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Discussion Starter · #1 ·
I need some help please! I have a 2011 Volt with 125K miles on it. Recently, it decided to run primarily on gas and not the battery, despite having anywhere for 32-27 ev miles available. What needs to be done to get the vehicle to go back to running on the battery first, before switching to the gas engine like it used to.

I've taken it to the dealership and they tell me there is nothing wrong and now its in another shop and they are trying to figure it out, but they don't know what's wrong with it either. They suggested I use all the gas in the tank because it might be old. Well its been running on gas so the gas isn't old, but the old gas just stirs it, doesn't make the engine continually run on gas anyway. So I need some help if anyone knows what's going on.

Thanks Debbie
 

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Likely it's Fuel Maintenance Mode (FMM). Before now when was the last time you used gas and how old is the gas?

6 gallons of gas from 6 months ago mixed with a gallon of new gas is still old. Consider running it down to an estimated 20 miles range and add 3-5 gallons rather than a full tank. If you rarely use gas, a full tank will eventually age-out and the car will want to run on that until it's gone. Some who rarely use the gas engine will only keep a few gallons in the tank so when it ages out, they are only burning a few gallons rather than a whole tank.
 
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Discussion Starter · #3 ·
Likely it's Fuel Maintenance Mode (FMM). Before now when was the last time you used gas and how old is the gas?

6 gallons of gas from 6 months ago mixed with a gallon of new gas is still old. Consider running it down to an estimated 20 miles range and add 3-5 gallons rather than a full tank. If you rarely use gas, a full tank will eventually age-out and the car will want to run on that until it's gone. Some who rarely use the gas engine will only keep a few gallons in the tank so when it ages out, they are only burning a few gallons rather than a whole tank.
I have been using the gas because it hasn’t been going on battery and I’ve used several tanks. How do you get it out of fuel maintenance mode? I can try running it down again and only putting a gallon or so in it but I’ve sort of already done that
 

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I have been using the gas because it hasn’t been going on battery and I’ve used several tanks. How do you get it out of fuel maintenance mode? I can try running it down again and only putting a gallon or so in it but I’ve sort of already done that
If you've already run the tank down to near empty and put a few gallons of fresh gas in, FMM should stop automatically.
 

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What is the temperature when the engine is running? What are the driving conditions? Is when accelerating rapidly or going up a hill? Does the cluster indicate Propulsion Power Reduced (or any other messages)?

If it is FMM, be sure to shut off the car when refueling - I have heard the car may not register the fact you added fresh fuel if the vehicle is still turned on when refueling.
 

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Discussion Starter · #6 ·
If you've already run the tank down to near empty and put a few gallons of fresh gas in, FMM should stop automatically.
Any other ideas as to what might be the problem and how do I turn off the fuel maintenance mode in case the sensor is bad and needs to be changed. How do you change or check the sensor for that because maybe the sensor is bad.
 

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There is no sensor, just a computer algorithm that keeps track of the age of the fuel. Can only be turned off by burning some or most of the old gas and then adding fresh fuel.
 

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My 2011 has been doing this occasionally as well, as I’ve pointed out in other threads. Not FMM or ERDTT but the cold weather seems to be involved. It will be fully charged with 22-24 miles on the guessometer. One interesting note:! The green bars on the range gismo seem to leave one open at the top now. Anyway back to description. The car is garaged in a heated garage. Ambient temp never below 40-45. ERDTT is triggered at 26 Fahrenheit in the 2011’s. The behavior varies, but Sunday morning the outside temp was 35. Pulled out of the garage, ICE starts and runs for 8 miles. Then it shuts off, reverts to EV operation and range shows 20 with maybe 2-3 bars missing from the top. Another interesting note about the missing bar after full charge. I can unplug the EVSE wait 10 seconds, plug back in and it will charge for another 10-20 minutes. At this point the missing bar might be back and it’s green all the way to the top. 10 years old car, 10 years old battery. I might just pre emptive make an appointment at Green Tec for there $6,000 swap out.
 

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One possibility Debbie would be the switch which indicates the hood latch is closed. These Volts once started on battery will switch to gas when the hood latch is pulled. Apparently this was designed in to give technicians a quick diagnostic access to the engine running. So if the computer thinks the hood is open it starts the engine.
 

