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Discussion Starter #1 (Edited)
The "Engine Running due to low temperature" has been discussed a fair amount. Some users have mentioned that when using COMFORT climate setting that it reduces the number of times that "Engine Running due to low temperature" happens and the ICE turns on. Others recently stated it did not have any affect. I normally use ECO so I tried COMFORT this morning.

In the past while in ECO and using the scangauge I've seen the ICE turn_back_on/ERDTLT on when the "WT" Water (engine) Temp drops down to 114F (45C). I've seen it vary in the ICE shut off when the WT goes up to 154F (67C) - 164F (73C).

Thought I would provide some empirical numbers with a statistical sampling of 2 <grin> using COMFORT/74/auto. [edit]The test was for 12 miles. Mainly 40 MPH driving hitting mostly of green lights. Also my test on the way home showed the same thing.[/edit]

Using a ScanGuage this a.m. while it was 13F (-10C) ambient temp out:
  • ICE came on after a couple minutes of leaving 55F garage and ran for 3 minutes (0.07gal) until "WT" water (engine) temp hit about 164F.
  • I noticed in my other vehicles that the Scangauge IA (intake air temp) would be very close to the ambient/outside air temp on my displays (Ford Exped, Honda Civic) BUT in the Volt I saw the the IA remain in the mid 40Fs ... remember the ambient outside temp was 13F (-10C). Perhaps I'm misreading this or is the Volt shutting some intake flap to help keep the ICE temp from dropping too fast.
  • "WT" dropped on my 12 mile trip to work to 123F (50C) and stayed there! Actually within a few miles of work I saw it go back up to 125F (51C) and 127F (52C) ... and the ICE was still OFF. In other words, I never saw it drop to 114F (45C) again where the ICE would turn back on. ... remember the ambient outside temp was 13F (-10C).
So does this mean that the 'exchange' stays open in COMFORT mode and the electric heat (COMFORT) is keeping the "WT" / ICE "warm". That is above the 114F (45C) lower threshold?!? I've seen that suggested by others.

P.S. Testing is a little annoying because I think my ScanGuage shuts off based on 0 RPM after 30sec so I keep having to press the 'home' button letting monitor the WT water (engine) temp down to the 114F (45C). I'm surprised noone with a DASHDAQ or other have graphed this ERDTLT processing ... but perhaps all those supertechs are in the warm regions. [update]:this thread setting SETUP->FUEL->TYPE->HYBRID to avoid his.[/update]

[update] Going home test and fan speed setting impact:
I was able to get similar examples on the way home from work as the way to work (above example). Plus experimented with fan speed impact to lowering the engine temp (WT water temp). Lower fan speed slows down the cooling of engine temp ... as makes common sense.

A little experimenting 2/3s the way home showed if I used AUTO (4 level fan speed resulting) then the "WT" water (engine) temp went to around 125F but if I used 2 level fan speed manually then WT temp would go to 134F. I even saw it climb from 125F to 134F when I switched to 2 level fan speed from AUTO/4 when I did the switch with 2 miles left coming home.

KEY POINT: both fan speeds still let the engine temp stay above the ~114F threshold that would have done turned ICE on (ERDTLT).
[/update]

[update] Using precond/remote_start to warm ICE for shorter ERDTLT initial runs:
Also see my post#12 of this same thread that shows how the ICE temp gets warmed up by doing precond/remote_start ... this should reduce the time/gas for the first ERDTLT running. [/update]
 

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Thanks for testnig this some more. I can say for sure that when I run comfort mode the engine comes on less, or not at all after the first time. This is from temps 10F-25F so far.
 

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The past two days have been cold so I've gotten the "Engine Running due to low temperature" message repeatedly. I typically run with FANS ONLY/AUTO RECIRC and am comfortable enough.

Has anyone else noticed that the ICE seems to ready gobble gas when turning on and off in this mode??? I've used more gas in the past 2 days than I have in the past 4 months.
 

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Discussion Starter #4
The past two days have been cold so I've gotten the "Engine Running due to low temperature" message repeatedly. I typically run with FANS ONLY/AUTO RECIRC and am comfortable enough.

Has anyone else noticed that the ICE seems to ready gobble gas when turning on and off in this mode??? I've used more gas in the past 2 days than I have in the past 4 months.
I think others have mentioned this as well. The reason seems to because it runs at a higher RPM to heat up the ICE/WT quickly so it can shut off. This is likely using less gas than running at a lower RPM for a longer period of time to heat up the ICE/WT. Try COMFORT. I thik your FAN ONLY setting is just pulling the heat out of the ICE/WT faster since the electric heaters are not running. I've never used FAN ONLY in these winter temps but I have used ECO and that is very different than my COMFORT testing this morning.
 

