Has anyone removed their doc and left the rest of the factory exhaust on? I don't want a louder exhaust I just want the doc off there. It would also be nice if someone made a straight pipe for just that section of the exhaust too.
Correct, can you explain to me what was removed on an LB7 emissions wise? It’s a federal truck so no EGR or CAT, just a muffler. Obviously since it’s a 2002 they didn’t even have a clue what a DPF/DOC was.
You should maybe explain your intentions a little better. You may not know, but we get a lot of similar questions from questionable people on here asking about how to preform illegal mods that we as a community do not endorse. There are legal ways to mod your exhaust and illegal ways. And removing emission equipment is an illegal way
X2, what are you trying to accomplish here? Removing the DOC has basically no benefits. Some people with the LB7 report a tiny mileage improvement removing it. The LB7 came with a DOC in CA, but most states do not require it. So removing it is potentially legal in some states.
Newer models, not so much. It is generally illegal in all states, and as has been mentioned before, the EPA holds the opinion that removing it for off-road use is illegal too. I have my thoughts on that BS logic, but it is what it is.
I don't believe the MPG uplift from removing the DOC is significant, if any, on the newer motors. They will also generally start to throw EGR flow codes, as the slight reduction in back pressure alters the EGR flow. So not only is it illegal, but you'll get a CEL and either have to retune (generally also illegal) or find some other way to keep the EGR system happy.
So what are you trying to do here? In your mind, what is the benefit of not having a DOC?
Diesel oxidation catalyst if I'm not mistaken. As James said, the "CAT". It is essentially the same thing but the composition of catalytic elements has been adjusted to more effectively deal with the difference in diesel exhaust vs gas