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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.
 

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Discussion Starter #22
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?
 

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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.
 

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Discussion Starter #24 (Edited)
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.

87123
 

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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.
 

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Discussion Starter #26
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.
 

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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.
 

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Discussion Starter #28
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.
 
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