Soot level troubleshooting

Had the same problem as before. As soon as I hit the derate, the engine sound smooths out and the exhaust temperatures drop. The soot level decreases, and then as soon as it lowers to the "A" for regen, it starts sounding rough again. Shortly after that, it will begin rising again. For the longest time it kept between the A and the 2, so it wouldn't derate but it also kept trying to regen. The exhaust temperature would hit 900 and the turbo would limit the amount of boost I could use. If I lock it into 11th and set the cruise at 55 (1400rpm), the temperature stays between 750-850 and the soot level drops. No matter how I drove in 12th, it would stay 850-900 or lose too much speed to stay in gear.

 

Started the day with the same symptoms, so we stayed in 11th and kept temperatures below 750. The soot gauge level was dropping steadily. After stopping at an intersection, the soot gauge went to 200% full before we could hit 55 mph and derated us. When we stopped at the intersection, it sounded like warm hold function was active, like the turbo was still spooling at idle.

Fuel mileage has been around 6 mpg loaded with a flatbed for this run. Since the last oil change it's been 6.6 mpg total. IFTA reports have been pretty consistent between 6-6.5, so I don't feel like it's creating excessive soot through incomplete combustion. I'm going to check out the DRV I guess. It seems like it's related to exhaust temperatures, as well as maybe affecting boost pressure. It still seems to work fine when the truck starts, though.

 

We smoke tested the exhaust, tested the injectors, checked the turbo actuator, and the EGR valve. Everything checked out except the EGR valve. Since the cooler comes off to replace the valve, we're having it cleaned. EGR valve bolt broke upon removal, so we decided a new exhaust manifold would be our best course of action. I should know if it's fixed around Wednesday, I'll update when I know more.

 

Finally got the truck back this morning and ran it about 200 miles or so. EGT never went over 800 that I saw, regardless of what RPM and boost level I was at. They performed a regen at the shop before I left, and it's kind of settling around the 40% mark. I've only got like 4 pallets of lava rock on the trailer, so I'm not sure how well I'll do under a full load. I did hit some small hills going from CO Springs to Denver, so I was able to work it a bit.

The reason it took so long to get fixed, was because Volvo had an updated harness on the new EGR valve that apparently doesn't come included with it. The EGR valve we ordered from a 3rd party got there really quick, but for some reason, all of the parts they ordered through Mack/Volvo took like 4 or 5 days to get in. The whole process took entirely too long. Hopefully this fixed it. I'll update if it doesn't.

 

I got about 800 miles of problem free running and then injector #2 gave out. Coolant and oil temps have been normal, but the soot gauge is back to acting up again, rising until derate and falling back to the "A". It sounds smoother when it gets derated, and gets rough when it hits the A mark again. I'll get the injector swapped out and have an overhead performed, and hopefully that should do it.

The OTR performance tool will clear the injector code so I can clear the soot level and any derate codes if necessary. I haven't tried to perform a regen and don't think I'm going to bother with only 5 cylinders firing.

 

It was acting normally during those 800 miles. Fuel mileage was good and the soot gauge stayed around the 30-40% mark. But I do believe the injector was leaking or something before it finally stopped working. When the truck was coasting/decelerating, I could hear a kind of chug a chug sound like combustion was happening. As soon as the injector failed electronically, that noise went away. Another problem was when starting the truck, the starter would turn and then pause for like a second before turning over normally. After the injector failed, it no longer has that pause. The injector was intermittently cutting in and out when I noticed these symptoms. Now I think it's out for good, though.

I don't think the filter is plugging up, and it should burn up when exhaust temperatures reach 800+ and it starts dosing. The opposite is happening, though. The soot level raises with temperature, and then when it derates and temperatures are 600-650, the soot level gets lower. I just wish I could figure out the misfire/pinging noise that happens every time it hits the "A". It makes me worry about the other injectors a bit.

 

Since the injector was replaced and valves adjusted, the soot level has been sitting around the 20-25% area for the past 2000 miles or so. I've still got a slight noise that could be a spring or something from one of the injectors, but it doesn't seem to be getting worse and my fuel mileage is where I think it should be.