Replacing DPF's--what does the Tech do?
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From: San Jose, CA
Replacing DPF's--what does the Tech do?
When a DPF is replaced, what is involved?
- Does the tech run any IDS diags or reset some DPF counter in the PCM after installation? Or does one just simply swap it out and send the customer on his way?
I'm wondering because:
- How does the PCM know when the DPF is 'empty' or 'full'? Are there preset ranges based on backpressure, or does the PCM need to 'recalibrate' the DPF by letting it fillup to near 'full' before its first regen?
- Suppose a partially full, but still good, DPF was installed. Does the PCM use that as a new baseline for 'empty'?
Leading to my question:
What happens when a tuned truck is returned to stock? I assume the PCM is completely wiped clear of any previously stored states. Does the PCM assume anything like a perfectly clean DPF and it recalibrates from scratch, or does it simply regen based on how full it thinks it is based on some preset values that decide when 'empty' and 'full' are?
If planning to 'delete' a truck that needs to be returned to stock periodically, does it matter how full the DPF is before tuning/deleting? Or should one let it regen completely before deleting so when the truck is reflashed to stock, it restarts from 'empty'
I hope this makes sense...
- Does the tech run any IDS diags or reset some DPF counter in the PCM after installation? Or does one just simply swap it out and send the customer on his way?
I'm wondering because:
- How does the PCM know when the DPF is 'empty' or 'full'? Are there preset ranges based on backpressure, or does the PCM need to 'recalibrate' the DPF by letting it fillup to near 'full' before its first regen?
- Suppose a partially full, but still good, DPF was installed. Does the PCM use that as a new baseline for 'empty'?
Leading to my question:
What happens when a tuned truck is returned to stock? I assume the PCM is completely wiped clear of any previously stored states. Does the PCM assume anything like a perfectly clean DPF and it recalibrates from scratch, or does it simply regen based on how full it thinks it is based on some preset values that decide when 'empty' and 'full' are?
If planning to 'delete' a truck that needs to be returned to stock periodically, does it matter how full the DPF is before tuning/deleting? Or should one let it regen completely before deleting so when the truck is reflashed to stock, it restarts from 'empty'
I hope this makes sense...
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Joined: Jun 2007
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From: Henderson, NV
There is a exhaust pressure sensor which is used by the PCM to determine when a Regen is required. As the dpf fills up exhaust back pressure increases and PCM initiates a Regen. There are other items that factor Regen but this is the primary as it has been explained to me. With that being said i believe they simply change the DPF when it is defective clear any codes and send you on your way.
If using a tuner u do not have to switch back to stock periodically unless Ur running a large tune which turns the EGR valve off. Some EGR off tunes still cycle the EGR at idle but they can cause the EGR valve to still stick over time. The simple fix is to run a lower EGR on tune for a tank or so periodically or as needed to keep the EGR valve functioning correctly.
If using a tuner u do not have to switch back to stock periodically unless Ur running a large tune which turns the EGR valve off. Some EGR off tunes still cycle the EGR at idle but they can cause the EGR valve to still stick over time. The simple fix is to run a lower EGR on tune for a tank or so periodically or as needed to keep the EGR valve functioning correctly.
Posting Guru
Joined: Jun 2007
Posts: 1,501
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From: Henderson, NV
Im curious is it reset on the time clock for replacement, or is there somthing like a pcm learning process of the new clean dpf?
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Posting Guru
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From: San Jose, CA
So if I understand correctly, the parameters are specific to the DPF and decided by the PCM/cal
If returning to stock and reinstalling the original DPF, how does the factory flash behave when it starts running for the first time? Do we need to worry it about in terms of the DPF and long term effects? When taking the truck into the dealer for reflashing, like 11B23, does reflashing look just like a return to stock after tuning in terms of what the cal will do when it starts running? Is there any resetting of parameters that need to happen when the dealer reflashes the PCM
Would AutoEnginuity be able to see what's going on?
sorry for the barrage of questions--just trying to understand what all is involved so I don't screw something up later.
If returning to stock and reinstalling the original DPF, how does the factory flash behave when it starts running for the first time? Do we need to worry it about in terms of the DPF and long term effects? When taking the truck into the dealer for reflashing, like 11B23, does reflashing look just like a return to stock after tuning in terms of what the cal will do when it starts running? Is there any resetting of parameters that need to happen when the dealer reflashes the PCM
Would AutoEnginuity be able to see what's going on?
sorry for the barrage of questions--just trying to understand what all is involved so I don't screw something up later.
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