax, and Cummins engines but many if not most other manufacturers use very similar emission control systems. Emission control systems reduce emissions that exit the exhaust in order to prevent environmental damage from NOX, soot particulates, CO2, sulfur dioxide, and other emissions related to diesel fuel combustion. I do not claim to be a legal professional or an expert on governmental regulations but before 2003 the only state that had diesel emission regulations was California but for simplification let’s start looking at 2003 model year vehicles. The EPA passed regulations starting 2004 model year requiring diesel vehicles to reduce their emissions. There had been previous alterations to the diesel fuel itself to lower sulfur in order to cut down on sulfur dioxide emissions but the 2004 changes required making changes to the engine itself. The answer to these new regulations in 2003 for Ford/Navistar was an EGR cooler and valve in combination with an oxidation catalyst (a type of catalytic converter). An EGR cooler is a device that has coolant flowing through it and exhaust from the engine (before turbo) flowing through it. The coolant cools the exhaust to where it is cool enough to be mixed with fresh air from the turbo and reintroduced back through the intake. An “intake throttle” was also used in conjunction in order to cut off some of the fresh air so more of the exhaust can be introduced. This “recycles” a portion of the exhaust causing the emissions to be greatly reduced.

This is a picture of the EGR system flow.


This is a picture of the EGR system on a 6.0 Powerstroke engine.


Duramax engines also introduced EGR around the same time with early LB7s gettting EGR for California emissions but all Duramax engines received EGR systems beginning in 2005 with the LLY. The Duramax has the same style system with an EGR cooler and an EGR valve but the Duramax did not use a fresh air throttle assembly.

This is blown-up pic of an LLY system. Very similar to 6.0 Powerstroke but proven to be more reliable.


Common EGR failure points 2003-2007:

  1. EGR valve- Powerstroke and Duramax. EGR systems tend to be very dirty since soot from the engine is constantly flowing through the EGR cooler and when the valve opens this soot enters the intake manifold and will come into contact with oil residue from the crankcase ventilation system and create a black sludge that develops. This causes clogged sensors, clogged coolers, and eventually will cause the EGR valve to stick. When an EGR valve sticks it basically opens the floodgates for your exhaust which now flows straight into the engine and is no longer utilized to spool the turbo. This causes loss of boost pressure and LOTS of black smoke. EGR valve failures are VERY common in these and all EGR engines.
  2. EGR cooler- Powerstroke-common Duramax-uncommon. EGR cooler failures are very common in Powerstroke engines and are one of the 2 major causes of headgasket failures in 6.0 Powerstrokes. The Powerstroke system is unique in that the EGR cooler gets the coolant it needs from the oil cooler in the 6.0 engine. The problem with this is that the 6.0 oil cooler is very prone to getting clogged and causing the EGR cooler to be deprived of correct coolant flow. This causes the EGR cooler to overheat and rupture. When the EGR cooler ruptures coolant will flow into the exhaust and may damage the turbo. If the EGR cooler leak is very intense then coolant can flow up to the EGR valve and when the valve opens, coolant can flow into the intake causing a hydro-lock condition (which can damage engine/headgaskets). Blown EGR coolers on 6.0 Powerstrokes normally cause LOTS of white smoke and steam coming from the exhaust pipe. Duramax EGR cooler failures are pretty rare but can occur and will cause lots of white smoke and coolant loss as well.

Heres a pic of a 2004 6.0 Powerstroke with a blown EGR cooler. There was about a gallon of coolant in both exhaust manifolds!!


Fixes for common failures:

1. EGR valve. There are no upgrades to available EGR valves in the Duramax and Powerstroke. Ford does sell an EGR “shield” that installs below the EGR valve and helps prevent oil vapors from soaking the valve.

2. EGR cooler- There are multiple solutions for EGR cooler failures in both the Duramax and Powerstroke. The early 6.0 EGR coolers used large rows internally and are very rare to rupture. The 2004 and up coolers used a radiator row style design (see below pic) and are very common to fail around 100k miles. A common practice is to install an EGR delete kit which bypasses the cooler and valve and requires programming to the ECM to tell the engine to stop looking for these emission devices. The problem with this solution is that it is ILLEGAL. Bottom line. Another option is to replace the cooler with a cooler from These guys modify these coolers and beef them up and also throw in a LIFETIME warranty. Very good product and will last.

