Correct. The purpose of the egr is removing the amount of NOx from the atmosphere(acid rain and smog). Rerunning the exhaust gas does this, but along with higher concentration of NOx(nitrogen oxide) is increased S02(sulfur dioxide) and Water. When they cool everytime you shut off the engine, it forms sulfuric acid,nitric acid, and a little hydrochloride.
Happy high sulfur diesel didn't have the problem, although it made tons more S02, the h20 was higher- the end ph was lower, so basically it waters down the acid as it formed. Scientific arguments still abound over details in fixing it long term. They say cost to end user of damage is worth the gains of humanity, so that's where we are now.
One option is kill the egr as long as you don't have to smog your diesel yet.
The other short term answer for us the Guinea pigs that want to sacrifice a little more smog today, and have a smaller carbon footprint long term is (like how I won the arguement before treehugger Timmy could comment) raise the carbon count ever so slightly going into the fuel, which raises the ph. How? What additive?
Used engine oil. Remember the fuel additive for ulsd and when the Gubmint did all the testing (I was part of that through 76 oils). Then later a bunch of forum guys did there own testing (if I was good at finding things I would insert the link here, Please post it below if you know what I'm referring to) and used engine oil was found to be really good, at 1 qt. added? Especially compared to some expensive additives? I said then- used engine oil is free, use slightly more than 1qt per tank (25 gal) used in the testing. We found 1qt per 20 gallons is the magic. Plenty of lube to loose no life off ip or injectors. I also said it helps valves, pistons, and pistons rings. 99.9% of people scoffed. I laughed and say "ok"
<--sarcasm font applied.
