2.0T Engine stutter when accelerating (UK)

[irtg]

Only had my stinger 6 weeks and am getting stuttering on acceleration. Engine is warm, it's not Traction control, ISG is off - almost feels like it's running out of fuel. No engine warnings or lights though.

Seen a few threads from way back in 2018 talking about fuel pump and transmission recalls, but it doesn't seem like there were any recalls in the UK (when I check online it says there are no recalls for my vehicle - 2018 GT Line, engine made in Korea).

Looks like a trip back to dealership as I've still got 1.5 yrs warranty on it. Totally gutted, have only driven her about 700 miles

Was wondering if anyone in Europe with the 2.0T has had similar issues and resolved it?

 

[7Andrei7]

Under hard acceleration? At all rpm or only in some range?

 

[irtg]

I would say about 70% throttle, accelerating from low to mid rpm range (in auto mode, I rarely use the manual shifters). First occurrence was in sport mode, switched to Comfort and it happened again. I drove pretty cautiously after that as I was on motorway and was worried about it stopping completely so was very light on the throttle and didn't get any more coughs from the engine.

Tank was about half full, filled up with 97 RON yesterday just to see if that made any difference and the issue seems to have gone. I'm suspecting it may come back though. The car had been undriven for a week prior to the stuttering, not sure if that has any relevance.

 

[7Andrei7]

It could be more things. My first thought, since you just bought the car, is to make sure the previous owner replaced the spark plugs and the air filters.
But best is to make that trip to the dealer.

Maybe also use a GDI cleaning additive. Maybe there are some deposits on the fuel injectors from bad fuel? The manual advises to use one can after every 10k km service. This would be the easiest to try and a can of additive is 7-8€.

I had 2 instances where I felt some intermitent hesitation but nothing bad, you could just press the acceleration harder and it would go away.
Once was before I had a recall for the GFP regeneration issue. Yours should not have this if it's 2018. GPF were introduced in '19.
Second was when I used some lower quality fuel. I say this because it went away when I used some other fuel.

 

[irtg]

Thanks for the info. It should have had plugs / filters checked prior to purchase as it was from a KIA dealership with full pre-sale checklist.

I had been using cheaper supermarket fuel, and since I topped up with BP 97 RON I haven't had the issue again. I'll have a look at the cleaning additive too.

One thing I hadn't realized is the UK/EU octane numbers are different from US. I had assumed that because we have 95 RON as standard, we don't need to worry about octane. But it turns out 95 (RON) is the same Octane as 91 (PON) at the US pumps. So I'll be using 97 upwards from now on - the car feels much more alive now, but maybe that's placebo effect.

I wouldn't say it was intermittent hesitations though. It was quite a strong cough (almost stall) so I was concerned the car would stop completely.

Booked into dealership for a look, so lets see what they say. Tempted to buy better plugs and reduce the gapping (as recommended in the tuning sections) just as added precaution.

 

[7Andrei7]

I change my plugs every 50k km instead of the 70k recommended. Just to be on the safe side.
For fuel, I mostly use 95RON but I'm aware that's the minimum required. So in case there is some lower quality 95 then there can be some problems.

As for the dealer... I can tell you from my experience that they have no clue about maintenance. At least my dealer. I always needed to remind them about brake fluid changes or other not so regular stuff.

But I'm out of warranty now (180k km) so I've stopped going to them for minor stuff

 

[irtg]

Wow good to see the 2.0T can manage the higher mileages Mine has done less than 30K km even though it's 5 years old.

 

[irtg]

Update - the issue definitely seems to happen when accellerating from low revs (if I manually drop gears to over 3K RPM I can floor it and there's no stutter). But if I'm driving around at lower speeds and want to accellerate (70% + throttle) there's a significant stutter, almost like a misfire.

The issue also went away when I filled up with higher octane fuel as mentioned earlier, but now I'm down to 50% fuel it's happening again.

Car is at dealers for investigation tomorrow so fingers crossed they find something. At least I can easily replicate the issue now.

 

[7Andrei7]

Hope they find the problem!

 

[irtg]

As I half expected, dealer mechanics couldn't replicate the issue, and found nothing in the diagnostics history. They did some sort of reset as my vehicle settings had changed (active sound etc) - maybe they just disconnected the battery or something.

Anyway, couldn't replicate the issue driving home myself so hopefully whatever it was is gone. I'm going to keep using 97 / 99 RON Shell / BP fuel from now on and stay away from the supermarket stuff. Fingers crossed the hesitation won't come back.

 

[7Andrei7]

As I half expected, dealer mechanics couldn't replicate the issue, and found nothing in the diagnostics history.

I went through this with a parking sensor. It was working on and off for one year. Every time I was at the dealer it was absolutely FLAWLESS
Sadly, the Stinger does not keep any logs for minor errors. So even if there is an anomaly, unless it triggers a check-engine light, it will go away.

 

[irtg]

Unfortunately it's still not fixed and is driving me mad. When it starts I'm getting 4 or 5 misfires in quick succession, sometimes so severe it feels like I've hit the brakes.

Been back to dealer for a more thorough 'investigation'. Again they said no CEL and can't replicate the issue. They reset every sensor on the car and handed it back. Not fixed so it's booked in again. They seem reluctant to do any work to investigate without any codes showing up.

I can replicate it on demand now, have told them I want them in the car with me and I'll demonstrate it happening. Have narrowed it down to the following:

1. Only happens when accelerating from low revs (under 2,500 rpm) which is where it sits most of the time in comfort mode
2. If I accelerate hard enough for the auto box to drop a couple gears, it doesn't happen
3. Problem is exacerbated when the car is heavy (passengers) or going up an incline.
4. Doesn't seem to happen until the engine has warmed up - I get about 10 mins of trouble-free driving when it's cold
5. Seems to be getting worse over time. It's now happening when cruising at 40-50mph if the revs are low enough
6. When first starting the car cold, idle is sometimes quite rough and revs go up and down constantly until it settles

Ruining the whole experience for me as it's been happening within weeks of buying the car. I'm having to use manual gears in sport mode all the time to keep revs above 3K, and always worried it's going to fail me when I need to pull out into traffic etc