Slow regens and output temp much higher than imput

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antmrt
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Joined: Sun Sep 15, 2024 8:15 pm

Slow regens and output temp much higher than imput

Post by antmrt » Sun Sep 15, 2024 9:38 pm

Thanks for the app it is excellent, my 1,6tdi cayc regens every 300 miles the differential pressure always seems good so calculated soot starts the regen after 21g , the regens are long my last one taking 40 miles and i have to head to an a road with a steep section to get the soot reducing quickly.
so my first question is reasons why its so slow and also the output temps are higher than the inputs ( but similar before starting engine ) and when i look at other peoples screenshots the output temp is lower ,thanks in advance https://i.ibb.co/s9hYCyK/Screenshot-202 ... 3b3817.jpg

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admin
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Re: Slow regens and output temp much higher than imput

Post by admin » Fri Sep 20, 2024 8:17 am

I see your maximum values that seem correct, the input is 680° and the output is 626°. This means that during the regeneration, the temperatures reach the correct values.
The input temp depends mainly on the injected fuel quantity because post injections are a percentage of the main injection, so if the main is low (engine at idle or accelerator pedal released) also them are slow and the temperature can't reach the target value.
If you drive with frequent releases of accelerator pedal, the temperature can't increase so much and consequently the regen duration is higher. Is this your case?
If you log a full regeneration, we can analyze better what happens.

antmrt
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Joined: Sun Sep 15, 2024 8:15 pm

Re: Slow regens and output temp much higher than imput

Post by antmrt » Fri Sep 20, 2024 6:01 pm

ah it says334 input and 519 output on my link if i have done it right , did another regen today and it does seem to struggle to keep the temps high although the temps seemed more even this time ,if i slow to a stop below 8 grams it will be satisfied with that and end regen ,i will try and get a log ,thanks

antmrt
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Joined: Sun Sep 15, 2024 8:15 pm

Re: Slow regens and output temp much higher than imput

Post by antmrt » Fri Sep 27, 2024 2:55 pm

Well you are right about me realising the throttle and slow regens , done one today and it went from 21 g to 5 g in 18 mile as I kept the throttle constant without overruns the input temp maxed at about 640 I think , haven't done a log yet
Again this was calculated soot setting off regen as my diff pressure was only 4 on idle , would be great if I could change the algorithm to give me longer between regents but did I read it's milage related ?
Btw standard BP fuel and ultimate seems the same as regards mileage gaps (around 300 miles)

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Re: Slow regens and output temp much higher than imput

Post by admin » Tue Oct 01, 2024 9:48 am

Many factors concurr to increase/decrease the mileage between regens. The most important value the ECU uses is the differential pressure, but the DPF filling speed depends mainly on the driving style and consequently on the gas temperature.
Driving in highway at constant high speed allows high gas temperature and low soot accumulation because it burns with so called "passive regeneration".
Driving in town with frequent releases of accelerator pedal doesn't allow high gas temperature so the soot accumulation is higher.

Moreover thera are also other factors like fuel quality, ambient temperature and dpf system efficiancy, but, in my personal opinion and based on my experiences, those are less relevant than the driving style.

antmrt
Posts: 5
Joined: Sun Sep 15, 2024 8:15 pm

Re: Slow regens and output temp much higher than imput

Post by antmrt » Sun Nov 17, 2024 10:05 am

it doesn't affect my milage too much between regens however i drive tbh i have a b road 17 mile each way trip to work ,my hottest exhaust temp is maybe 250c up a long hill , when i drove up to Yorkshire (340 miles) it only did a passive regen once for a few seconds then still did it around 300 miles. my car started a regen as always the other day at 21 grams as always but i had to interrupt it and it crept up to 21.7 (calculated) so i set off down the A30 yesterday and it did it in maybe 16 miles going to 4.6 grams , i always have to be carefull when it gets under 8 grams as backing off the throttle down hill can make it finish the regen.
anyway thanks again for the app i set my trip meter after each regen and forget about it until 300 miles ,probably 340 miles next time .
it is regening so much better now on BP standard though than BP ultimate the gaps are the same but up the temps and time are vastly improved

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