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I had my EMM this week after six weeks without firing up the ICE. This has happened many before since my daily driving is typically covered by the Volt's 53 mile EV range. But his EMM burned 0.07 gallons instead of the usual 0.03 gallons, and a long time. Luckily, this was on a 19 mile drive home. The EMM accounted for 2.8 miles, but I think the Volt drove 10 miles during the EMM. I was mostly driving highways at 50-55mph, but there's actually a couple of stoplights on this highway. I watched the power flow display and the engine kept charging the battery even at the stoplight. But it must be running at very low RPMs since most of the energy required to move the car was being provided by the battery not the engine.

I wonder what RPM the e-CVT sets the engine to during EMM? I wonder why this EMM lasted so long?
 

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0.07 gallons is my normal EMM burn. I just wish ERDTT, which usually burns more fuel, would reset the EMM timer.
 

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Here's a guess. It must be colder even in Texas and since the EMM is not only to circulate the fluids (which is how it is usually described) but to remove any condensation in the oil etc., in colder weather it takes longer to do that. I'm a little surprized it doesn't take longer as I heard years back that BMW reported that to fully do the job (warm up engine, fully purge it etc.) takes 45 minutes. I've not had an EMM yet as once a month I need to use engine on a trip to a few towns over during the round trip so don't have experience with that (or the other).
 

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Discussion Starter #4
...But it must be running at very low RPMs since most of the energy required to move the car was being provided by the battery not the engine.

I wonder what RPM the e-CVT sets the engine to during EMM?
It must also be a very low kw value being generated. Maybe 5kw????
 

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I’m never in a rush when my EMM messages appear and I’m 99% ev around town, so to avoid the need to record gas miles when I’m not on vacation, I usually sit with my 2012 Volt parked on my driveway for the brief time it takes to run the EMM. That gives me time to glance at various numbers on the displays, including the energy usage screen’s Gas Used numbers.

Yes, following the EMM, my Gas Used is usually at 0.03 gallons, and on rare occasions, 0.07 gallons. What I have noticed at least once is that the meter ticks over to 0.03 a measurable amount of time before the EMM comes to an end. I really don’t know if that means the engine then continues to burn gas and the EMM ends before the process that would produce an increase in the Gas Used reading happens (an additional 0.03-0.04 gallons is not much gas; how precisely is gas consumption measured?). Perhaps that’s the last of the gas consumption, and then MGA continues to spin the engine to lubricate what needs to be lubricated every so often. Perhaps, depending on the time of year (environmental conditions) the maintenance requires running the engine a bit longer and thus consumes that additional gas...
 

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0.03 to 0.07 gallons may be enough to circulate fluids, lubricate the internal engine parts but it is not enough fuel/time to fully warm up the oil in the engine, drive out any moisture. I normally run my Volt for at least 10 minutes / 10 miles at highway speed to get the engine coolant, indirectly the engine oil, to full operating temperature. I consider the engine coolant fully warmed up when equilibrium is reached at between 185F and 205F, depending on the engine load and ambient air temperature. Even then I am not 100% certain I have fully warming up the Volt's engine having used 0.2 - 0.3 gallons of fuel.
 

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0.03 to 0.07 gallons may be enough to circulate fluids, lubricate the internal engine parts but it is not enough fuel/time to fully warm up the oil in the engine, drive out any moisture. I normally run my Volt for at least 10 minutes / 10 miles at highway speed to get the engine coolant, indirectly the engine oil, to full operating temperature. I consider the engine coolant fully warmed up when equilibrium is reached at between 185F and 205F, depending on the engine load and ambient air temperature. Even then I am not 100% certain I have fully warming up the Volt's engine having used 0.2 - 0.3 gallons of fuel.
This.

I have my doubts on EMM actually getting the oil up to temp. In fact, in cold temps I can guarantee 0.07 gal is probably just getting the coolant up to a normal temp then stopping things shortly after that.

