[sbm]

Originally Posted by arj2695

The phenomenon of fuel mixing with oil is called Oil Dilution. It is perfectly fine until the viscosity of the oil is not going below the specified limit (how much oil can get diluted is tested and found out by OE)

It is perfectly normal for Diesel to mix with engine oil. The method employed in XUV 700 to remove soot from the DPF is by injecting diesel during the exhaust stroke where the fuel (HC) with go to Oxidation Catalyst and gets oxidized, which increases the temperature in DPF, which will burn the soot particles accumulated there. As diesel is injected during the exhaust stroke, there is a possibility for the fuel to mix with the oil.

But, there are some vehicles, were a separate injector is used which directly injected fuel onto the exhaust gas (HC Doser), in this case fuel mixing with the oil is very limited.

I am not sure how the dip-stick is calibrated (designed) to take this phenomenon into account.

Please do PM me if you have any other questions regarding this.

Thanks.

The main issue right now is frequent clogging of the DPF. It has clogged twice in the last 200 km, whereas this has never happened before in 17800 km. I think your PM is not activated; please activate it so that I can text you.

[Gannu_1]

Originally Posted by arj2695

Please do PM me if you have any other questions regarding this.

Guys, please post on the forum instead of private messages so it helps others as well. Unless you’re sharing details like your contact number or mail.

[arj2695]

Originally Posted by sbm

The main issue right now is frequent clogging of the DPF. It has clogged twice in the last 200 km, whereas this has never happened before in 17800 km. I think your PM is not activated; please activate it so that I can text you.

I don't think I can activate PM as I am newbie.

This issue of Oil Dilution is higher in MT vehicles as compared to AT vehicles. One main reason for this is that lower engine speed in Idle. Whereas in AT the engine speed is comparatively higher as it is needed to run the torque-converter.

If your driving route has more idle zone (bumper to bumper traffic, leaving the vehicle idle etc.) or the average vehicle speed is less than 25kph, the regeneration interval could be lower. In such cases, multiple regen would be triggered by EMS within every 150-200 km. This could lead to mixing fuel with oil and lead to Oil dilution. Also, in such low vehicle speeds, if you are in higher gear, the engine would not be able to produce sufficient temperature for completing the regeneration with in the time frame and hence would be cut-off and soot might not have completely burned.

These are just possibilities for higher oil dilution and lower RI. I am not sure how your driving pattern is, but please rise this issue with the Mahindra service team. Higher Oil dilution could lead to damage of internal engine components mainly Connecting Rod.

Originally Posted by Gannu_1

Guys, please post on the forum instead of private messages so it helps others as well. Unless you’re sharing details like your contact number or mail.

Sure, I just wanted to connect with his privately to know his driving pattern and a little more about the vehicle so that I could guide him better.

[sbm]

Originally Posted by sbm

1)I live in Bokaro steel city which is an industrial town with the the Bokaro Steel Plant at its heart. Dense traffic is rare except in few areas which I encounter once or twice a month.
2)The roads here are pretty wide and traffic density is such that one can maintain speeds between 40- 50kmph during most of the commute to my workplace.
3) I use my car around 10 times a month to go office as we have formed a car pool and that also means that during most of this trips, there are 3-4 people in the car.
4) The office trip is 10km each way with speeds ranging 40-60kmph during the first 5kms and during the next 5kms there is a speed limit so speed has to be below 40kmph. Total trip duration is 15-20min.
5) Every month we try to take a day trip to a nearby location at a distance of 25-30km during which speeds can reach 80kmph and seldom we encounter dense traffic.
6) I also use my car for daily chores like buying grocerries etc almost everday.
7) 3-4 times an year, we visit our home town in uttar pradesh 550km from here going through 250km on NH2 and then on Bihar state highways and UP state highways.
.

Originally Posted by arj2695

I don't think I can activate PM as I am newbie.

This issue of Oil Dilution is higher in MT vehicles as compared to AT vehicles. One main reason for this is that lower engine speed in Idle. Whereas in AT the engine speed is comparatively higher as it is needed to run the torque-converter.

If your driving route has more idle zone (bumper to bumper traffic, leaving the vehicle idle etc.) or the average.....

Long post alert. Thanks for your indulgence.

Regarding oil dilution, as you have explained and as I also learned, it happens mainly due to the regen process. Frequently aborted regen due to short trips dumps more diesel in the engine oil.When the technicians drained engine oil from my car, they found 7 litres, i.e., 1 litre in excess. I verified from multiple sources in the Mahindra dealer network that this much mixing is permissible. In fact, Mahindra has recommended changing engine oil at 10 km instead of 20 km when driving in city conditions. So I have decided to regularly change the oil at 10K now.
Regarding DPF clogging never faced DPF clogging during 17800km and 1 year of ownership. I have described my driving pattern in the above-quoted post.

