Facing DPF & low mileage issues on my Alcazar; Few queries to ask!

The car has been regularly service at a single A.S.S, is 26 months old, covered 120k km plus and under warranty.

BHPian sids1811 recently shared this with other enthusiasts:

A Technical query

Issue Faced : Loss of mileage and repeated DPF warning

The car has been regularly service at a single A.S.S, is 26 months old, covered 120k km plus and under warranty.

After the last service the DPF light came within 600 km after the service, generally DPF warning was faced once between any 2 services as we have a very highway heavy running. The A.S.S was duly informed and they again took in the vehicle for a detailed examination.

Their analysis on date after examining the complete vehicle on multiple parameters over a week and trying out with replacing several parts for short term was that the engine needs to be checked as everything else including DPF system is working fine but the frequency of DPF warning has increased.
They checked the engine for compression in our presence and as told that the required pressure should come at 25.

Upon inspection, the pressure came between 18-21 in all 4 cylinders and they are now saying that the engine needs to be opened and rectified under warranty and parts such as piston / rings / gasket will all be changed under warranty and the car needs to be with them for atleast 3 weeks for the work to be done.

Queries:

1. Can this engine issue cause lower mileage and repeated DPF ?

2. Is it normal for such issues to be there after just 120 k km (Our Creta is at 280 k so this seems too less)

3. Is it ok for the Engine to be opened ? Can there be future issues related to it ?

4. Even if the Engine is corrected, will it be wise to continue keeping the car for long term ?

5. Any other course of action advisable ? As the car is still under warranty, the A.S.S has told our costing will be bare minimum and well under 10 K for the whole process.

Here's what BHPian Bsilver replied:

Answering your questions one by one:

1. Yes, any damage to the internals of the engine will take a toll on the combustion process going bad. And if the combustion process is not done correctly it does hamper the fuel efficiency of the vehicle. But before opening up the engine, all other check points need to be cleared. There can be bad MAF/MAP sensors, bad camshaft position sensors, bad injectors, bad fuel pump, bad ignition timing. There are so many things which can go bad, and all need to be visited with utmost attention. Just by chnaging any part one cannot get to the root of the problem. I would suggest to visit a very competent FNG for a second opinion.

Firstly check fuel system, right from the LPFP, check if pressure readings are normal (you need to refer workshop manuals, or check part specifications). You need to log these readings as they may behave differently at different scenarios. Then check the HPFP readings, then come to the injectors. Check deviation. Once this is done, you eliminate fuel system as faulty.

Secondly check for the aspiration of the engine. Check for piping leaks/boost leaks, check intercooler leaks. Check if your engine is breathing properly.
Accompanying this you can check for throttle body, boost control solenoid, PCV valve as well. Now if all fine, you eliminated 2 important things as faulty that is fuel and air.

Thirdly, check engine timing, since you told that the car has done 120k Kms, did you perform the necessary maintenance for timing kit change? If yes, see if the timing is correct. If no, then perform necessary maintenance.

Fourth, check the exhaust system, usually with your kind of running mostly on highways, the DPF should not get blocked. Check from manifold, turbine housing, EGR, and then DPF. If you feel DPF is blocked, there is a method to do a forced regeneration of it (present in many VAG software like VCDS to do forced regen), check with Hyundai if they can do a forced regen of the DPF. If not manually remove and clean the DPF and reset values. But if they can ( you have noy yet removed DPF, if you can force regen), then manually remove and clean.

If all of the above steps are done and no fault found, then you can examine engine( all steps includes cross verification of real time readings with OEM readings), instead of merely changing parts this is a more easier and efficient way to check for faults.

2. There is nothing like normal thing for an engine, this is all subject to maintenance. If you maintain everything, then engines can last a very long time. I have a friend who owns a Laura, tuned for last 10 years and crossed 2L kms on tune. If your maintenance is good, then this is not common.

3. It is absolutely okay for the engine to be opened. But the more important is, it should be fit back together with extreme care and precision. You can always open an engine, regarding the reliability, this depends on fitting it back. Call me crazy, but I opened my Fabia's engine around 20,000 kms earlier, just to clean out and was curious. I fit it back with the ultimate care (took 2 days), and till now no issues whatsoever.

4. As I told, fitting it back to OEM specs is hard. This all depends on workmanship. You cannot say about issues later, but if you are already fixed in mind about it, or have a little doubt. Repair the car, sell it.

5. Do the above as I suggested. If not, then there are other ways to do it as well, instead of opening the engine. But if none work, you will have to open and check it.

Hope all of this helps.

Happy Motoring!

Here's what BHPian narayans80 replied:

I've always had a faint clatter since early days and hasn't been as it was brought home. But I don't see the other symptoms though.

Just to confirm, you are comparing tank-to-tank vs tank-to-tank. In which case it looks abnormal.

Am asking because there is a 3 kpl error between MID and tank-to-tank.

If it helps, here's how my FE chart looks like over its lifetime. I get anywhere between high 16s to 18s. I used to get 17-18 before, but my commute times have increased by 5-10 mins since the start.

Entries outside this range are edge cases due to fuel efficient driving and/or colder weather that did not need AC.

I guess its the 1.6 BS4 diesel. BS6 diesel engines work with a lot different tolerances. I think the 1.5 diesel debuted late 2019 in the Seltos. I've not seen any other 100K in this engine in the forum, so yours is the highest mileage by quite a margin.

The only suggestion I could give is to talk with nagateja, who has gone through something similar.
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A curious question: Have you not noticed any difference in the drive around these happenings?

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