Below is a pic of a stock EGR cooler vs a Bulletproof diesel cooler. Pic property of Pawlik Automotive


You may be wondering how Cummins got by without an EGR system and the answer is…they didn’t. Cummins achieved their goals with “in-cylinder EGR”. Cummins changed the camshafts in 2004 to have a profile that would actually close the exhaust valve earlier than before and this would hold in exhaust longer causing an EGR effect. They also introduced a 3rd injection with the fuel system as well. They were no longer able to achieve this after the 2007 EPA regulations and thus EGR was introduced in 2008 with the 6.7l Cummins.


Thanks for reading guys stay tuned for Part 2!!


Bosch fuel system distributor- 441 Diesel

441 Diesel is proud to announce that we are now a Bosch diesel vehicle diagnostics (DVD) center. This means we can get you OEM fuel system components (injection pumps, injectors, filters, and other components) direct from Bosch for a much lower price than dealers (GM, Navistar, Cummins). Most of the time if you order Bosch products from a dealer chances are they are getting the parts from Bosch and marking them up again to then pass the higher price along to you. We cut out the middle man!! If you own a Duramax, Cummins, or Powerstroke (7.3l, 6.4l, and 6.7l) then you have Bosch brand products in your engine. Also countless other medium and heavy-duty engines! We take pride in our work and from our years of experience we have found that the best quality parts will ensure the best operation and durability. I have repaired countless diesel engines that were misfiring because of poor quality rebuilt fuel system components. We are proud to offer OEM Bosch products for your diesel! Call us today for pricing!





New shop!! Same great service!

Hey folks! It’s been way too long since I’ve put a new blog up on here. I just wanted to introduce all of our customers and followers to the New 441 Diesel!

This is the new customer waiting area. I love the decor and layout that my mom designed. We are looking for a display case to layout some diesel parts and performance products we offer. The waiting area is air conditioned and provides a comfortable place to wait while we take care of your truck.


Here is our new office with my mom Kim Orr hard at work on the computer. The exposed wiring design looks very good. This is where we do our invoicing and inputting bills.


Our new and very much improved entrance. Excuse the mess we are still finishing up construction and our builder still has a few t’s to cross and i’s to dot. The awning gives us more room as well as shade for when we have to work on trucks outside or if we want to do a quick AC check or PM. Loving the fresh vinyl on the billboard from Accel Advertising.


My favorite part! The shop has double the amount of space of the old shop and we now have 6 bay doors instead of 1. Huge improvement! We also have a cool workout area in the back. The 3 rear rooms are still works in progress. We will have a parts room and engine/trans build room where we can assemble engines in a sterile environment.


My brother Zach, basking in the glory of the new shop! LOL


I just want to take a moment to thank you if you are reading this. Without our customers we could not be here. At 441 Diesel, we strive everyday to do the best we can do. We treat our customers how we would want to be treated. We also communicate constantly with our customers and with each other in order to continually improve and be better technicians. 441 Diesel uses OEM and OEM quality parts for all repairs ensuring a quality fix the first time. Thank you all so much and God Bless. AJ


Detroit Diesel 60 Series Code 68. No cruise, no jakes

We do a lot of diagnosing at 441 Diesel but that’s not all we do. We do a lot of medium and heavy duty too. This particular truck is a 2005 Freightliner with a Detroit Diesel 60 series. The complaint was a consistent “check engine” light and no jake brake activation/no cruise. I checked it with the Detroit software and saw that the code was for an open circuit for the idle validation switch. The idle validation switch tells the ECM when the accelerator pedal is in the idle position. It is integrated into the accelerator pedal position switch which the previous shop had already replaced. The first thing I did was test the switch. The idle validation switch is just a 2 terminal switch that makes a circuit when the accelerator pedal is released and this completes the circuit sending a ground to the ECM indicating idle. After verifying the switch had 0 resistance when released and inf when pressed I knew the switch was good. The next step was testing the harness. I removed the connector at the ECM and checked continuity from ECM connector to IVS. The wire was definitely broken and showed infinite resistance. We removed the harness and took it apart.

