I had an incomplete regen yesterday around town. I figured today I would drive until it triggered and let it complete. I drove for 80 minutes and 63 miles. The DPF never went into regen. I was at 55 mph and 65 mph for a good fraction of the time. It has been 77 miles since the last regen was requested and it has been 193 miles since the last successfully completed regen.

So what actually triggers a DPF regen? I think today I had enough time, miles, temperatures, etc. Maybe the pressure wasn't high enough but it was the same as yesterday...

Does anyone have a good list of what triggers a DPF regen?

 

 

On Saturday before it started the regen, egt3 was at about 450 F. During regen it was peaking over 1000 F. It shut off early for some reason and did not complete the regen Saturday..

On Sunday when it would not go into regen, there were lots of miles with egt3 above 550 F and above 600 F.

Update! Today, right before I got to work it went into regen again. The egt3 temperature when it did was 464 F. I decided to drive past my usual work turn off and try to get it to finish the regen. I could see the egt3 temperature hit 1000 F but then after a few minutes it went back down to the 400s even though it was still in regen. I kept driving and after a while more it started heating back up to 1000 F and above. Once it went back up, it took 23 minutes but finally finished regen. Took me 45 extra minutes total driving but it finally finished. Now I can monitor and get a better idea of what the PIDs are doing the next time it calls for regen since I can now start from a good baseline.

But that still leaves the question - I have had times when regen was requested, egt3 was above 450 F, and it either did or did not go into regen. So there has to be more than egt3.

What else does the PCM look for to trigger regen once it has been requested?

 

45 minutes sounds righ on the extreme end for active regen.

if you want better passive regens...look into using Lucas dpf clean or similar product

to do a regen

Vehicle speed over 35mph

engine has reached normal operating temp

back pressure sensor on CAT triggers the need for regen....or

its been 600 miles since successful regen...exhuast temp is a fracture in ash burn off.

there is nothing else. Your coolant temp sensor, egt3, and exhuast sensor on cat are the only input signals.


this is my last response to this thread as I feel we are just going in circles.

 

Ok, this is kind of what I was after but I was looking for some numbers to compare to PID data... I still think that the PCM is not starting a regen when it should be.

What is minimum normal operating temp for the coolant temperature sensor?
What back pressure level in psi triggers the regen?
Is 450 the threshold egt3 temperature or is it a different value?

Now that I have had a successful regen I can watch for the 600 mile target.

Thanks

 

I don’t remember the exact number...it’s in the realm of 13 to 16 psi

 

If anyone is interested, here is what the successful regen looked like. The left axis is for EGT3 temperature. The right axis is for the other parameters. Green is EGT3. Gray is DPF pressure. The other colors are easier to see in the legend. The regen kicked in with DPF pressure between 1 and 2 psi, calculated load state bouncing between 3 and 4 (5 is good), and EGT3 temp around 470 F. It quit adding fuel around 1700 seconds for some reason but turned it on again around 2000 seconds and that is when the EGT3 temp finally stayed around 1000 F and finished the cleaning cycle.

 

"the regen kicked in with DPF pressure between 1 and 2 psi"

that's not why it kicked in...it kicked in because you are in default regen mode and you achieve EOT plus 2000 rpms. The PSI to initiate an active regen is 13 to 16 PSI.

your are confusing the 3 different types of regens, AND the default 600 mile regen. this 3 page article should answer most of your questions.

https://www.searchautoparts.com/nace...epair?page=0,0

 

Thanks for the link! Let’s see if I understand now or am still missing something...

I was in default regen because I couldn’t tell my computer that I had a new DPF. It wanted a regen based on the old data. So when it got to engine operating temp it went into regen - didn’t matter what the DPF pressure was at that point.

Passive regen is happening all the time when the egt3 gets high enough - but it doesn’t have to be 1000 F in passive regen, right? Maybe only 600 F? If I add something to the fuel, passive regen could work at even lower temperatures. The computer doesn’t control passive regen - it’s just a property of the materials at temperature?

Active regen will be requested at either 600 miles or if the DPF pressure gets up around 13 psi (or if the calculated soot load gets too high for some reason?). In active regen, that is where fuel makes it to the catalytic converter and egt3 gets up near 1000 F long enough for the computer to be happy. Then it quits adding fuel and egt3 goes back to normal. For me, normal egt3 seems to range from high 300’s to over 600, depending on whether I am on level ground or climbing a hill.

Is that pretty close? Thanks for your help!

 

Your close

make the story about the defualt 600 mile regen a seperate senerio. In that senerio past regens failed and sensor data is questionable...so at 600...the computer tries an active regen once you at eot, rpm above 2000, and speeds over 35. Back pressure psi don’t matter during a default regen. The defualt regen ends when high enough evt’s Are reached.