It was after this EMS flashing that I faced two warnings. Another Bhpian and two more Facebook group users have also reported the same. I took the car to the service centre yesterday, and the following happened:

1) They outright denied that it was happening due to the EMS software update. Note that this has never happened before with the same driving pattern.

2) They checked the soot mass, and it came to 10 g collected in 36km. Last time, there were 19g collected in 168km. They concluded that the car is generating excess soot, and they'll have to check the fuel system, air intake system, EGR, turbo, etc. At first I didn't allow them to take apart my car as I knew they would create more problems in the process, but later I allowed them to check the air filter, diesel filter, turbo, and throttle body. I have attached photos here. They said that the air filter and diesel filter choked, and that would also cause excessive soot generation. I agreed to change those parts as the 20K service is coming up anyway.

3) Regarding diesel quality, they said that diesel quality is fine, but it's not BS6 diesel. That is a surprise in itself, as the last refill was from my regular diesel bunk, and it has never caused any issues before. I have attached a picture of the diesel sample they took.All this time, they denied that a bad EMS configuration might be responsible for excess soot generation.Please note that the only time I had to refill at an unknown diesel pump was during my Nepal trip last month. That was two refills ago.After doing all this, they asked me to use the car to see if DPF warnings were coming now or not.

Now, my doubt in all this fiasco is:
1) Why did this all start just after EMS flashed? Everything else was the same as before, and I never faced any issues.

2) There is a possibility that Mahindra has tweaked regeneration parameters to reduce the number of aborted regeneration cycles. Even if it is so, is it normal to receive a DPF warning every 150km? I mean, the car is not even trying to perform regen during normal running and is straight away asking the user to perform it.

3) Do you think that the choked(?) air filter, diesel filter, and diesel quality might be causing excess soot generation and it might just be a coincidence and the EMS thing has nothing to do with this all?

I might be overanalyzing all this, but I can't shake this off as the car was fine until now, and I can't help but blame the software update for all this.

[arj2695]

Originally Posted by sbm

1) They outright denied that it was happening due to the EMS software update. Note that this has never happened before with the same driving pattern.

As I had experience working with EMS software, any modification done by OE would have been validated before using them in a customer vehicle. But, this is a possibility. Any anomaly in software could cause unexpected behavior, not limited to DPF clogging.

Originally Posted by sbm

2) They checked the soot mass, and it came to 10 g collected in 36km. Last time, there were 19g collected in 168km. They concluded that the car is generating excess soot, and they'll have to check the fuel system, air intake system, EGR, turbo, etc. At first I didn't allow them to take apart my car as I knew they would create more problems in the process, but later I allowed them to check the air filter, diesel filter, turbo, and throttle body. I have attached photos here. They said that the air filter and diesel filter choked, and that would also cause excessive soot generation. I agreed to change those parts as the 20K service is coming up anyway.

10g of soot accumulation within 36km is really high. Also, 19g for 168km is also high. For XUV, if you are driving in city, the soot accumulation is approximately 22-24g for every 300 or so km. As mentioned in your post, this could happen because of choked airpath. If this happens, it could lead to higher EGR flow and produce more soot. Also, if Diesel filter is choked, it could cause problem with combustion.

Originally Posted by sbm

3) Regarding diesel quality, they said that diesel quality is fine, but it's not BS6 diesel. That is a surprise in itself, as the last refill was from my regular diesel bunk, and it has never caused any issues before. I have attached a picture of the diesel sample they took.All this time, they denied that a bad EMS configuration might be responsible for excess soot generation.Please note that the only time I had to refill at an unknown diesel pump was during my Nepal trip last month. That was two refills ago.After doing all this, they asked me to use the car to see if DPF warnings were coming now or not.

Not sure how they say it is not BS6 diesel. Can you ask them to get a report of the same. I am sure Research center at Mahindra has facility for inspecting Diesel quality. BS6 has been there for the past three years or so.

Originally Posted by sbm

Now, my doubt in all this fiasco is:
1) Why did this all start just after EMS flashed? Everything else was the same as before, and I never faced any issues.

2) There is a possibility that Mahindra has tweaked regeneration parameters to reduce the number of aborted regeneration cycles. Even if it is so, is it normal to receive a DPF warning every 150km? I mean, the car is not even trying to perform regen during normal running and is straight away asking the user to perform it.