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I want to ask how *far* your commute is, because that could be affecting whether the coolant has enough time to cool down. My commute of 30 miles each way will typically result, on very cold days, of the engine coming on 3 times no matter what I do. I usually try to keep the heater off until i see the engine come on, and then I switch to comfort, figuring I'm not going to burn that much battery power while I'm using heat from the coolant.
 

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Discussion Starter #6
I want to ask how *far* your commute is, because that could be affecting whether the coolant has enough time to cool down. My commute of 30 miles each way will typically result, on very cold days, of the engine coming on 3 times no matter what I do. I usually try to keep the heater off until i see the engine come on, and then I switch to comfort, figuring I'm not going to burn that much battery power while I'm using heat from the coolant.
I'll update the original post with this as well.

The test was for 12 miles. Mainly 40 MPH driving hitting mostly of green lights.
- When I used ECO my ICE came on 3 times several days ago.
- Today using COMFORT it came on 1 time with the "WT" engine temp staying above the 114F threshold per my post.
 

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I think others have mentioned this as well. The reason seems to because it runs at a higher RPM to heat up the ICE/WT quickly so it can shut off. This is likely using less gas than running at a lower RPM for a longer period of time to heat up the ICE/WT. Try COMFORT. I thik your FAN ONLY setting is just pulling the heat out of the ICE/WT faster since the electric heaters are not running. I've never used FAN ONLY in these winter temps but I have used ECO and that is very different than my COMFORT testing this morning.
looks like you are right.

this morning, the 33-mile drive with FANS ONLY had the ICE come on 10-15 times (I didn't count). Seemed to use a lot of gas.

On the reverse drive this afternoon, I selected COMFORT (70F)/AUTO and the ice came on twice for 1 minute each and used .07 gal of gas. So, there is a definite difference. Because of COMFORT mode, I did not finish the drive on battery alone but think overall usage of gas was way less. The outside temp was 13F-16F.
 

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Discussion Starter #8 (Edited)
Because of COMFORT mode, I did not finish the drive on battery alone but think overall usage of gas was way less. The outside temp was 13F-16F.
The higher fan setting seems to use a lot of energy [update] and affects WT/engine temp. See my next post.[/update]. I generally run at fan level 1 or 2. I generally force the blower to dash_vents/feet (and to defrost/feet as needed). I think if you are in AUTO and then when you click the lower fan speed icon (smaller fan blades) that it shows the current fan speed that AUTO was using. Seems to be my experience.

From saghost here:
http://gm-volt.com/forum/showthread...lt-just-a-little-quieter.&p=114557#post114557
I happened to see this before I left for work this morning, and I had the DashDAQ set to show APM current already. After I got to work, I ran a double sweep, up and down. The results aren't perfectly consistant, but it should give a good idea. Car on, lights off, radio on, in fan only. There are six user adjustable fan speeds (and fan off.) The first number is from the sweep up, the second from back down - both APM current, so fan wattage should be the change multiplied by ~14 volts.

Fan off: 21/21
Speed 1: 23/22 - 21 watts more than fan off
Speed 2: 25/22 - 35 watts more than fan off
Speed 3: 26/24 - 56 watts more than fan off
Speed 4: 26/26 - 70 watts more than fan off
Speed 5: 29/28 - 105 watts more than fan off
Speed 6: 35/36 - 203 watts more than fan off

So you can see the fan at full speed is drawing about 200W on the 12V bus - a third of it in the last setting only.

Incidentally, for those wanting a radio off option, I was interested to note that using the center console power button made no measurable difference in APM current when the climate control was off.

[update] scottf200 - added XX watts more than fan off. sent pm to saghost letting him know asking if it was ok [/update]
 

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Discussion Starter #9
Using a ScanGuage this a.m. while it was 13F ambient temp out:
  • ICE came on after a couple minutes of leaving 55F garage and ran for 3 minutes (0.07gal) until "WT" water (engine) temp hit about 164F.
  • I noticed in my other vehicles that the Scangauge IA (intake air temp) would be very close to the ambient/outside air temp on my displays (Ford Exped, Honda Civic) BUT in the Volt I saw the the IA remain in the mid 40Fs ... remember the ambient outside temp was 13F. Perhaps I'm misreading this or is the Volt shutting some intake flap to help keep the ICE temp from dropping too fast.
  • "WT" dropped on my 12 mile trip to work to 123F and stayed there! Actually within a few miles of work I saw it go back up to 125F and 127F ... and the ICE was still OFF. In other words, I never saw it drop to 114F again where the ICE would turn back on. ... remember the ambient outside temp was 13F
My testing going home show similar results even tho it was 11F.

