Jump in Calculated Soot Mass

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Wilts01
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Joined: Mon Mar 02, 2020 10:07 pm

Jump in Calculated Soot Mass

Post by Wilts01 » Mon Mar 02, 2020 10:16 pm

I have a 2011 Seat Alhambra with a CFFB engine. Recently it has been constantly trying to regenerate - or I think so since the engine fan goes to full speed for 5mins nearly every time I switch it off. Sadly the local dealer doesn't believe me so I am trying to get some evidence.

Tonight, on my usual 10 mile drive home, I set up a recording from cold. I got the attached plots for Soot Mass Calculated and Measured (plus differential pressure) - X-axis is time in seconds.
Journey Home 2020_03_02.png
Is this jump in the calculated value normal? I think that the red "regen pending" indicator came on at the same time but cannot be certain (as an aside, is this logged?).

Pointers appreciated!

Thanks

Paul

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admin
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Re: Jump in Calculated Soot Mass

Post by admin » Tue Mar 03, 2020 11:48 am

I've seen similar step when the "mileage since last regeneration" reached the maximum acceptable value. In fact, one of the protection of the DPF system is the limiting of the maximum mileage between regenerations to prevent the risk of fire in case of failure of some sensor.
Limiting the mileage, the soot mass in the filter can't reach risky values in any case.

In your case, you should understand if the mileage since last regen (this parameter is present in the app) is near 8-900 km, in this case it's normal, otherwise it's possible you have some fault the DPF system. The differential pressure sensor is probably the first you should check, because its failure happens very often.

Wilts01
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Joined: Mon Mar 02, 2020 10:07 pm

Re: Jump in Calculated Soot Mass

Post by Wilts01 » Tue Mar 03, 2020 11:58 am

Thanks. The distance since last regen is being reported as less than 30km. So sounds like a Sensor issue then

Thanks

Paul

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Re: Jump in Calculated Soot Mass

Post by admin » Wed Mar 04, 2020 9:01 am

Differential pressure value is available for your engine in the app, but it's not so easy to understand if the values your read are ok. You should ask to someone who own the same engine or with an expert about the DPF system.
Moreover, the diff. pressure sensor couldn't be the cause of this failure.

Wilts01
Posts: 3
Joined: Mon Mar 02, 2020 10:07 pm

Re: Jump in Calculated Soot Mass

Post by Wilts01 » Wed Mar 04, 2020 11:20 am

Thanks- I’ll ask a bit wider afield now I have the data. What I have found is that the measured value goes down dramatically if I sit on tick-over with regen happening event though the differential pressure is unchanged.

Anyway thanks again for developing such a useful app

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