[Brokedownbutgood]

Had a customers truck come in (not an ecodiesel or even close an x15) but they had pulled the dpf and had it cleaned but were still having regen issues. After I pulled the steps one of the dpf pressure lines was completely off the sensor and causing a constant high pressure differential. Yes a issue with one of those hoses or lines would cause regen issues.

 

[phprof]

I'll give it another look this weekend. It's hard to see up there. It's all that makes sense to me.

Another question. Does the sensor read the pressure "directly" or does it work by detecting a drop in pressure as exhaust moves past an open tube and then uses a correlation to compute the pressure?

 

[Brokedownbutgood]

I'll give it another look this weekend. It's hard to see up there. It's all that makes sense to me.

Another question. Does the sensor read the pressure "directly" or does it work by detecting a drop in pressure as exhaust moves past an open tube and then uses a correlation to compute the pressure?

There well be a positive pressure but its fairly low.

 

[phprof]

There well be a positive pressure but its fairly low.

Copy that. Thanks. Hmmmm .... gets my wheels turning.

Edit: Just crawled under it. No way I can get it out to look at or replace the hoses. I might be able to get at the bolts if I remove the right front wheel and the fender liner.

For those that are curious, here is an image of some recent data. I did a test yesterday with some hard accelerations to simulation large power requirements. The same thing happens when towing. Engine speed in blue and DPF loading x 50 (for scaling) in red. As engine RPMs increase rapidly, the DPF loading skyrockets. Once settled into a constant speed, the DPF loading will fall slowly. It looks like a decay curve to me. Something I see in some physics labs. Like a slow leak on a pressure vessel. You pressurize it quickly then it slowly loses pressure. In this case, it's a differential pressure between two points in a pipe.

 

[GDE]

It is a delta P sensor as there is one port before dpf and one after. The soot model in the stock calibration does rise with increasing load. This is offset by the exhaust temps. If in the 450-600 C range (think trailer towing) the soot load may actually decrease in spots if the passive regeneration is taking place.

 

[phprof]

It is a delta P sensor as there is one port before dpf and one after. The soot model in the stock calibration does rise with increasing load. This is offset by the exhaust temps. If in the 450-600 C range (think trailer towing) the soot load may actually decrease in spots if the passive regeneration is taking place.

Okay, so what could cause the large rises (then decreases) in soot loading during non-towing or scenarios which is represented in my previous post? That was me just out pounding on the throttle and then letting the truck settle in for a constant speed segment without our trailer. In 2019, I pulled our 5800lb travel trailer to Ohio and back (670 miles one way) with some time at the Henry Ford complex/museum (highly recommended, by the way) and I noted the increases and decreases in soot loading as DPF temperatures rose and fell on the highway. All looked normal as per what I had read. Now its mostly just one way with the exception of dropping during lower engine RPMs. That doesn't jive in my head. If it's got soot it should have soot, right? So, either my truck is generating more soot than a JD 4020 tractor pulling a plow or something is definitely wrong with the emissions system.

Got to get this sorted out. Running regens every 25-40 miles isn't cool.

Edit: By the way, thanks for all the ideas forum members.

 

[GDE]

It pretty much smokes a lot when you hammer down with the stock tune. If you are doing all city driving with AC it can regen every 30-50 miles. Up to 175 miles if doing more highway. The stock combustion is not efficient.

 

[phprof]

It pretty much smokes a lot when you hammer down with the stock tune. If you are doing all city driving with AC it can regen every 30-50 miles. Up to 175 miles if doing more highway. The stock combustion is not efficient.

I agree the stock tune isn't great. You magicians at GDE have proven that. However, what I am seeing is a real problem. It was a sudden change that occurred on May 21st while pulling my trailer home from storage. Prior to this, my typical daily driving was about 120-125 miles between regens and on long trips to see family I saw over 300 miles between regens.

Just found out a friend has a lift in his garage. Going to pull the right front tire and fender liner and get at that sensor.