A little experimenting 2/3s the way home showed if I used AUTO (4 level fan speed resulting) then the "WT" water (engine) temp went to around 125F but if I used 2 level fan speed manually then WT temp would go to 134F. I even saw it climb from 125F to 134F when I switched to 2 level fan speed from AUTO/4 when I did the switch with 2 miles left coming home.
 

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Comfort mode definitely helps prevent the ICE from kicking in. At least with my unscientific tests :). It sounds like your tests are showing with a lower fan speed that the coolant is able to better retain its temperature. Which makes sense since less heat is being transferred to the cabin.

Today, using Eco both ways on 30 mile round trip, the ice kicked in a half dozen times each way Using Eco allows me to get home with a few miles of charge on cold days like today, but at the cost of the ICE turning on due to temp. Using comfort doesn't allow me to get home with charge, but i need to test if the ICE uses less gas in comfort than when the ICE turns on due to temps since the last few miles I have no charge left.
 

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Thanks Scott for posting your semi-scientific results. On my 6 degree drive home (7 miles) I had one long ICE run at the beginning and a short run at the end (compared with two long runs this morning).

Next question... if you precondition (in a warm garage) with Comfort selected and fan on 1 or 2, does it decrease the length of the initial ICE run?
 

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Discussion Starter #12 (Edited)
Next question... if you precondition (in a warm garage) with Comfort selected and fan on 1 or 2, does it decrease the length of the initial ICE run?
Interesting question. It seems as if you are asking if the ICE is warmed up some by the electric heaters running while in COMFORT. For example:

a) if your garage is normally 55F and you leave when it is 25F out then as soon as the car's "center stack" see you are outside and it hits 25F you will see the ICE run. The ICE then needs to go from 55F to ~160F before it quits (ie. ~3 minutes).

b) same situaiton as "a)" except by preheating doe sit change your ICE "WT" temp to say 95F from 55F as your garage normal temp. And if you leave when it is 25F out then as soon as the car's "center stack" see you are outside and it hits 25F you will see the ICE run. The ICE then needs to go from 95F to ~160F before it quits (ie. ~X.Y minutes).

I don't know. Curious. May not be much of a difference in time or gas I'm guessing. Well not to me but some of you folks are "gas anxiety" freaks <grin>.

I may experiment.

[update]
Experiment: 11:30pm 55F garage -- Full battery charge; CLIMATE; fan speed 2.
0 minutes - 55F WT 66IA -- WT = Water (engine) Temp

Precondition/remote_start - 1
5 minutes - 58F WT 66IA
10 minutes - 78F WT 67IA

Precondition/remote_start - 2
15 minutes - 82F WT 69IA
20 minutes - 95F WT 71IA

Conclusion: It would seem the initial ERDTLT would run a less time and use less gas because instead of going from 55F WT to ~160F it would start at 95F WT and go to ~160F ... but that is with two remote starts.
[/update]
 

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Makes sense to me - in comfort, the electric heater is warming the coolant more and the engine needs to run less. I just keep it at 72 auto / comfort most of the time, unless I can possibly stretch out the electric range enough to get home, With a $40 / month fixed electric rate for charging from DTE, I don't have an incentive to get home with more than 1 mile range.
 

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I tested Comfort mode today with the ambient @ 19°F. Yesterday it was 17°F so I think the two drive cycles are comparable.

I was shocked at how much difference there was between Fan Only and Comfort mode when the Engine is force to run for low ambient.

In Fan Only the engine ran ~ 30% of the time and cycled on and off about 6 times (maybe more as I did not log the number). In Comfort mode the engine turned on once at the start of the trip, ran for ~ 3 minutes and never turned on again. MPG was ~ 60 MPG on Fan Only and 193 MPG on Comfort mode. Trip length was 14.1 miles.

This does use a lot more battery so as long as you have enough to make the trip it does significantly reduce the engine run time. I did set the temperature to 65 °F and set the fan to low.
 

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Interesting question. It seems as if you are asking if the ICE is warmed up some by the electric heaters running while in COMFORT. For example:

a) if your garage is normally 55F and you leave when it is 25F out then as soon as the car's "center stack" see you are outside and it hits 25F you will see the ICE run. The ICE then needs to go from 55F to ~160F before it quits (ie. ~3 minutes).

b) same situaiton as "a)" except by preheating doe sit change your ICE "WT" temp to say 95F from 55F as your garage normal temp. And if you leave when it is 25F out then as soon as the car's "center stack" see you are outside and it hits 25F you will see the ICE run. The ICE then needs to go from 95F to ~160F before it quits (ie. ~X.Y minutes).

