Technical HELP!! Massive clouds of white smoke (mostly) on Regen.

[lycopersicum]

And for comparison here's a successful regen on my van.

 

[Golonko]

Just an update: today I saw two regen attempts during my drive, both with a lot of white smoke. In one of them, the DPF temperature rose to around 800°C, but then dropped down to about 580°C before the regen was interrupted. There’s no clear pattern in pressure or temperature when the regen cuts off — values go up and down but nothing looks extreme.

Eventually, after some steady driving, it completed a full regeneration and soot load dropped from 94% to 16%. So the system is working, but it seems to take a few attempts before it succeeds.

I’ve already replaced the DPF, the differential pressure and temperature sensors, and the DOC (front catalyst was clogged). Injectors have been tested, and EGR was inspected during the engine replacement.

Appreciate all the input — still monitoring!

 

[jackwhoo]

Injectors tested .......by a fully acredited ( by the injector manufacturer) test center?
Did you get different injector coding for each injector back from test centre with each injector?
We're the injectors replaced in the same cylinder that they came out from?

 

[lycopersicum]

800°C sounds extreme to me. Mine goes to 650°C on the flat and occasionally overshoots to 710° at most when going down after a hill. I would think it rather likely that the ECU would interrupt the regen if the temperature went that high.

Did you find out why the DOC got clogged in the first place?

Attached is a PDF from elearn describing the regen process. Some parts are confusing and apparently badly translated from Italian, but you will learn among other things that the regen is a two-stage process involving first getting the catalyst up to temp.

 

[Golonko]

Thanks a lot for the document, I’ll go through it carefully — even with the bad translation!


Regarding the DOC, the front part of it was heavily clogged, so we decided to replace the whole DPF assembly including the DOC. Unfortunately, we couldn’t determine the exact cause, but it might have been due to incomplete regenerations in the past or oil contamination during the engine swap (the engine and injectors were replaced a year ago).


About the temperature: I’ve seen the DPF temp reach 800 °C during regen attempts, but the actual cutoff doesn’t happen at that point — in fact, when the regen cuts off, the temp is around 580 °C. So maybe the peak temperature isn't the trigger after all. I haven’t found a consistent pattern between temp, pressure or speed and the regen interruptions.


Eventually the DPF did regenerate properly after the last trip, and the saturation dropped to 16%. But I’m still trying to understand why so many regen attempts get aborted before that.

 

[Golonko]

Update — electrical reset during regen attempts?


Hi again,
I wanted to add one more detail that I now realize may be very important.


During the failed regeneration attempts, I noticed something unusual: the dashboard behaves as if the ignition was turned off and then quickly back on again. It briefly flashes the normal "check" messages, like when you first turn the key. Then everything resumes as normal.


This doesn’t seem like a normal regen interruption. It feels more like a brief reset or power interruption affecting the ECU or another control unit. However, it only ever happens during regeneration, never during regular driving.


This makes me think it’s not a random wiring or ground issue, but something that triggers specifically under regen conditions — maybe a sensor reading, excessive current draw, or a thermal protection mechanism?


Has anyone else seen this type of behavior? A regen attempt that seems to trigger a quick system reset?


Thanks again for all the help — I’m still trying to get to the bottom of this.

 

[Golonko]

Re: the data, how high does the DPF temperature go before it gets interrupted?

Sorry, because my later answer:
In the interrupted regeneration attempts I recorded, the DPF temperature rose up to around 800°C. However, the actual cutoff didn’t happen at the peak — it occurred when the temperature had already dropped to about 550–580°C, several seconds after the highest point.


So it doesn’t look like the interruption was due to over-temperature. It seems more like a logic or electrical event — possibly a momentary ECU reset or protection trigger, because the dashboard briefly showed the ignition “check” messages, and the OBD data stream dropped momentarily at the same time.


Now the ECU is being reviewed remotely using a Pass-Thru system, and they’re planning to apply official software updates for this engine model. Apparently, the updates are specifically related to DPF regeneration strategy and fuel injection control.


I’ll be testing the vehicle this evening after the update, so I’ll post an update with the results.

 

[Golonko]

We've now gone through three regeneration cycles. They're happening after more than 1,000 km each time. At the beginning of each regen there's a noticeable burst of white smoke for a few seconds, but then the process enters a phase where the temperature rises and falls in cycles — which seems to be part of the normal regeneration behaviour.

It seems that driving gently and steadily (around 2,000 rpm) helps avoid the contact cut-offs we used to experience, and allows the regeneration to complete properly.

Just sharing this in case it helps someone else — for now, it looks like the issue might be resolved.

 

[Golonko]

I wanted to share a recent test that might be useful for others.

During a regeneration today, I initially tried following some advice I’d read to keep the engine around 3,000 rpm to raise the DPF temperature. Shortly after starting the regen at that rpm, I experienced the usual contact cut-off and the regen failed.

A bit later, the ECU started a new regeneration. This time I did it my usual way — keeping the revs steady around 2,000 rpm and driving very gently. The regen completed fully with no cut-off and no fault codes.

In my case, DPF temperatures usually reach around 850 °C (sometimes slightly higher) during regen. It seems that avoiding high rpm makes it much more likely to finish successfully.

 

[theoneandonly]

I wanted to share a recent test that might be useful for others.

During a regeneration today, I initially tried following some advice I’d read to keep the engine around 3,000 rpm to raise the DPF temperature. Shortly after starting the regen at that rpm, I experienced the usual contact cut-off and the regen failed.

A bit later, the ECU started a new regeneration. This time I did it my usual way — keeping the revs steady around 2,000 rpm and driving very gently. The regen completed fully with no cut-off and no fault codes.

In my case, DPF temperatures usually reach around 850 °C (sometimes slightly higher) during regen. It seems that avoiding high rpm makes it much more likely to finish successfully.

Have you got any of the csv files we could look at and have a play.

 

[lycopersicum]

I have also noticed that working the engine harder reduces the regen temp. It looks as if there's a maximum amount of fuel that can be injected and if the power stroke uses more of it there's less available for the regen on the exhaust stroke. Or maybe it's because of the increased exhaust flow.