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Any way to stop the engine from running so much in the winter?

51K views 93 replies 39 participants last post by  Fiumag 
Correct the MAF sensor also provides the engine fuel computer with air temp.

The question is: Is this temp sensor used only by the climate control system and the display for 'outside air' temp.
Does the Battery TMS use 'outside air temp' and does it share this same sensor? (Does anyone have access to the wiring diagram)

A set resistor replacing this sensor would keep the engine from coming on at low temps. (This would be used only seasonally. which came WAY too early this year ! )
The 'outside air temp' display would be wrong and you'd have to return it to stock before taking it to the dealer for any service.


I don't want my engine coming on. I'm fine with electric heat.

For example:
I experienced a situation today that is not good for the engine.
>Left the house, indicating 20° outside temp.
>Within 1/4 mile of my destination the engine came on, indicating 14° outside temp.
>I shut down the car because I had arrived at work.
>The engine did not even run 1 minute.

There is now moisture in my engine, engine oil and exhaust system,, just sitting there,,, until I finally run the engine again. ( which I will do on the way home to make sure the engine and oil get fully warmed up).

Dang it.... I was within 30 miles of 1000 miles without gas !!
I can live without the outside air temp display seasonally, in exchange for not having the gas burner come on !!

somms,
Thanks for all the research !
 
somms,

Thanks again for getting this ball rolling!
You have a workaround.
My only concern is the battery TMS and where it gets its temp sensing from.
This quote is from the following linked thread:
These passages permit the cells to be cooled or heated depending on operational requirements. The coolant inlet to the battery housing includes a debris filter, and a variable high voltage heating element that operates directly off the 360V Lithium Ion battery, and able to accurately heat the coolant when the battery cells are too cold. http://gm-volt.com/2010/12/09/the-chevrolet-volt-coolingheating-systems-explained/

How do you know your battery is happy?

The approach I may do is: parallel twin wires at the original temp sensor and run them into the cabin.
(This may be a be chore.) And have a pot to dial in a correction factor, always to a slightly higher temp, and only as it gets close the 15° 'Engine running' point. You can watch your adjustment on the display.
This would be much harder to conceal when taking the car in for service. I would rather use your approach but,,,
We have to find where the battery TMS gets its air temp sensing from.
 
Fredo,

I looked over your thread on TMS. You plot 'air temp' but we still don't know which temp sensor the TMS is using.
There are 2 that I know, the one provided by the MAF and the on up front that the temp display and 'ERDTT' uses.
Are there more? Which one were you plotting?

Your idea of blocking off the grill is not adequate to keep the ERDTT from running the engine when it's less than 15° F.
Why would it be warmer up there? The transaxle and inverter are making a little waste heat but any wind speed at all and that is gone.

I won't be using a pot to 'dial in' a temp slightly above 15° until I know for sure if this affects TMS.
 
So you're saying the TMS does not really monitor ambient air?
It is only looking at the 16 battery cell temp sensors?
How does it decide to just run the 'radiator' fans or turn on the AC compressor also in hot situations?
I'm pretty sure I just had the fans on during hot weather charging last summer.

I am concerned about the air temp sensor because I don't want my engine to come on for 30 seconds at the end of my commute and then shut down with condensation everywhere. That's what happened to me a few days ago.

I can commute just fine with electric heat only.
I want to decide when I need 'ERDTT'.

I am just trying to figure out if 'adjusting' the ambient air temp sensor is messing with the TMS system.

Thanks for all your help, I have Torque running on a 7" tablet but don't log anything, just watch my many many gauges,, Bill
 
Exactly! I want the option of NOT running the gas burner when I don't want it.

It was not "random condensation". It was a worse case scenario of the engine coming on for the first time in maybe a month and it's 14°F and the engine ran for < 1 minute.
Can you imagine what the inside of the combustion chambers and the entire exhaust system looked like?

I had the option of running the engine for 30 mins. on the commute home and getting it warmed up thoroughly. I pressed HOLD.

Now I want a workaround to make sure that does not happen again.
 
Man, this is getting complicated. Now it affects the 12V battery along with the HV battery???

So what about putting a resistor in parallel or series (it's early) with the original sensor to offset ambient temp up 10° or 20°?
This offset would be easy to figure if you want to know what the real outside air temp is from the display.
10° would work for me. Canucks would need more.
 
Of course parallel !!

Now, what would that value be for a 10° positive offset? Or a 20° offset?
But please,,, let it not be that cold this winter that I need a 20° offset to keep that smelly gas burner from starting up!!!! Please !!
 
The lawsuit sounds silly, especially when ERDDT is spelled out in the Owner's Manual.

However, GM could shutup us cry babies that hate ERDDT with an an Optional SW load to allow disabling it, or adjusting the set point lower than 15° F.

Will it ever happen? No way..... They're way too busy to make existing owners happy with a new optional SW load.
 
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