Hi,

i have a problem with my Octavia dpf regeneration. This sunday i had one longer journey 100km motorways and 50km contry roads and when i get home I noticed that my fan is running so I waited a bit and then stopped engine after 5 mins but fan was still running. 

My normaly drives for work are about 20km long, so next day when i went to work it was trhe same with fans and I noticed that engine is keeped between 900-950 rpm when iddling. 

So I took it to my friend whitch have VCDS and there was no error or anything. 

 

The problem is that regen is triggered allways when i drive the car after about 5 minutes and it never finishes. 

Yesterday i get an VAG DPF app on android phone and bloutooth connector so i can monitor the temperatures and Soot mass. So I went to a trip for about 1,5 hours driving constantly with 3rd gear with about 200-2500 rpm and speed over 60km/h. When I started soot mass was about 6g and after about 2km it simply jumps up to about 26g and the app gets sign that engine is waiting  or running for right conditions. So i drive with 3rd gear and the soot mass starts to drop. After about an hour the yellow dpf icon on dashboard appears. After 1,5 hour it drops to less then 1 gram but regen still wasnt complete. So i stopped the car waited a bit and stopped the car. Then i waited a bit(fan was running) and then started the engine again and go for another ride. After few minutes the soot mass jumps again from less than 1g to 26grams. I rode for about 30 minutes home and the same thing. Soot mass droped fan was still running. This is now happening all the time when i drive the car.

 

Tomorow i will go for a motorway and try to go more than 100km/h(4th, 5th gear 2000-2500rpm) cuz I read somwhere that active regen(out temperatures more than 600°C) occurs only when going over 100km/h.

 

So the question here is:

-how long does it take to finiseh the regen. I read that max time for regen is 25 mins?

-will the motorway drive finaly finished the regen?

-is there any difference if the regen is triggered with VCDS, suggestions do i trigger it or no?

-is there any possibility that any other sensor is faulty and is the cause that regen is allways triggeres?

-how is the soot mass calculated - measured? How is dpf fill percentage calculated?

 

Thank you all for answers

 

 

Not sure about answers to your questions but we sometimes get times when regen doesn't finish properly for a few days. It eventually sorts itself out though.

I did read somewhere some time ago that someone had a laptop connected and monitored the dpf and the optimum engine speed was a steady 1800rpm to 2000rpm for several miles/km to clear the dpf.

Edited 14 April, 201610 yr by FatblokeVRS

There are a bunch of sensors on the DPF to help the ECU calculate the current soot levels.

 

The jump from 1g to 26g sounds strange... Are there any error codes? I'd expect at least one while the yellow DPF symbol is lit.

 

VCDS can force an 'emergency' regen but your car really should be able to regen under normal driving conditions unless there is a problem. More info here: http://wiki.ross-tech.com/wiki/index.php/Diesel_Particle_Filter_Emergency_Regeneration

I've seen this image before. Strange think to me is that regen is starting always when i drive and that it never finishes. There is no Error codes in VCDS. The DPF symbol gets up after 1 hour of regen or something like this and it goes of when i restart motor. 

This jump from 1g to 26g is in this android app and i dont know if it works ok. I'll try this with VCDS and see how it goes.

 

I hope that tomorow when i go to motorway it will finish the regeneration.

Regen shouldn't take an hour. Taken from the manual:

 

Vehicle should be driven at at least 60km/h for engine speeds 1800 - 2500 rpm for 15 minutes in 4th or 5th gear.

I'd say that it's faulty sensor or something like that. Usually these regenerations last like 10 or 15 minutes.

Once I had a strange situation when i saw regeneration happening for ~40 minutes (I usually detect it by fuel consumption increase). After I had certain problems - I guess it was because of poor quality fuel. It's not a daily routine

 

How is soot level calculated? There are sensors before and after DPF. If pressure is even then computer understands that DPF is empty there's free air flow. If there's something in then there is certain difference and that's how it's calculated.

 

 

 

 

Tomorow i will go for a motorway and try to go more than 100km/h(4th, 5th gear 2000-2500rpm) cuz I read somwhere that active regen(out temperatures more than 600°C) occurs only when going over 100km/h.

 

That's not true. Many countries have speed limit 90 km/h so it would mean that you can't legally have a regeneration As the manual says, speed over 60 km/h and revs ~1800-2500.

Edited 14 April, 201610 yr by Jevpls

Another vote here for you having a faulty sensor.

 

Unfortunately a faulty sensor doesn't always result in a fault code which is going to make it difficult to determine which one is at fault.

I logged the temperatures and calculated soot from my journey to work this morning as a reference for you.

 

This is an hours driving, you can see the A-roads, motorway and then town sections of my drive clearly from the EGT. There isn't any regen going on so I'll try and log my next few drives to catch that for you. However you can see the steady rise of calculated soot which is completely different to the 1g-26g jump you described.

