Ok . Well I've been having the same symptoms. I just changed the dpf Wednesday that's the last thing I've done to the truck but I've changed sensors, the ports were cleaned 2 weeks ago, the injectors we're reconstructed 6 months ago along with the engine rebuilt . I've been having the same symptoms since before the engine rebuilt. Now 6 months later is more severe were the soot goes up in about 160 miles of driving and when the regen kicks in at 3oz of soot while driving , it won't finish the regen and the temps don't go higher than 550. If I do a forced regen with my insite , it lasts about 1 hour and everything is back to normal. I've spent a lot of money and time , I'm going broke and crazy with this truck.
DOC is the first filter that collects the soot, it gets burnt off and collects in the DPF as ash. It can affect soot level and regen temperatures. On Volvo motors, there's also a flex pipe between the turbo and DOC that has insulation fibers that plugs things up. If you had the DPF replaced, I would hope that they inspected the DOC at the same time. If you can't find info on this site, try Rawze for good info on Cummins engines. The only issue I can see is that if your DOC is bad and your regen temperatures are low, then how is soot level going down during regen? When you said you cleaned the ports, are you talking about the pipes that connect to the DPF sensors, or the ports that are part of the venturi pressure sensor? The venturi pipe is on the engine between the EGR cooler and the intake manifold.
If the DOC isn’t doing the job(burn) it’s going to fill up the DPF. Even though it’s new. I had both replaced in my truck. It kept trying to regen every few hundred miles. And when I did a forced regen, it wouldn’t complete it. You can feel the burner trying to do the job and it wouldn’t complete stop. So they hook up the laptop and the DPF showed it was full. So when both was removed, took them to get check out and cooked, they said both were history(shot). So bought both new and never had a problem afters.
Yes the doc was inspected and they said it was fine. I'm confused right there with the doc because on a forced regen everything works good and the soot load goes to 0oz. They cleaned the 2 ports that are under the venturi pressure sensor, i think they said they had to drain the coolant to clean that out. I'm out of ideas , the only thing I've never changed is the egr valve . We can feel if an injector is bad , right? Shaking or making noises or even poor power. Yes the doc was inspected and they said it was fine. I'm confused right there with the doc because on a forced regen everything works good and the soot load goes to 0oz. They cleaned the 2 ports that are under the venturi pressure sensor, i think they said they had to drain the coolant to clean that out. I'm out of ideas , the only thing I've never changed is the egr valve . We can feel if an injector is bad , right? Shaking or making noises or even poor power output.
Thanks for the info, I've never changed the doc either but I'm confused because when I do a forced regen the temperatures work perfectly and the soot goes to 0oz .
Well, this is on Pete what I said on my truck. It resolved my issue. I have absolutely zero knowledge on a Volvo.
