Af ecodiesel service page 2 allpar forums gas vs diesel generator


Click to expand…This could be an issue but has been over hyped somewhat by repair facilities. DEF has to meet ISO 22241—Which is an international standard that defines the quality requirements for DEF including production, storage and distribution. The production, handling and transportation of DEF is governed by the ISO 22241 standards. There could be "boot legged" DEF so the consumer must check and look for the standard that is printed on the container.

Early in the life of the Ram Ecodiesel V6 owners were getting an instrument panel display message "incorrect DEF see dealer" . Unknowing service facilities were telling owners they used incorrect DEF, only use Mopar branded DEF, the DEF system is ruined, and this repair is NOT covered by warranty. The logic in the PCM was comparing the downstream NOX sensor signal to the upstream NOX sensor signal. If it did not see a reduction in the range of 70% or greater, it was assumed that the DEF was bad or contaminated.

After many complaints FCA realized that this was a very misleading and incorrect message. Wiring problems, a failed DEF injector, failed SCR catalyst, or DEF injector that accumulated scale and deposits could all cause an improper dosing of DEF and thus the message. DEF quality was not the real issue. Even GM got caught with this erroneous message early in year 2011 when it first implemented DEF injection on its Duramax equipped diesel vehicles.

Why did the engineers allow such simplistic and incorrect software logic in emissions monitoring? On gasoline powered vehicles with OBD II emissions (1996 and later vehicles) a downstream oxygen sensor that initiates a sensor signal within 90% of the switching rate of the upstream oxygen sensor generates the infamous diagnostic code P0420 – catalyst efficiency. The code does NOT imply poor quality gasoline.

Click to expand…Some sulfur was welcomed in diesel fuel. It helped provide lubrication to those closely machined tolerances in high pressure fuel injection pumps and injectors. As research into electronic fuel injection control developed on diesel engines, it was found that to meet ever stringent emission standards, it would be necessary to have more than 1 fuel injector pulse per power cycle on a 4 cycle engine. Electro magnetic pulsed injectors did not have the quick response desired. Piezoelectric injectors that use electrical energy to open and close an injector provided the desired rapid response rate. A side benefit of using piezoelectric fuel injection allowed engineers to develop reliable starting in diesel engines down to -20 deg F without requiring engine block heaters, starting fluid, etc. This was just not possible on older diesel engines with mechanical fuel injection.

As is typical with engineering challenges, one solution to an emissions problem creates new challenges. It was found that the sulfur concentrations in diesel fuel would contaminate and render the piezoelectric injectors not functioning. So the US Environmental Protection Agency (EPA) mandated that in year 2006 ultra low sulfur diesel be made available for use in diesel powered vehicles.

Pipeline companies first noticed the lowered sulfur content in diesel fuel. Pumps on pipelines starting failing due to lack of sufficient lubrication. The answer was to add lubricity agents to ultra low sulfur diesel fuel. Hopefully that will help solve lubrication problems in high pressure diesel engine fuel injection systems.

Sulfur in the combustion chamber combines with oxygen to create sulfur dioxide. It does not directly create soot. However the oxygen molecule that bonds with sulfur to create sulfur dioxide means there is less oxygen available to support complete combustion. Less oxygen leads to Incomplete combustion which contributes to the creation of soot or unburned hydrocarbons.