After taking the harness apart we found this broken wire and 4 other wires that were eaten into. This part of the harness was at a sharp bend where a bracket held the harness. We decided to replace the entire vehicle harness because previous shops had done multiple repair to this harness and repinned the data link circuits. This repair shows where the disconnect is for many shops that do not understand wiring completely. If you have any electrical issues or have a truck that no one can fix leave it with 441 Diesel. Thanks guys


Duramax hole in transfer case

Hey guys this is AJ with 441 Diesel. I like to update this blog periodically to keep our customers and friends in the loop with common failures we see. We work on a lot of Duramaxs and a failure we run into a lot is a failure in the NP261XHD and NP263XHD transfer cases. The main issue we see in these cases is that a hole develops in the rear housing and leaks all the fluid out. Once all the fluid has ran out then we see a failure of the shift fork in most cases and this will cause it to drop out of gear going down the road or make a loud grinding noise. The cause of this failure is what we are gonna look at today.

The pump that supplies fluid to these transfer cases rides on the main shaft and the design flaw that causes the hole in the case is the clip pictured below. (courtesy of

This metal clip is designed the push against the pump to prevent the pump from contacting the housing. What happens in theory, as you can see below, is that the clip actually eats into the aluminum case and can wear a tiny hole in it.


The fix for this issue depends on the amount of damage done to the transfer case by the low fluid condition. In many cases the only damage will be to the shift fork. The fork in the picture here is the one that will be damaged in many cases. The plastic lining on the fork falls apart because of the heat and causes a lot of play in the fork area. This allows the collar to move and can cause the transfer case to drop into neutral.


The fix for the “pump rub” issue is a “pump rub repair kit”. These are available through Merchant Automotive online and provides a new design pump with long legs that sit against the housing and eliminate and rubbing issues. You MUST address any damaged components in the transfer case as well as replacing the rear half and installing this new pump. If you are having issues with your transfer case this may be your problem and 441 Diesel has your solution. Thank you for your time, AJ


6.0 Powerstroke Water-in-fuel light

If you own a 6.0 Powerstroke then you’ve probably had the water-in-fuel light come on and many people have learned to live with the light being on all the time. The problem with this is obviously you won’t know when you actually HAVE water in your fuel. Fuel injectors for the 6.0 are around $265 ea. so allowing water to damage them can cost you more than the fix we’re gonna go over today. The water-in-fuel (WIF) sensor on the 6.0 is located in the fuel pump on the driver’s side frame rail. The fuel filter separates the water and channels it down to the drain plug where it can be drained periodically. Unfortunately most people do not drain the water frequently enough so the water coagulates and creates a mucus-like substance that sticks to the sensor. The sensor can be seen in the pic in the lower left corner.

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Most of the time when customers bring this issue to us it is already beyond the point of just draining the housing. We repair this issue by removing the fuel pump from the vehicle. We then remove the filter and this cover that houses the sensor and fuel lines. The pan below is a good example of the amount of crud that normally comes out of a filter housing when the WIF light has been on for an extended amount of time.


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The pic below is the filter housing with the filter removed. After removing the fuel pump cover (manifold) you can flush these contaminants out with some cleaner and maintain a clean housing.

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After removing these components we flush the housing out with cleaner and install a new manifold gasket, fuel filter, and WIF sensor. This ensures a long-lasting repair that will allow you to keep an eye on your fuel quality and make sure to keep your injectors healthy. Thanks guys.


2006 6.0 P2614 P2617 No start

The 6.0 Powerstroke has a tendency to develop electrical issues as it gets more miles on it. The engine wiring harness on the 6.0 has many push-type retainers that keep the wiring harness routed in a specific fit unlike the Duramax which has bolt on clips on the harness. The problem with the 6.0 harness is that many technicians do not bother to connect the wiring harness retainers so the harness sits on top of the intake manifold and can potentially rub through on an intake manifold bolt or stud.