 

[phprof]

So I thought it was getting better. Seemed early last week to stop acting funny. Normal build up of soot until about Wednesday. Then it started doing it again. After doing some more reading on the DPF and soot computation from GDE, I suspect an issue with a sensor. Temperature sensor(s), MAP, MAF, gas flow rate, torque demand/production estimation, etc. The issue is exasperated with engine RPM/torque demand. Put the foot to the floor (going up hill is worse than flat ground) will cause a 10-20% rise in DPF soot load and upon letting off the pedal and allowing to coast or cruise on level ground it will decrease back to ~where it was. Fuel mileage is 24-25 MPG driving around the UP of Michigan and power feels fine. Response is normal.

Could it be a bad software write from the VA7 (updated AEM) back in April?

 

[Ecosparky]

If the soot level increases and decreases with throttle input and loading but returns back to normal then wouldn't this be normal? OR are you still seeing an increase in active regenerations?

 

[97hmcs]

So I thought it was getting better. Seemed early last week to stop acting funny. Normal build up of soot until about Wednesday. Then it started doing it again. After doing some more reading on the DPF and soot computation from GDE, I suspect an issue with a sensor. Temperature sensor(s), MAP, MAF, gas flow rate, torque demand/production estimation, etc. The issue is exasperated with engine RPM/torque demand. Put the foot to the floor (going up hill is worse than flat ground) will cause a 10-20% rise in DPF soot load and upon letting off the pedal and allowing to coast or cruise on level ground it will decrease back to ~where it was. Fuel mileage is 24-25 MPG driving around the UP of Michigan and power feels fine. Response is normal.

Could it be a bad software write from the VA7 (updated AEM) back in April?

Without me looking back, can you tell me what monitor you are using?

 

[phprof]

If the soot level increases and decreases with throttle input and loading but returns back to normal then wouldn't this be normal? OR are you still seeing an increase in active regenerations?

In the past, soot would only increase unless I was towing heavy and got the DPF hot enough. Did not happen much but I did see it last summer. What I am see here is increase in DPF load when the truck is output higher power outputs. Example: Climbing hill out of my local town of work. It's about a 6% grade for a bit over a mile. I pull 7th gear at just over 2200 rpms. Soot load will increase by 10-15% or more. Once at the top and it goes into 8th gear and the road levels out it slowing drops back to where it was before I started the climb.

Without me looking back, can you tell me what monitor you are using?

I'm using a BlueToothe adapter with Torque Pro app on my phone. I monitor EGTs, boost, DPF, regen, and couple other items. I've been using since January 2019.

 

[97hmcs]

In the past, soot would only increase unless I was towing heavy and got the DPF hot enough. Did not happen much but I did see it last summer. What I am see here is increase in DPF load when the truck is output higher power outputs. Example: Climbing hill out of my local town of work. It's about a 6% grade for a bit over a mile. I pull 7th gear at just over 2200 rpms. Soot load will increase by 10-15% or more. Once at the top and it goes into 8th gear and the road levels out it slowing drops back to where it was before I started the climb.



I'm using a BlueToothe adapter with Torque Pro app on my phone. I monitor EGTs, boost, DPF, regen, and couple other items. I've been using since January 2019.

In the past, soot would only increase unless I was towing heavy and got the DPF hot enough. Did not happen much but I did see it last summer. What I am see here is increase in DPF load when the truck is output higher power outputs. Example: Climbing hill out of my local town of work. It's about a 6% grade for a bit over a mile. I pull 7th gear at just over 2200 rpms. Soot load will increase by 10-15% or more. Once at the top and it goes into 8th gear and the road levels out it slowing drops back to where it was before I started the climb.



I'm using a BlueToothe adapter with Torque Pro app on my phone. I monitor EGTs, boost, DPF, regen, and couple other items. I've been using since January 2019.

If you are seeing a 10-20% rise in DPF soot load and upon letting off the pedal and allowing to coast or cruise on level ground it will decrease back to ~where it was , I wonder if your BT adapter is giving false readings?

 

[phprof]

If you are seeing a 10-20% rise in DPF soot load and upon letting off the pedal and allowing to coast or cruise on level ground it will decrease back to ~where it was , I wonder if your BT adapter is giving false readings?

That crossed my mind as well but why now? Why May 21st and onward but not before? Can it cause a feedback that would trigger the ECU into a regen?

