Hello everyone.

 

I think there might be a problem with my DPF system. It starts a regen almost every time I turn on the car. (I'm noticing that by increased revs, starts stop off due to "engine must be running"). My questions is, has the dpf reached it's end of life? Or is there a faulty differential pressure sensor or anything else? I've attached a screenshot from VAG DPF. I think that the differential pressure is way too high. (Car was idling)

What sort of driving have yo been doing? and how many miles has the car done?

12 minutes ago, MarkyG82 said:

What sort of driving have yo been doing? and how many miles has the car done?

191,278 Km by looking at the DPF data  so certainly within end of life 

op-
Oil ash residue is pretty high but not full, I would suggest taking out for 20-30 miles keeping revs over 2500 also bang some DPF cleaner in -  failing that you're looking at removing for chemical clean or replacement 

Oh yes.  Missed that.  Not familiar with the dpf app so missed it.

 

With that sort of mileage and age it should be fine to give it a good blast as you say.

Short trips around the city during the week, and a highway run in the weekend ( ~150km ). The thing that concerns me is that even after the highway run, the behavior is the same. 

Is chemical cleaning any good? I've been considering that. 

Also, I'm not driving it like a granny. Whenever the road permits it, I use the sport mode. 

short trips kill DPF's 

yeah that's because it's getting full it will regen more and more often and eventually keep regenning constantly until the DPF light comes on and it needs either chem clean or replacing. 

 

essentially soot builds - regen, soot burnt off and  % ash left behind im not 100% on the g / ML quantity before it requires outside intervention.

 

get some DPF cleaner and put that in along with good fuel and give it a blast like redline in all gears then drop it into 4/5 and keep the revs over 2.5K for at least 5 miles if this doesn't stop the regen then you are looking at the options I advised.

 

cleaning does remove the some ash and is cheaper than replacement but it's not like starting with a new one but you might say get another 20K out of it 

I guess it depends on how long you plan to keep it.  Long term? Get the dpf replaced.  Not so long term? Get it cleaned.  Maybe even consider a replacement exhaust with high flow dpf or even removal if you country allows?

I was thinking about replacing it when it reaches ariund the 80% ash mark. Removal is out of the question for me. 

Also, I think I might have found the culprit after hooking VCDS in.

 

It's very likely that the measured value doesn't drop enough and it quickly rises to the 20ish grams and that triggers the regen. What I'm seeing in the VAG Dpf app is only the calculated value.

I'll try doing a forced regen on the highway and it'll probably sort itself out.

See where the measured goes after a regen( you can set VagDpf for group 0) and then see how fast it fills up. 

Had the same problem so questions are:

- how much oil used for 1000km 

- injector state

- lambda sensor changed ? You might have 2

 

I changed 2 and 3 and it was fixed. For most it is number 1 the cause.

 

 

 

 

27 minutes ago, alextz said:

See where the measured goes after a regen( you can set VagDpf for group 0) and then see how fast it fills up. 

Had the same problem so questions are:

- how much oil used for 1000km 

- injector state

- lambda sensor changed ? You might have 2

 

I changed 2 and 3 and it was fixed. For most it is number 1 the cause.

 

 

 

 

Thanks for the suggestions.

I have a few questions though. How do I set vag dpf for group 0? How do I see the injector state on uds protocol? ( I'm used to groups readings in vcds ).

How can I check if the lambda is faulty? There are no errors.

Thanks

For injector state the software does not show the actual state. You need to do return test or extract them and test them on a machine.

Also the lambda can be tested by oscilloscope. 

 

Go in VagDpf and look in setting for group set to auto and change it to group 0.

So I've watched soot mass measured. It went from 16g to 24g in less than 2km. So I think this might be the problem. Any ideea what actually 'measures' the soot mass measured?

It is a calculation based on pressure sensor/MAF/temp sensors on the load of the DPF. 

Either one of these sensors is bad or you have a really bad smoking car.(this was my case). Is the car tuned?

 

Edited 1 February, 20215 yr by alextz

So I've got some updates. 

Today I took the car for a longer run. Shortly after I started, of course the soot mass measured spiked to 24g and triggered an active regen. 

While driving, the soot mass calculated dropped to about 1g. The soot mass measured didn't drop A SINGLE GRAM while driving, even though the EGT was around 610 deg C. As soon as I stopped, in about of 4-5 min, the soot mass measured went from 24g to nearly 5g. 

This makes me think it's a faulty sensor, even though it didn't threw any errors. Also, the soot mass measured never goes up by even a milligram while idling, in contrast to soot mass calculated. If the engine would be running for, let's say 30min, there would be no change in soot mass measured. 

