I have been reading about the Duramax on The Diesel Page for about 3 years and about the Cummins on the Turbo Diesel Register for about two years. Each site is visited daily. I have little interest in Ford because it doesn't really meet my needs so I only occasionally read about the new Powerstroke.
The durability of fuel injectors seems to be a troubling question and perhaps a real concern to some of us who currently own or are considering the purchase of a new diesel with the latest High Pressure Common Rail fuel injection system. GM is already into their third or fourth generation of injectors and from what I read on the various sites, Ford is also into their third or fourth generation of injectors for the new Powerstroke. We shouldn't be a bit surprised if Cummins also goes through these birthing pains with this new and better technology.
I have no idea what the problems have been with the injectors on the new Powerstroke but I will interpret what I have read on The DieselPage about the few injector problems on the Duramax. Much of this information, I am certain, will be very helpful to Cummins owners. For about the last three years some very bright and technically certified persons have been researching an apparent "injector problem" with some (not many) of the Duramax Diesel engines. Here is my summary what they have found: Most of the Duramax engines have no injector problems at all. Many of those with injector problems have been studied very carefully to determine the cause of the problem. After looking at the tips of the "defective" injectors under an electron microscope they noticed that very few of the injectors were clogged with pieces of rust or other debris. Most of the "defective" injectors had their tips eroded by what appears to be a "sand blasted" condition. Further study showed that this sand blasted erosion is caused by 5 micron to 10 micron sized particulate matter in the fuel. Each minute, millions of these microscopically small particles of debris are blasted through the injectors under very high pressure. The "sand blasting" effect of these small particles is actually wearing away the tips of the injectors, thereby causing defective operation. The first couple of injector designs were not that great. However, the latest generation of injector appears to be very reliable and what some would consider to be an "injector problem" now appears to be really a "fuel problem".
None of this research is 100% conclusive but all studies so far seem to point to fuel quality as being the cause of the "injector problem" in these HPCR injection systems. If dirty fuel is causing the problem, there would seem to be three ways to solve the problem: 1) clean up all the diesel fuel in all the stations which sell diesel fuel. This is obviously not a practical solution so the next best solution is to purchase your fuel from a reputable dealer or at least one that sells lots of fuel. You would be horrified at the amount of dirt, algae and water in the diesel fuel pumped at some stations; 2) Install a better fuel filter. The current thought is that if one could install a fuel filter which is guaranteed to filter out all particulate down to the 2 micron range the "sand blasted" effect would be reduced and possibly eliminated. Fuel analysis, pre and post filtration have been conducted to determine the effectiveness of the fuel filters. It was learned that just because a fuel filter has a 2 micron rating does not mean that it will filter out 100% of all particulate down to 2 microns in size. Fuel filters of the same rating from different manufacturers do vary in their effectiveness at filtering fuel. Fuel filters have been cut in half to determine where water and debris are being trapped within the filter. It was thought this process might lead to a better filter design. Some owners are currently looking at installing a secondary fuel filter to help solve the particulate problem. However, fears of reduced fuel flow and reduced fuel pressure are causing people to move slowly in this direction; 3) Develop a material hard enough to withstand the "sand blasting" effect of these microscopic particles of debris and use this material to manufacture the tips of the injectors. This might be practically impossible and would definitely make an already very expensive injector even more so.
The big three auto manufacturers will do more research into the effects of diesel fuel quality on the performance of these newest HPCR fuel injection systems. Until their results are conclusive, it seems that we all need to proceed slowly and let's not start seeing problems where there might not be any. Continue to be aware of where we purchase fuel and change filters regularly. Like all new technologies this HPCR system will have growing pains. In my opinion "injector problems", if there are any, will be history within the foreseeable future (next year or two). Manufacturers also want this newer technology to be huge success. They have too much invested to allow failure.
If you still have a lot if interest in the "injector durability" issue, I would encourage you to put aside brand loyalties for a moment and read about this topic with an open mind at the Duramax site. Both the TDR and The Diesel Page have serious people who really want to solve problems, help each other, and advance the diesel technology.
Here is a link which discusses the importance of clean fuel on the performance of diesel injectors. While this article does not deal with the specific needs of the new High Pressure Common Rail systems, it does address the needs of lower pressure diesel injection systems. It would seem that the importance of fuel cleanliness in the newer high pressure systems is even more important than what is mentioned in this well written article.
http://www.fleetwatch.co.za/supplements/SADiesel/DieselDirtS.htm
Best Wishes,
John_M
Attention: TDR Forum Junkies 
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