From other engines, in light-ish driving, to get the oil up to temp (key variable here) you're typically looking at ~3-4 times as long as it takes the get the coolant up to normal operating range. In the Volt, since it's got a high thermal efficiency with high compression ratio, it can take as long as 5-8 minutes of reasonable load to get the coolant up to temp (in cold weather, warm weather is about half this). Based on that, I'd say the oil is just getting up to a warm temp ~15-25 mins in on a normal drive at reasonable load. If you're sitting at a bunch of stoplights, completely discount that time since the engine will actually cool down during that time.

I'm betting GM choose to optimize gas efficiency over burning off water in the oil during EMM. And realistically, it'd take "a lot" of water in the oil to really cause an issue, so I guess GM felt it wasn't enough to always push a prolonged EMM.


But I do think that people who primarily only use the ICE during EMM for long periods of time should generally get the ICE fully up to temp for 20+ minutes on a regular schedule. In the cold, where I'm more worried about condensation in the oil, and I can benefit from the ICE waste heat, I usually run the ICE during my ~30 min commute once every 2-3 weeks. That should be enough to evaporate most the water in the oil IMO.
 

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I had my EMM this week after six weeks without firing up the ICE. This has happened many before since my daily driving is typically covered by the Volt's 53 mile EV range. But his EMM burned 0.07 gallons instead of the usual 0.03 gallons, and a long time.
Is that not the next measurable unit of fuel after 0.03? Mine seems to count about 4 oz measures of fuel. I've never seen 0.05 used for example, kist 0.03, 0.06, 0.10, 0.13, 0.16 etc and the difference between 0.03 on the meter and 0.06 might be only a tablespoon of fuel, not a nearly doubling.
 

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so what warms up the volt faster moving or standing still ? ( on a cold day )

I find it takes a little longer to run the test by not moving but takes less gas

and more credit for EV miles if you are playing that game.
 

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so what warms up the volt faster moving or standing still ? ( on a cold day )

I find it takes a little longer to run the test by not moving but takes less gas

and more credit for EV miles if you are playing that game.
It depends whether the Volt's gas engine is running because the lithium battery is exhausted; or if the Volt is running in Hold or Mountain Mode or else the gas engine is running due to Engine Running Due to Temperature (ERDTT). When the gas engine is running for other than ERDTT cold weather conditions the Volt typically shuts off the gas engine at traffic signals or if the Volt is not otherwise moving. When ERDTT is activated the Volt's gas engine will continue to run, even when the Volt is stopped, until the engine coolant has reached ~150-160F. Then the Volt will cycle the gas engine on and off to maintain the engine coolant between 120F and 140F to ensure there is heat for the passenger cabin. Over the short term, local driving, ERDTT may use more fuel than Hold Mode but as you drive further EDTT will use less fuel (until the Volt's battery charge is exhausted.) A 60 mile one way highway trip in cold weather is probably beyond the Volt's cold weather battery range by ~10 - 15 miles. For part of the trip, once the battery charge is depleted, you will end up using some gas but less gas than if you had just driven the entire 60 miles on gas.
 

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Every month during the first week of the month, I put mine in hold mode and drive the ~6 mile trip to the store on ICE because I like to be in control of when it switches over and how long the ICE runs. I like to run mine the full 6 miles just to be sure it gets up to temp. Then at the end of my "ownership year" in October, I'll run it on ICE until the tank is empty and do my yearly fill up. It's a control thing I guess. ;)

Mike
 

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As far as I remember, mine have all been .03 gallons, and all on EV. Maybe that's enough to warm the coolant, but certainly not long enough for the oil. I keep a close watch on the Temps on my Jaguar, and the coolant is up to normal in 2 or 3 miles, but the oil takes eight to twelve minutes. Of course, it does have a 8 1/2 quart crankcase and a large oil cooler.
 

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so what warms up the volt faster moving or standing still ? ( on a cold day )

I find it takes a little longer to run the test by not moving but takes less gas

and more credit for EV miles if you are playing that game.
That's 'cause us with 2012s, without hold mode, use an invocation of CS mode to do EMM and ERDTT. That's why we get the ICE revving in response to demand, etc. For the later Volts, those cycles are different and don't actually become propulsion power; it just kinda runs at idle and as a result burns less fuel, but wastefully, instead of using it to at least go somewhere.
 
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