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One possibility Debbie would be the switch which indicates the hood latch is closed. These Volts once started on battery will switch to gas when the hood latch is pulled. Apparently this was designed in to give technicians a quick diagnostic access to the engine running. So if the computer thinks the hood is open it starts the engine.
This is possible, but wouldn’t it indicate hood open on the display? Also, with the hood unlatched, the engine only runs when stopped. Once the car is in motion, the engine stops until a stop sign or red light starts it up again.
 

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Discussion Starter · #11 ·
My 2011 has been doing this occasionally as well, as I’ve pointed out in other threads. Not FMM or ERDTT but the cold weather seems to be involved. It will be fully charged with 22-24 miles on the guessometer. One interesting note:! The green bars on the range gismo seem to leave one open at the top now. Anyway back to description. The car is garaged in a heated garage. Ambient temp never below 40-45. ERDTT is triggered at 26 Fahrenheit in the 2011’s. The behavior varies, but Sunday morning the outside temp was 35. Pulled out of the garage, ICE starts and runs for 8 miles. Then it shuts off, reverts to EV operation and range shows 20 with maybe 2-3 bars missing from the top. Another interesting note about the missing bar after full charge. I can unplug the EVSE wait 10 seconds, plug back in and it will charge for another 10-20 minutes. At this point the missing bar might be back and it’s green all the way to the top. 10 years old car, 10 years old battery. I might just pre emptive make an appointment at Green Tec for there $6,000 swap out.
It sounds very similar to what my car has been doing. I have about 28-32 on the ev battery when charged. I see one dark bar at the top now to when fully charged. but.... I'm in Southern California and it doesn't get colder than the low 40's here, maybe, maybe high 30's in the canyons but were not in the canyon. My issue with swapping it out at greentec is that its 6K for a nickel battery that is expected to last 3 years but warrantees for only 18 months. We shouldn't have to swap out the battery with 75-80% capacity left is where I'm coming from with that. If that is the case I want to know if that is the deal meaning that the battery won't run anymore if only 75% capacity.
 

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Discussion Starter · #12 ·
This is possible, but wouldn’t it indicate hood open on the display? Also, with the hood unlatched, the engine only runs when stopped. Once the car is in motion, the engine stops until a stop sign or red light starts it up again.
Very interesting.
 

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Also, with the hood unlatched, the engine only runs when stopped. Once the car is in motion, the engine stops until a stop sign or red light starts it up again.
When I first got the car I was looking under the hood and did not drop it from high enough to completely latch it. I couldn't figure out while the engine was running when I turned on the car, lol. As I recall, it was running while I drove the car, but it was 10 years ago...
 

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It sounds very similar to what my car has been doing. I have about 28-32 on the ev battery when charged. I see one dark bar at the top now to when fully charged. but.... I'm in Southern California and it doesn't get colder than the low 40's here, maybe, maybe high 30's in the canyons but were not in the canyon. My issue with swapping it out at greentec is that its 6K for a nickel battery that is expected to last 3 years but warrantees for only 18 months. We shouldn't have to swap out the battery with 75-80% capacity left is where I'm coming from with that. If that is the case I want to know if that is the deal meaning that the battery won't run anymore if only 75% capacity.
It wouldn't get swapped for a nickel cadmium battery, but used modules the same you have now (lithium), but with the voltages still reading as "good". As for as longevity, the only guarantee would be whatever the warranty is, since these are already old cells. Personally I wouldn't put that amount of money into it unless the battery was brand new, which isn't an option.
 
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For the point where it won't run anymore, you will eventually see a service message on the driver's display. Others here have reported abnormal behavior prior to the Service Message being triggered. I don't think anyone has had an issue with linear, gradual degradation. It's failures in 1 or more individual cells which drops the overall pack voltage to an unacceptable level, triggering the error.
 

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My 2011 with 113K is behaving similar to to what Debbie H. is seeing and nearly identical to what caronjeff is seeing. I'm in Michigan and it seems somewhat related to the cold weather. MyGreenVolt doesn't show any cells that are consistently low, although I must admit that I'm still trying to understand that app's screens. Sometimes I get DTC's and sometimes I don't, with similar behavior in both cases. Battery heater seems to be working, per MGV. ICE is getting about 24mpg. It doesn't run all of the time; fires up before moving the car, but sometimes stops at red lights. Also doesn't run sometimes at low speed even though the HV battery is still grayed out and DIC indicated running on ICE.
Wish I had advice or info for the OP, but I'm just another confused Gen I owner running mostly on ICE. I'll update if I learn anything.
Thanks to all who participate!
 