Thx all. What program did you use to get this graph?

 

Today ill get VCDS and will check difference between measured and calculated soot..

MVB 108.2 or 241.2: Particle Filter Soot Mass (calculated)
MVB 108.3 or 241.3: Particle Filter Soot Mass (measured)

I used VCDS to create a CSV file containing the logs, I then used excel to open the CSV and convert it to a graph. I would expect any office suite (microsoft office, openoffice, libreoffice, google docs etc) should be able to produce something similar.

 

I didn't plot 'Particle filter; soot mass measured' as it barely changed, it was -0.3 at the start of the log and -0.29 at the end.

Hey all. I used VCDS and "Particle filter; soot mass measured" measurement always show around 25grams. Calculated value is droping to les than 1gram, but it resets after i restart motor. I switched preasure sensor with the one from my brothers octavia(same sensor) and it shows same measurements as mine so there is no fault in preasure sensor. I think regeneration is based on measured value, so my octavia is triggering regeneration always and never finishes it, even if i'm driving for 2 hours.

 

Can there be fault in any other sensor like lambda or temperature sensors. I think that measured value is only depending on preasure sensor? 

 

Is it worth to triger regeneration while standing(http://wiki.ross-tech.com/wiki/index.php/Diesel_Particle_Filter_Emergency_Regeneration) and if no better regeneration while driving?

 

Can there be fault in the computer if it doesnt finish regeneration? maybe it finishes it and then starts it right after again?

 

Is it worth to triger regeneration while standing(http://wiki.ross-tech.com/wiki/index.php/Diesel_Particle_Filter_Emergency_Regeneration) and if no better regeneration while driving?

 

 

You may try but it might not solve the problem. Nobody knows what could happen after that - your car may still think that there is these wonderful 25 grams of soot...

I'd say that searching for "DPF removal" might be the best long term solution

I was looking some measuruements with VCDS and the preassure difference when the car is turned off is 153 hPa? Shouldnt there be less difference. I noticed that "Particle filter; differential pressure; dynamic offset" measurement is -140hPa. Why is this offset so low?

 

Yeah DPF removal costs 400€ and I'm vorried about technical reviwews for registring the cars. 

 

Why the DPF would be bad allready its just half full?

 

 

today I measured my ride from home to work - about 22km, 25minutes. Here is visible that regeneration is happening becouse temperatures are so high.

Your car is definitely doing a regen as the EGT is much higher than mine although I would expect the measured soot mass to drop at a similar rate to the calculated soot mass. Of course I've not seen a regen take place so I could be wrong and the delay between measured and calculated might be normal...

 

The pressure sensor might need adapting to the car as you've switched them over - just a guess but might be worth considering given new sensors would need adapting to the car. When you had the pressure sensor off did you check both pipes to the DPF are clear?

 

I've been logging various parameters for every drive I've done for the last few days.

- 'Particle filter; difference pressure' is around -1hPa before starting the engine and then anything up to 200hPa while running

- 'Particle filter; offset for differential press.' is always 1hPa

- 'Particle filter; differential pressure; dynamic offset' varies between -1hPa and 4hPa

- 'Particle filter differential press. sensor; uncond. voltage' is between 1000 and 1900 (I assume this is mV)

- Both measured and calculated soot mass are increasing as expected

 

I'm hoping to get enough soot mass for the car to attempt a regen as that'll give you a better idea of what normal should look like.

 

New graph attached:

Yeah, it doing regen, Today I'll blow in the hose from dpf as it sais in replace instructions and try adaptation on this sensor if there will be any change. Strange to me is that dynamic offset is so low. I only have one hose connected to DPF and the other is just 5cm long and connected nowhere(same on my brothers Octavia). Mk2 motors have G505 sensor and it is only connected to DPF with one hose(http://workshop-manuals.com/skoda/octavia-mk2/power_unit/2.0/81;_103;_125_kw_tdi_cr_engine_(2nd_generation)/exhaust_system/removing_and_installing_parts_of_the_exhaust_system/pre-exhaust_pipe_summary_of_components/summary_of_components_for_enigne_with_identification_characters_cfhc_cfhf/).

After adaptation ill try to triger regen from vcds.

Hey all.

 

Today i measured calculated and measured soot mas from work to home. I noticed that measured is only droping while stationary iddling, so when i get home i waited and measured soot mass droped to 6 grams and then finnaly after more than 1 week the regen was finished and car iddling was droped to 750rpm. Now i will wait for car to cool down and will go for another drive. 

 

Looks like its ok now. I've gone for another ride after regen finished and it looks like its ok now. Measured value is still droping but the car isn't doing regens anymore.

I will drive for a week and report if i'll figure out something new and how soot mass will raise.

 

I think that Octavia has gone to stationary regen and it simply didnt finished, but i don't know why.

I hope that my DPF will be ok for some time now..

 

Thank you all for helping tips.