Peculiar behaviour of the auto start-stop system in some cars

The vehicle just starts randomly after a few seconds. Sometimes its 12-15 seconds, sometimes 20. In rare cases 30 seconds

BHPian dushyantbangal recently shared this with other enthusiasts.

I am facing an issue with the ISG (Idle Stop and Go) system but I want to check with existing owners to see if that's how it works or if it's just my vehicle.

AFAIK, when you stop, the engine should turn off and once you let go of the brake, it should start. In case auto-hold is enabled, it should start only when you press the accelerator.

The above is apart from certain conditions that KIA has mentioned in the manual (eg. You open the bonnet or driver seatbelt etc).

However, in my case, the vehicle just starts randomly after a few seconds. Sometimes its 12-15 seconds, sometimes 20. In rare cases 30 seconds. This happens even if I have kept it on auto-hold (to remove any doubt of my slightly depressing brake).

Sometimes it doesn't even turn off the engine!

I told this to Epitome KIA Whitefield, Bangalore during my first servicing. They didn't do anything and said it was working. Then I escalated it further, and they started saying "Very minor voltage fluctuation can also cause this or even when you let go of the brake a little bit".

When I escalated it further with one of their managers, they tested it and acknowledged that there was an issue.

They kept the car for a few more days, fully charged the battery, tried with a new battery, recalibrated sensors, put in sensors of thei4 test vehicle, etc. But in the end, they said "We have checked everything, there is no issue". I appreciate their efforts, but just because you didn't find the cause doesn't mean the issue doesn't exist!

I need to understand from other Seltos owners if this is how it works for them as well, or if it's just me.

If it's just me, I'd like some advice on how I should fight/pursue this.

Here's what BHPian Jaggu had to say on the matter:

My guess was also same, if the battery is low the system should start and charge it to avoid being stranded. So this might have kicked in.

How is your running? Daily how many kms and how much of it are you stuck in traffic?

Here's what BHPian GTX+ had to say on the matter:

Hello... I own the FL GTX+ DCT and my car behaves exactly as you have described. Some times even with auto-hold and ISG active, it does not turn off.

My take on this, and I have been observing this for a while, is that when I brake gently, slow down to almost a slow crawl and come to a stop, I guess the sensors feel that I may immediately move again and hence it does not turn off the engine. However, whenever I have braked hard (or normally), as far as I remember ISG has always worked. Now, this is purely based on my experience and observation, do not claim it to be THE reason.

But given that there are so many conditions listed by KIA for ISG to operate (or not operate), one may never know which one is being met and which isn't during a particular instance.

Here's what BHPian praveen_v had to say on the matter:

I have seen similar behavior as well. There is no fixed time to how long it will stay off due to so many factors that are getting checked. And yes, sometimes it might not turn off at all if any of the parameters are not met.

One more thing I see is if I keep auto hold disabled, then come to a stop using brakes ISG will turn off the engine, then I enable auto hold to free my feet and then release the brake pedal, it immediately tuns on the engine even though auto hold is now enabled. Does this mean I need to keep the auto hold ON all the time for the ISG to keep the engine turned off?

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