This from the
http://freeautoadvice.com/diesel/fuel.html web site:
The HEUI is hydraulically actuated by high pressure engine oil supplied by a gear
driven high pressure oil pump. There are four major components that make up the injector. They are the solenoid,poppet valve, intensifier piston and plunger, and the nozzle assembly.
The Powerstroke has had a few injector oring upgrade’s since 94. Also the injectors themselves have been improved. The new one’s are called split shot injectors or prime injectors. They have been used in California engines since 1996 model year and they are in all 1997 econolines. Now prime injectors are used in all Powerstroke. The prime injectors are lot quieter than the older injectors. They work by firing a small amountof fuel first and then the rest of it. This helps to create a slower flame front and quiet down the racket especially at idle. The clearances in the injector are extremely close and they hate contaminated fuel and water, so be sure to change the filter often and use good quality fuel. A good fuel additive is important in winter months.
Fuel Quality
A major percentage of all problems with diesel engines are related to fuel quality. Diesel fuel can sometimes vary from one shipment to another or from one area to another. Customers also switch from one fuel vendor to another and suppliers sometimes change the fuel they are
offering. The three things that vary the most in diesel fuel are cetane, weight and viscosity. Cetane is defined as the susceptibility of the fuel to self ignite. Acceptable cetane levels are between 40 and 45, however, very few fuel distributors advertise this since each batch may be different. Cetane can influence both starting and combustion roughness of an engine. High altitudes and low temperatures demand increased cetane number of the fuel.
The weight of the fuel or specific gravity plays a major role in the heat content of the fuel. Number 1 is a "lighter" grade while number 2 is "heavier" or weighs more per gallon. While the lighter fuel (#1) has a lower "cloud point" and may provide better starting in cold temperatures, the heavier fuel(#2) has better lubricating qualities and actually contains more heat units (BTU’s) per volume. Assuming the fuels are the same price, better fuel economy is obtained by using #2.
The third aspect of fuel to consider is viscosity. Since "lighter" (#1) fuel is less dense it becomes thinner when heated than the heavier #2 fuel. When this occurs more fuel begins to leak through the high pressure parts of the injection pump which actually caused the injection pump to pump less fuel. As the fuel temperature continues to increase, more fuel is lost through leakage and this results in a power loss of between 1% and 7%.
Taking all these things into consideration buying #2 diesel fuel is the best all around fuel for the diesel engine. There are fuel treatments available to deal with cold weather, low lubrication, qualities, and unknown cetane content of diesel fuel. Buying fuel from a reputable dealer is a good way to insure high quality fuel. The best ones seem to be places that move a lot of diesel fuel such as truck stops, etc. The only way to insure your fuel quality is to treat it yourself and since every tank may be different every tank will need to be treated.
Why do I need to add an additive in my diesel fuel?
A better word for additive would be treatment. A treatment is needed when the diesel fuel is lacking a substance or has a contaminant. This is very obvious in winter time when the temperature gets cold enough to wax up. Treatment with a winterizer lowers the wax point of the diesel fuel to a lower temperature similar to the way adding antifreeze lowers the freezing point of water. The most common reason for treating diesel fuel is to provide extra lubrication. Almostevery fuel injection component requires the diesel to lubricate at least some part of that component. Since low sulfur fuel was introduced, the lubricating quality of diesel fuel has varied greatly. Some suppliers put in an additive for this and some do not. Each tank of fuel you fill up with can be different. Since low sulfur fuel began being used in on-highway vehicles we've seen the life expectancy of the fuel injection system drop as much as 25%. This is great for the repair business but bad for diesel vehicles in general especially since fuel injection components keep getting more and more expensive to repair. Taking this into consideration, treating diesel fuel with a lubricant is more like an insurance policy against wear and although it does not stop the wear, consistent use can delay repairs considerably. However, caution should be made not to treat your fuel with an additive containing ALCOHOL. The alcohol has been proven to deteriorate some fuel injection components quicker and could even cause long term engine damage. With an additive like Stanadyne Performance Formula you not only get the winterizer and the lubricant amongst other benefits you also get a 5 point cetane increase and in turn up to an 8% fuel economy gain to help pay for the protection you get by adding the lubricant.
The FP has been tested on various fuel metering components, including
carburetor o-rings and fuel injector seals. No deterioration has been noted. It appears that fuel quality would be more of a major concern that a fuel additive containing cleaners.
[ November 21, 2002, 02:54 PM: Message edited by: MolaKule ]