3) Do you think that the choked(?) air filter, diesel filter, and diesel quality might be causing excess soot generation and it might just be a coincidence and the EMS thing has nothing to do with this all?

I might be overanalyzing all this, but I can't shake this off as the car was fine until now, and I can't help but blame the software update for all this.

Now, the answer why this happened could be because of many other reasons, it could be just a coincidence that all start right after EMS software update. But we cannot rule out EMS until we can prove otherwise.

It is not normal to get DPF clogging warning every 150 km. DPF warning would only come up if the regeneration has not happen even after reaching the maximum soot limit.

As they have replaced the filters, please keep an eye on how the vehicle performs. If it is still performing the same, then software might be the culprit. But, it would be hard to make service team believe it. Please do escalate to higher MnM team.

[sbm]

Originally Posted by arj2695

...
It is not normal to get DPF clogging warning every 150 km. DPF warning would only come up if the regeneration has not happen even after reaching the maximum soot limit.

As they have replaced the filters, please keep an eye on how the vehicle performs. If it is still performing the same, then software might be the culprit. But, it would be hard to make service team believe it. Please do escalate to higher MnM team.

Update at 22600kms

As mentioned in my previous posts, my XUV 700 diesel MT (as well as many others) started receiving DPF clogged warnings every 150–160 km after an EMS update. I was really worried at the beginning and ran to the service center for a solution, but they were unable to offer any. They checked certain things and let me off. As of now, the warnings keep coming at the same interval, but I am less intimated by them now. I have seen that the car starts giving signs that it's trying to perform regen, as at around 2000 rpm, fuel supply feels like getting interrupted, which I believe is happening due to the post-injection of diesel. If I am unable to keep the car running for 5–10 km at that time, it tries again in the next cycle. Even if the next cycle is short and regen is terminated, the REGEN needed warning comes on. I then drive the car at 2k rpm for around 10–15 minutes, and the warning goes away.
I now recall that even before the said EMS update, this interruption in fuel supply was felt sometimes, but I used to think that it was a software glitch and didn't care about it much. I believe the car was completing regeneration in multiple attempts back then, rather than throwing up a warning after two or three failed attempts. Also, whenever I have done a fairly long trip of this duration, the warning does not come for another 100–150 km.
I have now accepted that it's due to the usage pattern that these warnings are coming frequently, and since the vehicle is running fine, I have let the issue take a backseat, though I will get the car checked at a bigger dealership once the car completes 25000km.
@arj2695 Please comment on my observations. Also, I have another concern in mind. Since my diesel car is being used primarily for short trips, I am thinking of performing preventive maintenance earlier and changing the oil every 5000 km, as frequent regeneration will cause oil dilution with diesel. As per my understanding, I should get EGR cleaning done more frequently. Can you guide me on this aspect, i.e., how to maintain diesel engines if used in short cycles?
I would also like to connect through mail. Can you please allow email contact in your profile if you don't mind? Thanks

[arj2695]

Originally Posted by sbm

Update at 22600kms

As mentioned in my previous posts, my XUV 700 diesel MT (as well as many others) started receiving DPF clogged warnings every 150–160 km after an EMS update.

Hello there, sorry that it took a very long time to respond.

From my experience, the 150-160km interval between two subsequent regeneration is rather low. If your average velocity is always less than 25kph, then there is a high possibility for such a low interval.
One of the reasons for this is that sufficient temperature would not be available for completing a successful regeneration which could prolong a regeneration (which could cause oil dilution) and also limit the actual soot burnt off from the system. This causes the next interval to be reduced as well.

About you being able to feel interruption in fuel supply is not usual. In general, the difference between when in regeneration and when not should be very minimal (slight variation in engine note and also mild perceptible heat near the Pedal area). So, I am rather confused when you say that you can fuel supply interruption.

Originally Posted by sbm

@arj2695 Please comment on my observations. Also, I have another concern in mind. Since my diesel car is being used primarily for short trips, I am thinking of performing preventive maintenance earlier and changing the oil every 5000 km, as fr..

As you are consistently getting low intervals, it is best to keep an eye on the Oil level. As dilution increases, the lubrication effect of the oil will decrease drastically. It would be a wise idea to check and refill rather than just changing it for every 5000km. I vaguely remember that the Oil Change interval for XUV 700 was 20k initially, but was reduced to 10k more recently.

The best idea would be to just take the vehicle for a spin where you can reach allowable safe speeds (constantly) for at least less than 20 minutes when you feel you have clocked the usual regeneration mark.

Originally Posted by sbm

I would also like to connect through mail. Can you please allow email contact in your profile if you don't mind? Thanks

[sbm]

Originally Posted by arj2695

Hello there, sorry that it took a very long time to respond.

