Why Did The PM Percentage Drop?

[MTBob]

For several weeks I used my tractor (L6060 HST) lightly and intermittently. As expected, during that time, the PM reading gradually increased, eventually reaching about 94%. I then mowed about 15 acres of pasture and expected the PM amount to rise to 100% and then go into regen. But, it didn't. Over the several hours I mowed, the PM level gradually dropped, eventually leveling out at around 50%.
Having never operated a Kubota with a DPF, I'm not too sure what do expect. Is a drop in the PM values normal in situations like this?

 

[Scottly]

For several weeks I used my tractor (L6060 HST) lightly and intermittently. As expected, during that time, the PM reading gradually increased, eventually reaching about 94%. I then mowed about 15 acres of pasture and expected the PM amount to rise to 100% and then go into regen. But, it didn't. Over the several hours I mowed, the PM level gradually dropped, eventually leveling out at around 50%.
Having never operated a Kubota with a DPF, I'm not too sure what do expect. Is a drop in the PM values normal in situations like this?

I think it dropped simply because you did run the tractor for a long period and cleared the soot from the exhaust.
I work in a heavy truck garage and can say the trucks that get driven harder go through less regens then those that get driven on slow short multiple stop routes.

 

[whitetiger]

For several weeks I used my tractor (L6060 HST) lightly and intermittently. As expected, during that time, the PM reading gradually increased, eventually reaching about 94%. I then mowed about 15 acres of pasture and expected the PM amount to rise to 100% and then go into regen. But, it didn't. Over the several hours I mowed, the PM level gradually dropped, eventually leveling out at around 50%.
Having never operated a Kubota with a DPF, I'm not too sure what do expect. Is a drop in the PM values normal in situations like this?

By loading the engine and increasing the exhaust temp, you were burning the soot, also known as "Passive Regeneration".

 

[85Hokie]

As both said, higher revving engine that is working hard will burn off the particulates, another good reason to work a "newer" diesel hard rather than babying it at lower rpms.

 

[The Evil Twin]

Yup. Passive regen. The EGT was high enough to burn the soot without having to dump fuel into the exhaust.
I've watched it on my truck too. Climbing mountain passes it will burn more than it creates and hover around 30%. Unfortunately it will regen every 500 miles no matter what.

 

[Bmyers]

My L3560 does the same thing. During the summer months I do a lot of mowing, don't remember the last time I needed to do a regen.

Now that temps have cooled, I will start the regen process since I don't run the engine as hot. Winter months, I usually end up with a couple of regens. Summer months, nothing.

 

[MTBob]

Thanks guys! I'm still getting used to how this machine runs. It's reassuring to know that this is a normal process.

 

[McMXi]

Thanks guys! I'm still getting used to how this machine runs. It's reassuring to know that this is a normal process.

You're fortunate to have a gauge or meter for particulates. All I've got are idiot lights that illuminate when it's time to go into regen. The whole DPF thing for these tractors is a disgrace, but typical of the government's tendency to pass meaningless regulations that appear to be meaningful, but ultimately only make life more difficult for many without actually addressing the real problem.

 

[TheOldHokie]

My L3560 does the same thing. During the summer months I do a lot of mowing, don't remember the last time I needed to do a regen.

Now that temps have cooled, I will start the regen process since I don't run the engine as hot. Winter months, I usually end up with a couple of regens. Summer months, nothing.

That seems to be what I am getting with my L3901. Last year fresh off the truck I was kind of babying it and getting regens about every 40 hours. This summer doing a lot of high RPM mowing its over 80 hours (unless I missed it) since the last one. I guess I can quit fretting.....

Dan