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2013 Power output / regen not as much as others

10K views 102 replies 19 participants last post by  scottf200 
#1 · (Edited)
Okay, I think I'm going to have to do something about this after replying to the Maximum regen rate? thread. So as to not hijack that thread, I'm starting a new one. I think that is the correct thing to do protocol-wise.

Here's the scoop:

I bought a 2013 CPO Volt. This car was only the second Volt that I have ever touched and the first (and only) that I have ever driven so I don't exactly know what to expect. Volts are rare here but I did see one driving in Atlanta last week.

What follows here are pieces of information that I am hoping that someone knowledgeable with Volts might see a common thread and might know of a possible root cause. I'm sorry for it being long but I would hope that a complete summary would be best.

For reference, my other vehicles is a blown 6.2 4WD Silverado. My last car was a recently departed CTS V-Sport (wrecked while parked) which I have not replaced since I didn't drive it much once I got the Volt.

I purchased the Volt to be my daily driver to "save" my Silverado from grunt daily miles. For this, the Volt has been SUPERB! Electric driving is a pleasure and CS mode isn't bad.

The first point is that I think the battery is fine. I get a solid 30 to 40 miles on a charge, assuming good weather and no climate usage, and have seen a period of over 600 miles without any gas usage. My record is like 46 miles on a charge using 10.4 kWh.

I do use the car to drive out of town but am disappointed with CS fuel economy, averaging 24 to 28 MPG on premium gasoline. I did get caught in an area where premium was not available used had one tank of regular unleaded and quoting Mr Ripley, believe it or not, I got 34.x MPG on that tank. Engine seemed to perform fine but I did return to premium fuel and my mileage has since returned to the mid-20's. I could one could add "better MPG with regular than premium" to the wonky evidence.

One interesting point that could be a clue: Highly optimistic fuel consumption reporting. I have begun and ended several out-of-town trips by fueling up at my "favorite pump" with Shell premium, filling in the same manner, and have come to realize that the fuel measured in is considerably more than the car indicates using the Trip B display.

For example, my last trip covering 281 miles two weeks ago, my car indicates that I used 6.5 gallons but Mr Shell sold me 8.3xx gallons. I started with a full charge and recharged at my destination. I recorded on paper that 28.0 + 28.3 miles were on electricity thus leaving 224.7 miles on gas. According to the car, I got 34 MPG or so but calculated 27 MPG according to the pump.

This disappointment is compounded by the net cost being about the same as the pickup. 20 mpg at $2.00 per gallon versus 26 mpg at $2.80 per gallon. But okay, I have just lived with that, wondering about trying another tank of regular unleaded.

Another point is that I just had to put new brake pads on my car. The dealer said the hardware was fine and yet the CPO inspection said the brakes were good. I purchased the car at night after driving to another state and didn't give the brakes a real look over as they felt fine and no pulsation so I cannot confirm that.

The Maximum regen rate? thread really got me thinking. The peak regen I routinely see is -12 to -15 kW while in Low and if braking, no matter how hard, only increases to -17 kW, a number I see frequently while slowing.

Today I realized something else. No matter how hard I press the brake pedal, as soon as the brake lights come on, the MyGreenVolt application will "ding" at me which I believe means the mechanical brakes are engaged. In fact, it is not possible to brake without engaging the hydraulic brakes.

I have been reading more here on the site and see that the peak power output should be over 100 kW. I cannot get it to go over 59 kW power output under any circumstance, Drive or Low, Normal, Sport, Mountain or Hold modes.

I had always thought that Volt performed okay, but I would never say it was "fast." I haven't tried to clock any numbers but remember that other Volt I saw in Atlanta last week? When the light turned green, he left me behind like I was a turtle. The peak numbers seem to confirm that my Volt is slower than other Volts.

Driving up Alabamas modest hills requires full throttle most of the time and accelerating / passing up hill is impossible. Passing on two-lane roads requires lots of room. Back in the 80's, I had a Chrysler K car for a rental that seems to have about the same passing power... they both got around but the sweaty palm detector went off in both cases.

In exactly four months, I've put 6,459 miles on the car, 58.3% EV. How it drives hasn't changed one bit.

There are no check engine lights. I have pulled codes and there is nothing there. Fluid levels look fine. Fluid colors look fine.

My question is if anyone can see something in common with these issues?

The problem is that I can't go into a dealer and say "bad fuel economy" or "poor performance" without something to go on.