I don't know. Curious. May not be much of a difference in time or gas I'm guessing. Well not to me but some of you folks are "gas anxiety" freaks <grin>.

I may experiment.

[update]
Experiment: 11:30pm 55F garage -- Full battery charge; CLIMATE; fan speed 2.
0 minutes - 55F WT 66IA -- WT = Water (engine) Temp

Precondition/remote_start - 1
5 minutes - 58F WT 66IA
10 minutes - 78F WT 67IA

Precondition/remote_start - 2
15 minutes - 82F WT 69IA
20 minutes - 95F WT 71IA

Conclusion: It would seem the initial ERDTLT would run a less time and use less gas because instead of going from 55F WT to ~160F it would start at 95F WT and go to ~160F ... but that is with two remote starts.
[/update]
This is very interesting. It seems the electric heater is heating the engine block during the remote start. That second remote start is getting close to the threshold, too - a third remote start (not allowed) would push you past the initial ERDTLT cycle. Maybe if you let the car sit in the garage for a few minutes while on it'll keep heating the engine block?
 

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Mixed bag

I generally run in Fan-only and have recirculate on and fan speed set to off or lowest setting, do not have heated seats, pre-condition, twice if able. This morning I opened the garage door, got in the Volt, turned it on, then got out to clean my wife's windshield. It was VERY frozen, so took me a few minutes. I went in to tell her that it still had some ice on and to warm it up well before leaving. When I went back out to the garage the Volt's ICE was running "due to temperature". I stopped at a gas station (to buy gas for the snowblower) and the ICE came on at least a second time. I did not get on the freeway due to congestion (on the freeway) and noticed that the ICE never seemed to come back on even though I had no environmental heat on. The outside temp was 7 degrees F. The range did come down to 25 miles (it has been around 33 up to now). I could swear that even with the controls set to fan-only that I felt some heat. I did have to run the defroster for a short while early on.
 

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Discussion Starter #17
I generally run in Fan-only and have recirculate on and fan speed set to off or lowest setting, do not have heated seats, pre-condition, twice if able.
<snip>
The outside temp was 7 degrees F. The range did come down to 25 miles (it has been around 33 up to now). I could swear that even with the controls set to fan-only that I felt some heat.
I have not tested this with a temp measuring device but others have made comments that when in FAN mode it will still use waste heat from the ICE and provide heat.

The point of thread was that if you do use COMFORT that it will use the electric heaters. This will also "TRY" to keep the ICE temperature above the lower threshold of 114F and causing "Engine Running due to low temperature" ERDTLT a 2nd+ time. I suspect it is by design and the 'heat exchanger' is in play. Lot of subtle engineering things in our clever Volt's.
 

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[update]
Experiment: 11:30pm 55F garage -- Full battery charge; CLIMATE; fan speed 2.
0 minutes - 55F WT 66IA -- WT = Water (engine) Temp

Precondition/remote_start - 1
5 minutes - 58F WT 66IA
10 minutes - 78F WT 67IA

Precondition/remote_start - 2
15 minutes - 82F WT 69IA
20 minutes - 95F WT 71IA

Conclusion: It would seem the initial ERDTLT would run a less time and use less gas because instead of going from 55F WT to ~160F it would start at 95F WT and go to ~160F ... but that is with two remote starts.
[/update]
Are you preheating on 120 or 240? I tried a few times today to duplicate this in my 46F garage on 120 - first with a discharged battery last night and then with a charged one this morning. I'm not seeing any increase in the engine coolant temperature as reported by my DashDAQ. So the car has decided to do something else to confuse me. :)
 

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Interesting thread. Good work Scottf200 in collecting data and trying to figure out the best way to further optimize the VOLT. The car does have a lot of smarts to it and fun to figure out it's various levels of intelligence. Driving the VOLT continues to really make the conventional ICE cars seem so crude.
 

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I tried this yesterday (sub 24*) on short trips with a 3/4 charged battery, and it does seem to cut down on engine run time. Can't really guess what the battery impact was, but more experimenting is in order.

Seems like the ECO and Comfort buttons might be a bit opposite than what people might infer them to be, from an engine run stand point.

Can we guess this is probably cheaper than gas at this point??... unless one is on one of those crazy tiered baseload rates that some folks have posted.
 
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