[navrddy]

Engine RPM fluctuation in Diesel vehicle, is a topic related to partial blockage of Nozzle holes, mostly due to carbon deposits like soot.
Root cause are many, mostly related to adulterated fuel.
Best solution is get those fuel injectors out, clear them using diesel test rig with actuation ECU/waveform generator., to confirm spray pattern and put it back.

[vaibhavyagnik]

Originally Posted by ashis89

It could be an unhandled exception too.

Nothing is impossible. But generally manufacturers tend to err towards caution. So if there was an exception, your dash would light up like a christmas tree rather than no lights. If your car is in warranty you may go hunting but do remember that there is also a chance of introducing problems in finding the solution due to our ill trained and calous attitude of our technician.

I again advise you to trust your car. It will tell you if there is an engine problem. Also start with the easy and non-intrusive things first. Just add the liqui moly diesel purge and see.

[bharani.cl]

I have been having the same issue in my 1.5 D Seltos. This has been going on for months. The car is almost unusable during monsoon. Later I found out that one of the cylinder is missing ignition causing erratic engine RPM. There is almost no torque when this happens, the vehicle cannot move faster than 30-40 KMPH. The vehicle has been a disaster. The service folks are clueless and have not idea why this is happening.

[Sudeep_Kimster]

My car a MY2020 Kia Seltos GTX+ D AT started this issue, once I was in Chennai,
After using my car in Pune for almost 1.5 years, around SEP 2023.
Me and @ashis89 had a long discussion about this.
This happened in Idle for me, and when driving I feel loss of power and unusually louder engine note.
The moment you reboot or shut and restart the car, it runs fine.
I gave it Capital Kia, Chennai and they couldn't find anything unusual.

Generally the firing order of a typical inline 4cyl engine is 1-3-4-2, and the engine is naturally balanced, incase there is misfire or lack of combustion in any cylinder it might create unusual vibrations, which I am suspecting it happens. Must be some kind of timing related issue with injectors spraying.

Now the issue has not comeback post servicing, but every time I in idle, I try consciously to observe if it comes back.
And the vibrations are pretty sinusoidal.it repeats and where it happens the car shakes.
Need to address it to Kia for a thorough check of their ECU Mappings,
And need to understand if any Hyundai Creta/Hyundai Verna/Kia Sonet/Hyundai Venue owners have also observed the same.

I doubt its DPF related.

[bharani.cl]

Originally Posted by Sudeep_Kimster

My car a MY2020 Kia Seltos GTX+ D AT started this issue, once I was in Chennai,
After using my car in Pune for almost 1.5 years, around SEP 2023.
Me and @ashis89 had a long discussion about this.
This happened in Idle for me, and when driving I feel loss of power and unusually louder engine note.
The moment you reboot or shut and restart the car, it runs fine.
I gave it Capital Kia, Chennai and they couldn't find anything unusual.

Generally the firing order of a typical inline 4cyl engine is 1-3-4-2, and the engine is naturally balanced, incase there is misfire or lack of combustion in any cylinder it might create unusual vibrations, which I am suspecting it happens. Must be some kind of timing related issue with injectors spraying.

Now the issue has not comeback post servicing, but every time I in idle, I try consciously to observe if it comes back.
And the vibrations are pretty sinusoidal.it repeats and where it happens the car shakes.
Need to address it to Kia for a thorough check of their ECU Mappings,
And need to understand if any Hyundai Creta/Hyundai Verna/Kia Sonet/Hyundai Venue owners have also observed the same.

I doubt its DPF related.

Hey, were you able to find the root cause of this. Has it been fixed.

[iamsai_iyer]

I too have seen this in my SELTOS 2022 HTX diesel .
My seltos has run about 6000 kms. I noticed this a few weeks back. It felt like a truck idling. I immediately took it to the service station. I relayed this incident. They took it in and by afternoon I get a call saying they found nothing wrong, however they did notice an error in the ECU, which as per them, they removed.

I noticed the uneven idle on my drive back home on the same day, but it disappeared after a few minutes drive.

I have’nt noticed it since.

[ashis89]

Sharing an update here regarding the issue I had reported. Apart from the irregular idle observed at times, I had also noticed a stronger exhaust gas smell when the car was idling. What worried me was that the car had run only 300 kms (in city) post the last service and nothing was found during the service. I got an OBD reader too but that didn't give any error codes (but showed the rpm fluctuations).

I had a long trip in December - January, covering 5500+ kms. After starting from Bangalore and covering about 200 kms, I didn't see this issue again. Car pulls better than earlier. Exhaust gas smell also reduced considerably.

Since then, I have looked out for the idle once in a while but didn't find anything wrong with the performance and idling RPM. Exhaust smell increases once in a while.

PUC was renewed in Jan and the numbers are slightly below what I had last year and much below the threshold.

If I were to deduce, I would bet on a near full DPF which could be giving the rough idle. That would also explain the smelly exhaust fumes. And as per design, no errors codes pop up until the DPF is fully clogged.

Originally Posted by iamsai_iyer

I too have seen this in my SELTOS 2022 HTX diesel .
My seltos has run about 6000 kms. I noticed this a few weeks back. It felt like a truck idling. I immediately took it to the service station. I relayed this incident. They took it in and by afternoon I get a call saying they found nothing wrong, however they did notice an error in the ECU, which as per them, they removed.

I noticed the uneven idle on my drive back home on the same day, but it disappeared after a few minutes drive.

I have’nt noticed it since.

What was the error code in the ECU?
See if you can track the occurrence of the issue and the car usage (pure city vs. highway).

[iamsai_iyer]

I’m afraid, they didn’t share the details of the error. However, in my case, things, were a little different. The rough idle occurred nearly 3 weeks after my trip to Kanyakumari. Then it happened again, briefly, for a few seconds yesterday. I had completed a round trip to Hubli the day before. I would again be travelling to Mangalore on Monday.

So in my case I’m guessing it may not be related to DPF. Also I did get a DPF regen required error before leaving for KANYAKUMARI in the last week of December & I was able to do regen process by myself.

[Sudeep_Kimster]

Originally Posted by bharani.cl

Hey, were you able to find the root cause of this. Has it been fixed.

As @Ashish89 said, its been rectified post return from servicing
Didnt return till now.