I have a new Kia Stonic 2020 1.0L T-GDi ISG , got it on July and 8500km on it

It already had an issue with miscalibrated hill assist sensor (already fixed) so I wonder if it has other issues ... what I’ve noticed:

  1. With the car off , if I shift the gear into reverse (using the clutch properly of course) it makes a clanking noise. Same for 1st and 2nd but not 4th and 5th. Is this normal?? I never tried it right after I got it so not sure
  2. The car vibrates a lot when accelerating even on slight uphill at around 1200-1600 rpm. It seems to have some sort of resonance at around 1450, goes away entirely by 1600. It’s a low vibration that shakes the interior slightly. It isn’t huge but it is disconcerting , it doesn’t sound “good” like it does at 2k+ rpm. However it doesn’t happen on 1st gear so may be just need to keep in higher gear , but needing to stay above 1600 rpm I feel a bit limited.
  3. The idling rpm fluctuates from 1200 to 800 right after starting it , I hear this is normal though
  4. The low vibrations happen while idling too. If I slowly rev to 2k then let acceleration go, as it’s dropping back down it passes through some rpm where it does the low vibration , and canbe rattly once it gets to 800
  5. I made this video of reviving while idling , as the rpms go down they go down smooth and then sort of glitch at 1450: https://youtu.be/L5msLstt1Kw

thanks in advance for help and sorry if this is all normal! It’s my first new car so just wanna be sure I maintain it properly.

  • 1
    It is under warranty so take it back and get your queries checked. Even if we were sure what the fault was you cannot touch it.
    – Solar Mike
    Commented Jan 5, 2021 at 13:38
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    Welcome to Motor Vehicle Maintenance & Repair! I agree with @SolarMike here ... if you believe there could be an issue, you need to take it to the dealer's service center and have them look it over. Anything "rattly" does not sound normal to me. Commented Jan 5, 2021 at 17:23

1 Answer 1


I'd like to respond to #2 and #4. The problem is likely poor combustion due to carbon deposits on the intake valves, spark plugs, fuel injectors and inside the combustion chambers. It is a very common problem with the GDI fuel system on your vehicle at that km's. I had exactly the same problem with two new cars with approximately the same km's (Jeep Compass and Mercedes E350).

The phenomenon is known as "lugging." The engine shakes at low rpm, at low speed. As you have discovered, it can be compensated with higher rpm or a lower gear. In your case, the root problem is uneven combustion and thus a lack of power.

The problem can be tough to remedy. Start by replacing the air cleaner. Add an entire bottle of this cleaner and this additive to a full tank of high-octane (RON 91) fuel. Note the heavy, 4x initial dose of Star Tron additive. Drive the car in a spirited manner, with plenty of heavy acceleration and at least five full-throttle blasts on the highway close to redline rpm. Avoid short trips under 15 minutes on a cold engine. Drop to a lower gear and maintain a steady, 3,500-4,000 rpm on the highway for at least 15 minutes (30 min. is optimal). After running half the tank with additives, spray this cleaner through the intake shutter. Continue to drive with additives until tank is near empty. When finished, change the crankcase motor oil (even if it is before its scheduled maintenance).

In the future, take preventive steps to maintain a clean engine. Continue to add a few drops of the Star Tron at every refill, using name-brand petrol. Avoid short trips under 15 minutes before the engine is fully warmed up, especially when outdoor temperatures are below 7° C. Drive the engine up to at least 3,500 RPM a couple of times during every warm-up cycle, and cruise very steadily at normal highway speed for at least ten minutes a day. Using petrol with an octane rating below 91 will accelerate carbon buildup in your particular engine (see your Owner's Manual for further details).

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    Awesome reply thanks :) just the sort of info I was looking for
    – Claudiu
    Commented Jan 7, 2021 at 19:54
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    Let us know how it works out!
    – Carguy
    Commented Jan 9, 2021 at 1:39
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    Basically they said everything is normal.. it's under warranty, no cost for the inspection, but they did full diagnostic and saw nothing out of the norm
    – Claudiu
    Commented Jan 27, 2021 at 22:05

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