 

[97hmcs]

That crossed my mind as well but why now? Why May 21st and onward but not before? Can it cause a feedback that would trigger the ECU into a regen?

Those BT adapters often fail and have been known to light up the dash and trigger numerous codes. I don't know if it's possible to initiate the rege, but I would't rule it out.
Why may 21st? Could simply be the day the adapter failed??? I don't know exactly which adapter you are using. The inexpensive (knock-off) adapters can be problematic to say the least.

 

[dak8200]

I've watched my cat11 temp whe driving and monitoring the DPF regen percentage. I don"t know if it's feed forward or watching several other variables, but mine jumps up and down. Seems to be related to RPM/load and cat11 temp being well over 800F when not in regen. Does anyone know the variables / algorithm used for regen % or is it straight off of DPD dP?

 

[97hmcs]

I've watched my cat11 temp whe driving and monitoring the DPF regen percentage. I don"t know if it's feed forward or watching several other variables, but mine jumps up and down. Seems to be related to RPM/load and cat11 temp being well over 800F when not in regen. Does anyone know the variables / algorithm used for regen % or is it straight off of DPD dP?

I have never seen any fluctuation using the edge monitor. One time I did see the soot % go down a couple percent (passive regen maybe) while towing heavy in the mountains. I think some of the software programs also will show soot at 100% when regening and that's not correct.

Soot Loading Strategy (Quoted from Forum Sponsor GDE)

The ECU runs two different strategies in parallel and takes the higher of the two outputs to determine the current soot loading:

Strategy 1 is a simulated value, and is calculated according to how complete the previous regeneration was, and how the engine/vehicle has been operating since then (engine speed, load, ambient conditions, exhaust temps, etc). Different OEMs design different variations of such a strategy, but for the most part the high level concepts are similar. The strategy employed by the Ram's stock tune is fairly rudimentary.

Strategy 2 is a physically measured value calculated off of measured pressure drop across the DPF, the DPF temperature, and the known flow rate of exhaust gasses.

The soot loading is used to trigger the regeneration when all the correct criteria are met.


Just as a note for some more info...

Passive regens happen when there is sufficient exhaust temperature and a favorable NO2/NOx ratio for the soot to burn. This phenomena will happen starting with exhaust temps in the 380-400°C range.
However...the stock tunes are not capable to detect that passive regeneration is taking place, and to thus slow the modeled accumulation of soot and/or decrease it if the burn rate exceeds the production rate. This is why the intervals are not improved more in the highway cycles.

...we fixed this with our tunes, in order to avoid regenerating when it's not necessary.



the DPF is made to withstand a certain number of regens by being taken to very high
temperatures , so the less regens the better.

 

[phprof]

I have never seen any fluctuation using the edge monitor. One time I did see the soot % go down a couple percent (passive regen maybe) while towing heavy in the mountains. I think some of the software programs also will show soot at 100% when regening and that's not correct.

the DPF is made to withstand a certain number of regens by being taken to very high
temperatures , so the less regens the better.

That was my experience prior to this occurring in May. I'm going to run without my monitor and attempt to check only periodically. Starting to think my adapter/software is the issue. Just never thought it could cause this kind of response and have it tied to RPM/exhaust gas volume flow.

 

[97hmcs]

That was my experience prior to this occurring in May. I'm going to run without my monitor and attempt to check only periodically. Starting to think my adapter/software is the issue. Just never thought it could cause this kind of response and have it tied to RPM/exhaust gas volume flow.

Please keep us posted. What adapter are you using? Do you have access to another to try?

 

[phprof]

Please keep us posted. What adapter are you using? Do you have access to another to try?

el cheap'o BAFX OBD2 Android Bluetooth Wireless OBDII Reader & Scan Tool - For Android Devices Only

On trip home, used it to check DPF before I left work. 22.5%. Pulled it and drove to the top of the hill coming out of town. 6% grade for about 1 mile after 3 round abouts and the nuts. After clearing the top of the hill and leveled out, plugged in and brought up Torque Pro. 26.4%. Rats. I'll check it again throughout the rest of the week but it looks like the OBD2 reader is gone or the software has a glitch.

Time to save pennies for CTS and a tune.