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It doesn't run all of the time; fires up before moving the car, but sometimes stops at red lights. Also doesn't run sometimes at low speed even though the HV battery is still grayed out and DIC indicated running on ICE.
In most cases. the gas engine acts as a generator, not a car mover. Unless the battery needs electricity (for the electric motors, A/C heat, radio, lights, etc., the gas engine does not need to run. That's why there's a disconnect for you. A gas engine typically runs all the time, whether the car is moving or not. Not the case with the Volt. Also why the engine does not vroom, vroom rev with the gas pedal. Instead, if the battery needs electricity, the gasoline-powered 1.4L generator will fire up, make some electricity and then shut down again. This can happen while sitting at a stoplight or while moving.
 

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In most cases. the gas engine acts as a generator, not a car mover. Unless the battery needs electricity (for the electric motors, A/C heat, radio, lights, etc., the gas engine does not need to run. That's why there's a disconnect for you. A gas engine typically runs all the time, whether the car is moving or not. Not the case with the Volt. Also why the engine does not vroom, vroom rev with the gas pedal. Instead, if the battery needs electricity, the gasoline-powered 1.4L generator will fire up, make some electricity and then shut down again. This can happen while sitting at a stoplight or while moving.
Yes, thanks Steverino, but I already understand the basic concepts that you are explaining here.
The thing I don't understand is: Why is the ICE running when there is a fully charged HV battery, while there are no codes being recorded? Battery temperature is around 40-50 degrees, HV battery voltage is around 4.00 volts per cell, with no obvious bad cells or big voltage differentials according to the MGV app. I understand that the HV battery is probably degraded and that range should be expected to decrease, but it is often providing very little range at all, with a fully charged battery. In fact, the display often shows ICE use only, even when it is actually running exclusively off of the HV battery at brief moments. So it doesn't seem to be a case of "loss of isolation", where the main relay inside the battery case disconnects the HV battery totally for electrical safety. And it also doesn't seem to be a case where the software is preventing any HV battery use to protect the battery from harming itself. It's indeed using the HV battery for propulsion, but only minimally.
There seems to be a big increase lately in reports on this forum of these symptoms for older Gen I Volts. I'm adding my voice to the chorus, in hopes that we'll eventually find some insight within the community as to why this non-normal behavior is occurring. It seems like a software error specific to aging batteries that are still capable of propulsion, being (almost entirely, but not completely) prevented from doing their job. It is certainly different from the normal synergy between the HV battery and the ICE that long-term owners recognize and understand, and that you describe above.
So, I agree with what you describe as normal operation of the ICE as a generator, but I'm pretty certain that these symptoms fall outside of those normal (as designed) ICE/battery propulsion behaviors. Something weird is happening to a growing number of early Gen I Volts, according to what I've experienced and what I've read from others.

Thanks again for your thoughts. No offense intended. I just think your explanation doesn't apply to this recent behavior that many of us are experiencing.
 

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To follow up on SBachmans thoughts, yes there’s a common thread here. Older Volts in cold/cool weather which immediately or almost immediately fire up the ice after start even with a fully charged battery. My intuition would tell me that the computer inputs from the battery status indicate a portion of the battery to be out of the prescribed tolerance range. Weather it’s a single low cell, multiple cells or a section, something is telling the computer to switch on ICE. Maybe the battery is fine but the mechanism which measures it is faulty. I’ve been concerned that this is in slow failure and eventually the car won’t work anymore, but maybe not? Maybe this is just something we live with and becomes expected in winter. As Debbie noted the typical Chevy dealer shop will be little to no help on this. The original GM engineering team is probably long gone to bigger and better, so insight from the top is probably non existent. The test will be someone just does a pre emptive battery swap maybe?
 

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This is from Eric on the Volt Redux Facebook page in regards to this issue.

Yes mine does the NON-ERDTT engine running in moderate cold temps too. Fairly often. It has the do with the latest software update that was the cell balancing update. The car runs the ICE when it feels it needs to so that it stresses the battery less, or something like that. It pretty much happens to all older Volts that have had the latest dealer installed update.
 
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