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-   -   Seltos ISG starts engine on its own (https://www.team-bhp.com/forum/technical-stuff/280983-seltos-isg-starts-engine-its-own.html)

Hi, I recently got delivery of my 2024 Seltos X-line Diesel AT.

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.

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?

Is your AC on during this? If it is getting hot, the engine may switch on to power the AC.

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.

Guys start-stop systems do this to keep the aircon running. Happens in my slavia too.

Try this: set the aircon temperature to 24 degrees or a a relatively high temperature or even turn off the a/c completely and roll to a halt. Let the ISG do its thing. Then reduce the temperature to Lo or turn on the aircon. I'll bet that the engine will crank immediately.

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?

Edit: Also the title is a bit misleading as I initially thought the vehicle turned on by itself without you starting it.

Turn off the AC or keep it in heater mode and see the reaction - it wont repeat itself.

It is the AUTO mode of the Aircon trying to keep the temp at set point.

It definitely is due to the AC working to maintain the cabin temperature. I love how Kia is thoughtful in implementing the Start-Stop system and has various parameters set to help the system to determine whether it should or shouldn't engage. In my case, if I have just started the car and if I stop due to a signal ahead after driving for few mins, the system wouldn't stop the car till the set temperature on the AC is reached.

Comparing this to my XUV700, that is one stupid implementation of the sysyem. Even if you have just started the car, press the brake and the engine will turn off, take your foot off the brake or turn the steering wheel, the engine will turn on, no matter what temperature is set. In Seltos, if Auto Hold is engaged, you can take your foot off the brake and the engine will continue to be off as long as other parameters of the system are met. Do that in the XUV and it will turn on!

This is normal. When the engine is off, all the accessories are being powered by your 12V car battery. When the car battery % drops a certain amount or when the climate control detects that the temperature of the cabin is getting high, it will turn the car back on to recharge battery + turn on the AC compressor.

Remember, the AC compressor is still powered by the engine. Only the fans will work when the engine is off. Electric AC compressors that can work from the battery can be only used in strong hybrids or EVs since they have very high voltage secondary batteries to power the electric motors.

This isn't an issue but the car being smart to save the battery and also to keep the cabin cool.

Happens in my seltos too. Make sure when you stop, press the brakes a bit more and the car would turn off. If you keep the AC off car won't turn on Unless you shift or drive.

Excellent implementation of ISG imo.

Engine can be triggered on anytime by the start stop system. There are numerous reasons that can be the cause and can be understood by carefully going through the diagnostics measurable signals. The engine controller will get release or clearance signals from various other systems for enabling engine stop under start stop mode. One of this will be no longer true and that will trigger engine restart.

Apart from the regular engine start triggered by the release of brake, the following can also cause engine ON trigger:

• Demand from the AC system for engaging compressor
• Depletion of brake vacuum in the booster
• Excessive power consumption or battery voltage dropping below a threshold

There can be other reasons as well such as driver removing seatbelt or opening door etc depending on how intelligent the system is. So you should not bother about why the engine turns on since that's not a misbehavior.

Even if only blower on in the car, the engine starts if I move the blower above speed 3.

As others have said, it's due to the air conditioning system . In our Skoda Slavia, sometimes with the auto start stop enabled, the engine wouldn't shut off during the peak summer. And with the temperatures going down, the frequency has decreased to 3-4 times at max. In our Skoda, it works irrespective of whether the AC is in auto mode or not. Only minor downside, according to me , is that it may give additional stress to the battery, causing more frequent changing of the battery.

XUV700 also has somewhat similar behavior, like others have mentioned there are several factors that decide whether to keep the engine ON OR OFF. Like AC, battery voltage, steering movement etc. One thing I have noticed in XUV700 is if you move the gear to N in P at variant, it by default turns on the engine. Everything same if I move to D the engine turns off. Not sure whats the logic behind keeping the engine ON while on neutral. Is the behavior similar in other cars or this is a Mahindra specific implementation?

Doesn't the instrument cluster display the reason for the start? In my Altroz, when the start-stop system is on and the engine turns on automatically, it displays the reason why the system was overridden (Battery Voltage too Low, Cabin temperature too high).