Just wondering why removing DPF would cause "infinite regens" - Ford Powerstroke Diesel Forum
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Old 02-07-2014, 11:58 AM
mpo mpo is offline
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Just wondering why removing DPF would cause "infinite regens"

I have read that you need the tuner to turn off the regens and I have no reason to doubt that information. However, I am trying to understand why. My understanding is that there is a pressure sensor before the DPF that ranges from 0 to 11.6 PSI, and that a back pressure of 7 PSI triggers a regen since that indicates the DPF is getting clogged or "full". So, if there is just a pipe there instead of a DPF, and the back pressure is about 0, then why would a regen ever be triggered?
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Old 02-07-2014, 12:05 PM
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My guess would be the rear sensor (post DPF) would trigger something wrong and put you in limp mode.
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Old 02-07-2014, 12:21 PM
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it reads pressure wether too much or not enough it will put truck in limp mode without fooling pcm with a tuner
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Old 02-08-2014, 10:22 AM
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it actualy has to do with the stock tuning. if you drop the DPF you won't immediately go into limp mode or infinite regen. After so many miles the computer forces a regen. since the pressure sensors won't detect a change from before regen to after regen, the computer won't know when to stop the regen (i.e. infinite regen).

However, if you drop the DPF and don't have the pressure sensors plugged in without tuning it will immediately go into limp mode.
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Old 02-08-2014, 09:19 PM
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[QUOTE=CountryAggie;8164266]it actualy has to do with the stock tuning. if you drop the DPF you won't immediately go into limp mode or infinite regen. After so many miles the computer forces a regen. since the pressure sensors won't detect a change from before regen to after regen, the computer won't know when to stop the regen (i.e. infinite regen).

^^^WHS. One time when I was changing tunes (my DPF had been deleted for 20k miles) when I was running a SCT, a changed tunes back to stock (because that is how you had to change tunes with the LW) and while I was loading a deleted tune, the tuner died. I wasn't sure if the deleted tune was on my truck or not. Started the truck and it ran fine, then after driving a little ways, it started blowing white smoke cause it went into regen. After it started smoking, it wouldn't quit. When I called SCT and asked why that happened, they explained what Aggie said.
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Old 02-11-2014, 03:15 PM
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Quote:
Originally Posted by CountryAggie View Post
After so many miles the computer forces a regen.
Anybody know how many miles?
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Old 02-11-2014, 03:18 PM
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I am curious what exactly it needs to sense to come out of regen. I am fairly sure the last EGT (after the DPF) has to read a high temp. I am not sure it needs to see a change in pressure. I am an electronics engineer and I can spoof any sensor with hardware. If the computer is looking for something simple I could simulate that. However there may be a minimum regen cycle time. It may be impossible to know. Well someone knows...
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Old 02-11-2014, 04:19 PM
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Quote:
Originally Posted by mpo View Post
Anybody know how many miles?
I didn't even make it a mile but I did let the truck warm up for several minutes....and again, I had been deleted for 20k miles when this happened.
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Old 02-14-2014, 11:12 AM
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I'm not sure but I think the main thing is that it sees "some" change between the sensors like a back fault check on a PLC program.
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Old 02-14-2014, 03:28 PM
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It causes infinite regens to remind you that you are being stupid...
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