Annual Update re Mexican Diesel Fuel
Now that the annual Snowbird migration is underway, I'm already getting emails from owners of 2007.5 through 2013 diesel pickups who are looking for updates on the effects of the higher sulfur Mexican...
Forum Discussion
Regarding the above questions and input:
1.
To The Texan, while it is true that the ECM (onboard computer) registers one or more emissions related codes when there is sulfur poisoning of the emissions system, some of the codes are TEMPORARY, and are erased automatically once the system returns to normal after a regeneration.
I am especially familiar with the programming of the GM systems, much more familiar than anyone at your dealership would be, so I can share with you that the only codes which sometimes remain in the ECM are P2022 and P20EE, neither of which identifies high sulfur fuel as a cause of the code. P2022 indicates that a NOX detector returned a less than specified level of NOX (oxides of nitrogen) in the exhaust, and P20EE indicates that the DPF (diesel particulate filter) returned an error code. A technician seeing these retained codes during a routine read at the dealership, when no engine warning light is lit, would just assume there had been a non-standard event which corrected itself, and he would routinely erase the codes.
There is no code of any type on any of the Big 3 vehicle emissions systems that specifically checks for the presence of sulfur, so it is impossible to tell, after the fact, that LSD was used. If you would like to check the accuracy of this statement, ask your Dealer exactly HOW they can tell that LSD has been used, and what code specifically identifies that LSD was used.
That having been said, I repeat that I do not counsel people to take their trucks to Mexico. I only want to share factual information so that owners can make their own decisions based on those facts.
2.
Regarding the Tiffin with the clogged DPF, I suspect that the author of the letter lacked all the necessary information and/or was given incorrect information by the dealership. Most service reps at dealerships have absolutely NO IDEA how the emissions systems work or how the components interact.
Without having all of the necessary information, I can say that it was not uncommon in 2007.5 through 2010 model years for problems with clogged DPFs to occur because the regeneration cycle was not properly burning out all the sulfur. As a result, over numerous cycles, carbon built up in the DPF and clogged it. SULFUR COMPOUNDS ALONE DO NOT CLOG A DPF - SULFUR COMPOUNDS REDUCE THE EFFICIENCY. I therefore doubt that the Tiffin owner's DPF was clogged with sulfur, and my question to the dealer would be "What scientific tests were done to identify sulfur in the clogged DPF?". I know what the answer would be.
In fact, if the DPF was damaged by sulfur, no warranty would apply, whether or not the unit was in the USA.
As for traveling to Mexico with the Tiffin, I do not have enough information to make a judgement about the risks. Generally speaking, for vehicles prior to the 2011 model year, when urea injection and an SCR were added to the emissions system, no problems occur while in Mexico and owners will not notice any issues or problems. Some will see occasional blue smoke and/or get a temporary engine light and/or Poor Quality DEF warning, all of which go away after the next regeneration cycle.
Also generally speaking, vehicles under load, such as when pulling a large fifth wheel trailer, or transporting a large motorhome body, will have high enough exhaust temperatures to continually burn off sulfur compounds and no fault codes will be seen.
As for whether some "get away" with using Mexican fuel, and some "may not", that is EXACTLY what happens. The vast majority, based on data I've collected since late 2007, experience no issues whatsoever, but there are some every year who come close to going into limp mode, or do go into limp mode, before the fault codes can be cleared. For those folks, I have a database of information built up from the feedback from other owners, along with my technical knowledge of the programming of the system and its components, and I haven't had a case yet where I couldn't solve the issues for the owner. I don't like to see people stranded when I have the knowledge to help fix a problem.
1.
To The Texan, while it is true that the ECM (onboard computer) registers one or more emissions related codes when there is sulfur poisoning of the emissions system, some of the codes are TEMPORARY, and are erased automatically once the system returns to normal after a regeneration.
I am especially familiar with the programming of the GM systems, much more familiar than anyone at your dealership would be, so I can share with you that the only codes which sometimes remain in the ECM are P2022 and P20EE, neither of which identifies high sulfur fuel as a cause of the code. P2022 indicates that a NOX detector returned a less than specified level of NOX (oxides of nitrogen) in the exhaust, and P20EE indicates that the DPF (diesel particulate filter) returned an error code. A technician seeing these retained codes during a routine read at the dealership, when no engine warning light is lit, would just assume there had been a non-standard event which corrected itself, and he would routinely erase the codes.
There is no code of any type on any of the Big 3 vehicle emissions systems that specifically checks for the presence of sulfur, so it is impossible to tell, after the fact, that LSD was used. If you would like to check the accuracy of this statement, ask your Dealer exactly HOW they can tell that LSD has been used, and what code specifically identifies that LSD was used.
That having been said, I repeat that I do not counsel people to take their trucks to Mexico. I only want to share factual information so that owners can make their own decisions based on those facts.
2.
Regarding the Tiffin with the clogged DPF, I suspect that the author of the letter lacked all the necessary information and/or was given incorrect information by the dealership. Most service reps at dealerships have absolutely NO IDEA how the emissions systems work or how the components interact.
Without having all of the necessary information, I can say that it was not uncommon in 2007.5 through 2010 model years for problems with clogged DPFs to occur because the regeneration cycle was not properly burning out all the sulfur. As a result, over numerous cycles, carbon built up in the DPF and clogged it. SULFUR COMPOUNDS ALONE DO NOT CLOG A DPF - SULFUR COMPOUNDS REDUCE THE EFFICIENCY. I therefore doubt that the Tiffin owner's DPF was clogged with sulfur, and my question to the dealer would be "What scientific tests were done to identify sulfur in the clogged DPF?". I know what the answer would be.
In fact, if the DPF was damaged by sulfur, no warranty would apply, whether or not the unit was in the USA.
As for traveling to Mexico with the Tiffin, I do not have enough information to make a judgement about the risks. Generally speaking, for vehicles prior to the 2011 model year, when urea injection and an SCR were added to the emissions system, no problems occur while in Mexico and owners will not notice any issues or problems. Some will see occasional blue smoke and/or get a temporary engine light and/or Poor Quality DEF warning, all of which go away after the next regeneration cycle.
Also generally speaking, vehicles under load, such as when pulling a large fifth wheel trailer, or transporting a large motorhome body, will have high enough exhaust temperatures to continually burn off sulfur compounds and no fault codes will be seen.
As for whether some "get away" with using Mexican fuel, and some "may not", that is EXACTLY what happens. The vast majority, based on data I've collected since late 2007, experience no issues whatsoever, but there are some every year who come close to going into limp mode, or do go into limp mode, before the fault codes can be cleared. For those folks, I have a database of information built up from the feedback from other owners, along with my technical knowledge of the programming of the system and its components, and I haven't had a case yet where I couldn't solve the issues for the owner. I don't like to see people stranded when I have the knowledge to help fix a problem.