This particular 6.0 Powerstroke experienced just that. It was towed in as a no-start and the customer told me he had parked the truck and went back to crank it and it just turned over but would not start. The most cause of this issue in a 2005-2007 is a possible high pressure oil leak. After connecting the scanner we verified that the high pressure oil pump was putting out correct pressure (550 psi+) to crank but we noticed that there were 2 codes stored in memory. P2614 and P2617 are camshaft and crankshaft position sensor circuit codes. To an inexperienced technician, the repair would possibly involve replacing the cam or crank sensors but in my experiences I’ve only changed 1 cam sensor and 0 crank sensors. They just never go bad. I have however had several trucks with damaged wiring harnesses that would cause a loss of cam and crank signals. The easiest way to test for a wiring harness short is to take a piece of wood and push on the harness on top of the engine near the turbo and near the FICM (fuel injector control module). We wiggled the wires around near the FICM and the truck started right up. As I would massage the harness the truck would randomly stall and surge. I decided to get a better look at the harness and after unplugging it from the FICM we found this. You can see the red and yellow wires rubbed through to the metal wiring. This was intermittently shorting to the intake manifold bolt and causing a stall.


Got an intermittent no start hot or cold?? Check your injector and engine wiring harnesses. Thanks. AJ

7.3l Powerstroke no oil pressure

Powerstroke 7.3l and 6.0l engines use a high pressure oil system to fire the fuel injectors. This system uses engine oil under high pressure combined with voltage from the injector module in order to push the fuel (45-65 psi) out the tip of the injector. This system works great when it has no leaks and allowed for the earlier Powerstrokes to achieve higher injection pressures to atomize the fuel and burn cleaner. The problem with the high pressure oil system stems from it’s tendency to develop leaks and also the fact that the engine can not run without base oil pressure (which can be a benefit being you can never run the engine with no oil). The truck I’m gonna talk about today is a 1997 F-250 that was towed to our shop after a previous shop had built the engine but could not get it running.

When we first started looking at this truck we connected the scanner so we could verify how much injection pressure the ECM was seeing. One thing we noticed immediately was that we had 0 psi of injection control pressure. This is important to note because most systems even with a major leak or failed IPR valve with build SOME injection pressure. Normally if you don’t see any ICP (Injection control pressure) there is a low pressure oil problem. We verified this by checking for oil in the high pressure oil pump reservoir. In the picture before I got off a Ford forum you can see the allen-head plug that you remove and then stick a screwdriver in the hole and oil should be filling it up to around 1/2 inch from the top. On this truck it was completely empty.

HPOP R copy

After seeing the reservoir empty, we cranked on the engine for a few minutes and no oil ever came into the reservoir. This indicated that the low pressure oil pump was not functioning. We decided we needed to tear down the front of the engine to check out the pump.

The LPOP (low pressure oil pump) on a 7.3l Powerstroke sits on the crankshaft behind the harmonic balancer. As the crankshaft turns, the gears turn within themselves and this motion creates a film of oil that then picks up from the oil pump and is distributed throughout the engine. This film of oil that creates suction and pressure is very crucial to the operation of the oil pump.

OilSystemFlowDiagram 7.3

IMG_2118 (800x533)

On the 7.3 Powerstroke this oil pump CAN be installed incorrectly which is what I was thinking when they had just rebuilt the engine and installed a new pump. After removing the oil pump we did in fact verify that it was installed backwards. In the picture above you will note the word damper. This word should face toward the damper or the harmonic balancer and they had installed it facing toward the engine.

When the pump is installed backwards on this engine it “eats” a groove in the timing cover that makes it impossible to build up oil pressure again. In the below picture you will see a sizeable groove worn in the front cover. This kind of damage is irreparable.

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To fix this costly mistake we had to replace the front timing cover and oil pump.

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If you have a Powerstroke that is having trouble building oil pressure the LPOP is a good place to start and if you have any questions call me at 706-677-0060. Thanks, AJ

Isuzu Truck service Athens, Ga

Isuzu trucks are some of the most versatile diesels on the road. They are used commonly in landscaping companies, tow companies, and aftermarket parts suppliers. When running correctly, the Isuzu truck can carry a large load and gets much better fuel economy than the bigger diesels out there. 441 Diesel has recently invested in the IDSS diagnostic software from Isuzu. This allows us to have the capability to program ECMs, perform diagnostics tests, and adjust vehicle top speed without having to send trucks out to Isuzu dealers. If you have any questions for us about our Isuzu capabilities call us at 706-677-0060.