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Kia Optima SW PHEV 2018
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Discussion Starter · #1 ·
Hi all,
Does anyone of you have any tips on how to avoid the petrol engine to start when driving in EV mode? I thought it had to do with the inside temperature of the car, i.e. it starts because the passenger compartment is too cold, but there seems to be a lot of other reasons as well. Today I used a combined engine/passenger compartment heater before departure but the petrol engine started almost immediately anyway. FYI it is around 10 degrees celsius here.

I am very interested in knowing more about what triggers the petrol engine in EV mode. Please share your wisdom! :)

(Yes, the battery is fully charged).

BR
Johan
 

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I don't know much more than you do, but can confirm that if the HVAC system is active the engine is much more likely to start up. I suspect they also keep a "time since last engine run" counter and force the engine to run every X days just to keep it lubricated and ready to go (also to slowly cycle the gas in the tank), because most other PHEV's do that. But I don't have any details about actual timeings, etc...
 

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Discussion Starter · #3 ·
I don't know much more than you do, but can confirm that if the HVAC system is active the engine is much more likely to start up. I suspect they also keep a "time since last engine run" counter and force the engine to run every X days just to keep it lubricated and ready to go (also to slowly cycle the gas in the tank), because most other PHEV's do that. But I don't have any details about actual timeings, etc...
have you expereienced any difference whether the HVAC is cooling or heating?
 

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My engine runs only when:
1. The HV battery is discharged,
2. I accelerate hard, or
3. The heater is on, regardless of how cold it is outside.

I've had gas sit in my tank for a long time (many months) without the car deciding to use some up on its own. The car has no other way to warm up than to run the engine. But to cool down, the AC is pure electric, so it just increases the load on the battery, which has only an indirect effect on when the engine runs. I've made many trips using the AC without the engine running at all.

I tend not to use "auto" to control the temperature. Maybe the OP's thermostat is being aggressive about trying to bring the cabin up to temperature. Does the engine run if you turn the climate control off?
 

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Discussion Starter · #6 ·
Thanks for your reply! I'm surprised to hear that you've been able to go several months without triggering the combustion engine. But great, I guess :)

Putting the HVAC in "off" mode absolutely reduces the probability of the combustion engine to start but doesn't eliminate it. A few weeks ago I had to frequently move the car a very short distance every day and it ran in EV mode the firtst 10 (or so) times but the 11th time the engine started, only ran for a couple of seconds though. I figure it has something to do with petrol fumes in the fuel system that have to be burned (similiar to what @summetj mentioned above).

On another note, I figure it can't be healthy for the petrol engine to only run for a very short time now and then. My experience with ICE:s is that they should be driven for some time (more than an hour) or not at all. There has been news coverage last winter of KIA owners experiencing problems with coking when only driving in EV mode, even though the retailers claim that it shouldn't be a problem. I don't know. Is this something you've heard about?
 
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