Any thoughts on this?

 

I'll keep this post updated.

Soot mass measured does not increase while idling. That is normal behaviour.

But the fact that it's not dropping while driving, even while regenerating? And then, when i stop the car ( idle ) it completes the regen in less than 5 min. I don't think that's actually happening.

No that is not normal.

Measured should drop faster than calculated and actually get to a negative value.

 

Just do a forced service regen from VCDS and see the values after.

I've added a screenshot showing the soot calculated trend, and soot measured. One going down, one going up. Quite funny.

 

The service regen for this model is stationary or while driving? From what I've read in ross tech, for cars with UDS protocol only stationary is possible.

Stationary.

 

Did you check injector corrections ? I see that the sensors look ok at a first glance.

 

Las sw version for this engine is 8151.

Edited 2 February, 20215 yr by alextz

19 hours ago, BogdanB said:

I've added a screenshot showing the soot calculated trend, and soot measured. One going down, one going up. Quite funny.

 

The service regen for this model is stationary or while driving? From what I've read in ross tech, for cars with UDS protocol only stationary is possible.

Look at the DPF gas temperature & Post Injection 2 & 3, it's trying to do a regen now, even though is says under " Distance Since Last Regen 11Km " so just finished a regen.

 

The output gas temperature is lower than input gas temp so nothing is in the DPF to be burnt.

 

The DPF Differential Pressure ( bottom right box ) shows 226 which is very high if the engine was just ticking over.

 

I would guess that your DPF differential pressure sensor is probably faulty & giving out incorrect data.

20 hours ago, alextz said:

Stationary.

 

Did you check injector corrections ? I see that the sensors look ok at a first glance.

 

Las sw version for this engine is 8151.

Is this what you are refering to?

1 hour ago, PipH said:

Look at the DPF gas temperature & Post Injection 2 & 3, it's trying to do a regen now, even though is says under " Distance Since Last Regen 11Km " so just finished a regen.

 

The output gas temperature is lower than input gas temp so nothing is in the DPF to be burnt.

 

The DPF Differential Pressure ( bottom right box ) shows 226 which is very high if the engine was just ticking over.

 

I would guess that your DPF differential pressure sensor is probably faulty & giving out incorrect data.

That was my impression too. At idle it shows around 36 hPa. As soon as I start accelerating it ranges from 100 to 350-400 hPa.

And it always tries to do an active regen. And the fact that while driving, during an active regen the soot mass measured wouldn't drop(soot mass calculated correctly goes to around 1g), that made me think it's a faulty sensor. But I can't guess which one. 

Yes. Is that taken on idle with normal operating temperature and no load ?

 

If yes your injectors are not OK or worse one of the cylinders is not up to the others so ECU is compensating. 

 

At 163k km I had a 7-8 hPA after a regen at idle. You can check the sensor fast : with power on/ ignition off sensor should show around -2 to +2 hPA. 

Edited 7 February, 20215 yr by alextz

Engine off.

 

 

Engine on idle

 

And sometimes it's even higher on idle. Does this indicate a clogged filter that can't properly regen? 

 

The thing that grinds me is that it will always stay on active regen, even on highway. I've had close to 0 soot mass calculated, and the soot mass measured wouldn't drop.

And I'm guessing it was obvious that there wasn't any combustion in the DPF since the Input Gas Temp. was at around 600+ and the output temp was in the low 500's. 

 

What could actually be causing this high pressure? The ash? Should I just get the dpf manually cleaned?

 

And why is the mass measured rising so fast, since yours was negative even at around 8hpa ? (for example 9g to 24g in a few min and the calculated one barely moves).

The engine is very responsive, doesn't feel like one with a clogged dpf. 

 

 

Change the pressure sensor with a known working one and adapt it. Drive around 30km to see if anything changes.

The fact that temp sensors seem to work OK and pressure sensore will be tested leads to -> clogged DPF or lambda probe issue.

 

I would get the car to a good diesel service and let them try at their expense.

 

Later edit: if DPF is clogged at ~200k km the issue that lead to this need to be found. Poor software/oil consumption/bad injectors like you have on number 2.

Edited 10 February, 20215 yr by alextz

So, update on the situation.

I had my DPF manually cleaned and that seemed to solve to issue so far ( hadn't driven the car only about 100km).

The soot mass measured doesn't go up anymore, and I've even had a passive regen for the first time ( yay).

In about 50km the soot mass calculated only went up by about 2g. 

 

The people that cleaned the DPF said that it looks like there were a lot of interrupted regens from the previous owner by the looks of it and that's what it caused it to clog. 

Edited 5 March, 20215 yr by BogdanB