Emissions remap

[chimaera]

58 minutes ago, linni said:

Today did regen at about 50%.

Urban cycle boosts soot production up. Just urban cycle I guess 250 km is maximum we can reach.

From the other side, app graphics show almost constant burning process is going on in filter all the time. During hard accelerations soot mass even drops a little.

So, keep agressive driving style and your DPF never fails!

 

The car will do continuous passive regeneration rather than active as much as possible. So if you're driving long distances a lot, your DPF is never going to fill up much because it's always being cleaned. This also helps keep NOx emissions down, since the NOx in the exhaust is used to oxidise the soot.

In urban driving, the distances are shorter and often the car may not reach operating temperature very much, so passive regeneration is not possible. In this case it will actively regenerate to clear the filter when the differential pressure across the filter becomes too great.

[matnrach]

I think it depends on what temp the DPF is , if it passively regenerates . As I drive at 70-72mph I don't see any passive regeneration.

Maybe I will go a little faster and see it if regenerates. I guess it depends on the temperature so 70-72 up a hill maybe OK.

I will have to pay more attention to the app when on cruise

[linni]

Speed is not important here. Full version of app includes also DPF in and out temperatures. Regen at 600 celsius, passive at around 380 celsius. It does passive burning even at city speeds.

[matnrach]

I have the full app and I certainly don't see 380 around town . Last time I looked I was about 340deg on the motorway and the temp was speed and load (throttle) dependent

Around town I think it cools right off to 200 or less from memory

[linni]

Not sure about city temperature, but it did definitely passive regen when I was driving around the town today.

 

[chimaera]

57 minutes ago, linni said:

It does passive burning even at city speeds.

 

It can if you've spent long enough driving that the car is able to reach and maintain operating temperature. My earlier comment is that this is less likely in urban driving compared to longer distance driving outside of the city.

[matnrach]

Going on a long motorway run tomorrow so will look at temps. I wonder why the Torque APP does not have  a VAG plug in as you can log everything with that and it would be much simpler

[Razzertrevor]

What information does the torque app give you

[matnrach]

18 minutes ago, Razzertrevor said:

What information does the torque app give you

Huge amounts but not DPF info .  I believe some other cars have specific plug ins which does display DPF data but not VAG as far as I am aware

[Razzertrevor]

Can it be used to reset service milage

[matnrach]

I dont think so but you can see error codes and clear them as well as log loads of data 

[matnrach]

On 09/11/2017 at 16:47, matnrach said:

Going on a long motorway run tomorrow so will look at temps. I wonder why the Torque APP does not have  a VAG plug in as you can log everything with that and it would be much simpler

During the run today I saw about 300deg at 70mph when I could do it as the traffic was quite heavy.

Interestingly looking back at the data from the previous regen , it was at 62% not 50%????

Also as the speed was mostly between 60-70mph without many accelerations my average for the journey was 74mpg! I never even got close to that in my 1.6HDI Citroen 

 

[Razzertrevor]

I thought I was doing well getting 60 mpg 

[jafo]

@Steviejay beside higher idle rpm you will also smell burnt rubber

[linni]

Noticed very strange thing today.

Was doing motorway drive, constant speed 100 km/h at cruise control. Suddenly it started: 1,5 sec fuel injection on, 1,5 sec fuel injection off.  Was even more sharp when switched the gear down to 5th, the car felt Just like shagging

Switched DPF app on, of course it was doing regen.

Does it really cut off injectors to engine when injecting fuel to DPF?

[Breezy_Pete]

As far as I'm aware, the DPF doesn't have its own injector(s). Fuel for active regeneration comes from the engine injectors (dispensed later than usual).

[chimaera]

The fuel used for regeneration on the 2.0 engine is supplied by a late injection event during the combustion cycle: it injects during the exhaust stroke so that unburned fuel exits with the exhaust gases. This fuel is then oxidised by NOx and excess O2 in the DPF to burn off accumulated soot.

[Razzertrevor]

I was on the motorway when my regen accurd if it wasn't for the app I wouldn't have known 

[stever750]

On 24/10/2017 at 22:20, chimaera said:

It doesn't work like that. The ECU measures pressure differential across the DPF and when it reaches a certain level, it initiates an active regeneration. This will be at or near 100 % loading of the DPF. The ECU can't directly measure the soot mass accumulated in the filter, it calculates an estimate based on differential pressure.

