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The engine won't come on unless the water temp is also below a certain temp as well, so it's 2 things....
MrEnergyCzar
MrEnergyCzar
I dont believe the coolant temperature has anything to do with the first engine start of a cycle, its for the subsequent ones that it is used to gauge when to run a second, third etc. You can pre-condition in a garage and warm everything up but as soon as the temp hits the magic number it switches on, sometimes less than a min after leaving the garage after pre-conditioning.The engine won't come on unless the water temp is also below a certain temp as well, so it's 2 things....
MrEnergyCzar
AFAIK the 114F came from my testing with a ScanGuage. See this thread. As well in that thread I pointed out that when I do precond/remote_start that my ICE WT (water/coolant temp) rises. saghost can't recreate tho. I've never tried it more than twice to see how I could get it (would need to recycle/start/stop) to get around the 2 times precond limit tho.So, yes, engine coolant temp does matter. But if the car has been sitting off for awhile, the coolant temp won't be above 104F*, so the engine will kick on every time if the ambient temp is <26F.
*I've seen several people on this forum who use a DashDAQ to monitor actual engine coolant temperatures, and some have reported that the temperature threshold for the engine coming on is actually higher than 104F -- more like 114F or so.
Not true about battery temp. The engine coolant loop is not physically connected with the battery coolant loop in any way. There is no exchange of heat between the two. The battery coolant loop has it's own electric heating element that manages the battery temp. See any one of the 1000's of posts about this.gschuck: The engine is running to maintain the proper coolant temperature. The coolant is used to both warm the cabin, and maintain the battery temperature.
Well, if you do get ambitious and make a workable hack, I suspect many Volt owners would be very interested. As you likely know, GM is in no rush to address either a ERDTLT "off" switch, nor a faux Hold mode using a different hack of the OAT sensor.I'm not ambitious enough at this point to attempt it myself, but what's to stop someone from wiring a resistor with a relay switch in parallel with the outside air temperature sensor to reduce the effective resistance of the OAT and fool the car into thinking that it's warmer than it actually is? Idk where you'd route the wires to get them into the cabin, but if you did you could have a simple on/off switch and a few AA batteries to engage/disengage the relay.
Can anyone think of any risks to this approach? I'm not sure what else the OAT sensor might be used for, but I'm thinking that if the change in perceived temperature was relatively small, any unintended side-effects to the car's operation would be minimal.
(In that other thread that I linked to, the discussion was basically the opposite: it was about fooling the Volt into thinking that the outdoor air was colder in order to force ERDTT as a way to get a Hold mode in 2011-2012 MY's. Tboult mentioned using a peltier device to actually cool the OAT sensor. That could be an alternative approach compared to splicing in resistors and relays.)