From my experience, the 150-160km interval between two subsequent regeneration is rather low. If your average velocity is always less than 25kph, then there is a high possibility for such a low interval.

Recently, I checked the average speed, and it was only 30 kmph during city usage.

Originally Posted by arj2695

One of the reasons for this is that sufficient temperature would not be available for completing a successful regeneration which could prolong a regeneration (which could cause oil dilution) and also limit the actual soot burnt off from the system. This causes the next interval to be reduced as well.

I too feel that the regenerations are just bringing the soot level below the alarm value rather than bringing it down to zero; that's why regen intervals are so low. Recently, I came back from a long highway trip spread over a week, and after that, I noticed that I hadn't gotten any REGEN warnings even after 200km of city driving. Let's see how it turns out. Also, I have started using zip mode in the city, which means less fuel and less soot, correct? By the way, is there any OBD device for XUV that can display DPF data on the phone?

Originally Posted by arj2695

About you being able to feel interruption in fuel supply is not usual. In general, the difference between when in regeneration and when not should be very minimal (slight variation in engine note and also mild perceptible heat near the Pedal area). So, I am rather confused when you say that you can fuel supply interruption.

When the regen is happening, at exactly 2000 rpm, there is a slight fluctuation in the engine output, just like you get what you get when your bike is about to get into reserve. Above and below that point, it's fine. Service tech says it's due to the post-firing of fuel for regeneration.

Originally Posted by arj2695

As you are consistently getting low intervals, it is best to keep an eye on the Oil level. As dilution increases, the lubrication effect of the oil will decrease drastically. It would be a wise idea to check and refill rather than just changing it for every 5000km. I vaguely remember that the Oil Change interval for XUV 700 was 20k initially, but was reduced to 10k more recently.

They have already mentioned in the manual that for city driving conditions, engine oil should be changed at 10k instead of 20k. I have driven around 6.5k km after my last oil change, and looking at the level on the dipstick, I can say that there is around 250–400 ml of extra diesel added to the 6L engine oil.*Now, adding extra engine oil will definitely increase the proportion of oil in this mixture, but the overall level will further increase. Mahindra service guys are completely ignorant of this. They are saying that it's normal, minor dilution is allowable, it's happening in all the diesels, Mahidnra knows about this, and they are working on it. Why are they working on it if it's normal? They have no answer to that.

Originally Posted by arj2695

The best idea would be to just take the vehicle for a spin where you can reach allowable safe speeds (constantly) for at least less than 20 minutes when you feel you have clocked the usual regeneration mark.

That is what I will be doing from now on. My concern is that it's not only me who is facing this issue. Many users are reporting similar behavior. Should I force the service guys and let them experiment with my car? I don't want to get my car messed up by them for something that's actually normal behavior due to my usage patterns. Is there any usual suspect that can cause such an issue in BS6 diesels? Like injector failure or fuel pump issues? Won't it throw up a warning and create other issues as well? The car is running absolutely fine, and the fuel efficiency is also good.

Also, I have read on the Innova thread that in city use, it performs active regen every 200km or so and also indicates the level of dpf choking along with indications when regen is going on. That also confirms my suspicions that it might just be normal behavior in my car. As both the cars have similar sized engines may be I can draw some parallel from there.

[Lalvaz]

Originally Posted by ninjanayak

The aim it is to improve air quality in our country and reduce tail pipe emissions. In diesel cars there is 70% reduction in NOx (Nitrogen Oxides) emissions and 90% reduction in PM (Particulate Matter) emissions compared to BS4. PM reduction was done by using a DPF which traps these PMs and NOx reduction is done with the help of either EGR+LNT(NSC) or EGR+SCR technology.

A DPF needs to periodically regenerated when its completely filled with soot particles coming from the Engine and this is generally done at high temperature inside the DPF. Diesel fuel is deliberately released in the exhaust of the vehicle which is burnt in the Oxidation catalyst (DOC) and the heat released from this combustion is used to burn the soot collected in the DPF.
This is the basic principle by which a DPF system works without getting too technical about it.

EGT design also has an important role into this especially in Indian conditions, which many OEMs are finding out now.
Passive Regen occurs when the DPF is operating at 250-400degC temperature, when the Nitrogen Oxides in the exhaust react with the Soot particles to generate CO2. This temperature is present when driving at more than 20kmph and at sightly higher average engine rpms as I said in previous question. So if you're driving at decent speeds the DPF will observe good passive regen.
.[/quote]


Can you please elaborate on this part in bold? How does Nitrogen oxide react with soot to generate CO2 ? I'm not sure I understand this.