 

If an active regeneration is interrupted by engine shut down, it'll try again the next time the car is used. If it's repeatedly interrupted then you will eventually get an orange DPF warning light on the dash, and a warning on the MFD to go for a regeneration drive (this is outlined in the manual). If you don't do this, you'll eventually end up with a red DPF warning light and an instruction to drive to your dealer, where you may well be told the DPF is toast and needs replacing.

 

An additional consequence of repeated interruption of regens is that you'll end up with fuel in the engine oil: during active regeneration, extra fuel is injected near the end of the combustion cycle to flow through to the DPF to help it light off. If you interrupt regeneration, this fuel stays in the cylinder and drains down into the sump after shutdown.

 

As much as possible the engine will try to regenerate passively during normal operation. This usually happens on longer runs where the engine can get fully up to temperature and stay there for long periods. Under these conditions, the soot in the DPF is constantly being burned off without any change in engine operation.

 

Passive regeneration is part of the NOx management strategy employed in these engines: it's actually NOx that's used to burn off the accumulated soot, converting the soot to CO2 and the NOx to molecular nitrogen gas.

Interesting post. Does the oil contamination only happen if you interrupt the regen part way through? If the regen is completed with the engine running, does it also contaminate the oil? If so, how, what is the path? 

[stever750]

On 09/11/2017 at 14:55, linni said:

Speed is not important here. Full version of app includes also DPF in and out temperatures. Regen at 600 celsius, passive at around 380 celsius. It does passive burning even at city speeds.

I've been using the app open for last 1000 miles, I don't drive gently.but max temp at dpf I've seen is 400degC or so and that was full throttle up a long steep hill with 3 passengers. The soot level was still positive (in the mg/km instant readout) and the soot accumulation was increasing. The only time the soot level drops is during an active regen where the DPF hits 60degC. Even caning my car doesn't get the DPF hot enough to burn off any soot, so I'm not convinced it happens. 

[langers2k]

I've certainly had "soot measured" drop when travelling at a steady 120kph-140kph abroad. I don't think I've seen the "soot calculated" drop unless it's doing a regen.

 

Full throttle will produce more heat but it'll also make more soot which might be why it's not dropping up your hill...

 

As for the oil contamination, I don't think it's much of a worry unless the car is constantly trying to regen and you're interrupting it on every shutdown. Assuming the car is working normally and your driving gives it chance to regen fully, it'll probably be fine.

[stever750]

41 minutes ago, langers2k said:

I've certainly had "soot measured" drop when travelling at a steady 120kph-140kph abroad. I don't think I've seen the "soot calculated" drop unless it's doing a regen.

 

Full throttle will produce more heat but it'll also make more soot which might be why it's not dropping up your hill...

 

As for the oil contamination, I don't think it's much of a worry unless the car is constantly trying to regen and you're interrupting it on every shutdown. Assuming the car is working normally and your driving gives it chance to regen fully, it'll probably be fine.

It's the word probably that concerns me! 

Either a moving regen has little or no dilution effect or it does which is kind of important on a remapped engine. 

Avoiding interrupting a regen by stopping is a given. 

[stever750]

One of the key bits of info on the app are the output of soot in g/km. This is what is driving the soot fill rate and therefore regen frequency. Steady state motorway at 80 ish mine is between 18-25. Stop start traffic and it shoots up as you'd expect. 

 

My oil Ash is high at 16.9g for a car with 40k miles. I suspect that non long life oil and a tuning box have caused that..... 

[langers2k]

I thought the only 'correct' oil spec for DPF based cars was a low SAPS long life oil? If it's not low SAPS it's going to cause you DPF issues.

 

It's normally where you drive and driving style that'll have most effect on DPF life although I doubt a tuning box will improve it.

 

What makes you think ~17g in 40k miles is high? That certainly seems to match what other users have posted previously. I'm not sure what engine you have or what it's max oil ash is but that's probably a DPF lifespan of 160-180k miles which seems reasonable.

 

To put the 'probably' in to context, my car is on ~153k miles so it's done 100's of regens including a good number of interrupted ones. If there was an issue with dilution from normal regens or occasionally interrupting them, I'd expected to have some kind of issue by now. Even more so as the car has only ever been on long life servicing so the oil is swapped every 18k miles.

 

If you're really concerned about it, you could change the oil every 10k or even 5k to keep it fresh. You can even send oil samples off to get tested which will confirm if your engine does have a issue.

 

edit:

Just to add to the oil ash vs mileage point, another member just posted a screenshot showing 20g in 46k miles which is almost identical to 17g in 40k miles:

 

Edited 30 October, 2018 by langers2k

[jafo]