On top of that, I don't like the dealer (it's not my regular wonderful non-Volt dealer). For example, when I got the car, the battery coolant level was low and went to buy genuine GM 50-50 to fill and they said that I couldn't do that and quoted $500 to top it off saying it was "sealed for life system" and such. They also quoted $150 to replace the front-right turn signal bulb.

I did the top offs myself anyway without issue, put the Volt on the lift at my good dealer and they let me change the bulb, installed a VoltGrille and VoltPhone mount.

Also the day I got the car, I purchased four Pirelli P7 tires which have performed well, no tire wear, 40 to 41 psi.

Oh, I drove to Tennessee and had a discharged battery in Chattanooga. As left Chatty on IH 24, I remember about the grade up to Monteagle so I engaged Mountain Mode. The engine revved up a bit and I forgot about it until I reached the beginning of the grade, I would say about 45 minutes later.

I was wide open throttle the whole way up doing only 45 mph until Reduced Engine Power came up on the drivers display and dropped to 20 or 25 mph. The battery was fully discharged again; sadly, I did not note the battery level when I started up the grade. Thankfully the Pilot truck stop was in sight where I pulled in, let the car idle in MM for about a half hour while I ate. When I returned to the car, the charge then was only at 3 bars, but it was enough for me to continue my trip.

After the incident, I researched here regarding MM and had bookmarked a couple of threads. One Paging WOT, MM acceleration issue, BAD clearly indicates 80kW when the generator is operating and 110kW in the normal mode, which I fundamentally understand, two motors, one has to generate and such. However I clearly remember going up Monteagle seeing 59kW a number of times. (I see this number A LOT.)

Well, that is all of the information that I can think of. Is there anything else that I can add here?

I do like the car and it suits my needs well. My original idea was that if I liked the Gen 1, I'd later get a Gen 2, even though I have never seen one in person, but I like this car enough, I can see myself driving it for four or five years, assuming the capacitive touch controls and unresponsive touch screen don't drive me crazy. Actually, I wanted the car when it was first shown but since I didn't a local dealer that sold it, I never considered it until recently. And with the prices of the CPO Gen 1's, it was too much of a temptation.

Thanks in advance for any thoughts or ideas that might help me get this car up to speed, no pun intended.
 
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#2 ·
I wanted to add something about the previous owner and just realized something....

I do know something about the previous owner. For one thing, their address was still in the GPS and Google StreetView shows my car in their garage. It was showing 131 MPG average having run right at 75% of time on the electric power. Interior was immaculate save for a leftover perfume sample between the drivers seat and the console. So, the car was plugged in, garaged and well treated.

The car was in a minor bump showing up on the Carfax. I contacted the dealer that had done the repair only a few weeks earlier. The body shop guy said that "a lady had backed into a post" and that no other damage was done. He said it only required a rear bumper cover, rear reflector and the requisite paint and install. No biggie there but it was a negotiating point and helped me get another $1,000 off!

This is where it gets VERY interesting.... I just calculated this....

Since the car had 39k miles on it, and thus I know that 9,750 miles were on gasoline. OnStar was also able to tell me that the car had consumed a total of 265 gallons of gas.

That equates to 36.792 MPG !!!!!

SOOOO, THIS CAR HAS SEEN BETTER MILEAGE THAN I AM EXPERIENCING!!!

Or is that because the car is reporting less fuel used? Arrgghhh, I don't know!

I would consider fuel quality, but I have purchased fuel in enough places, including ethanol-free premium unleaded at Midnite Oil in Chattanooga at the foot of Signal Mountain.

Okay, thinking cap is getting a working right now...
 
#3 ·
My biggest question out of all of that is why did you have to have the brakes replaced? It sounds like the brakes are engaged in some fashioned even without any pedal used. Your regen rate should be far higher than your getting. I usually see a max regen rate in the 50kw range when stopping from freeway speeds, and maximum power reaches 114kw when accelerating. This is also on a '13.

Mountain mode should build the battery from a minimum SOC to 50% or so in about 20 minutes. Having had to run yours for 45 should have been more than sufficient to climb any grade. 30 minutes on MM at idle should have had you returning with the 5 bars or so to indicate half of a battery on the GOM, and an engine off since it won't charge more than about 45%.

As for the mismatched pump/trip fuel calculations, I would definitely keep an eye on those. You mentioned it's a CPO, did you also get the onstar set up with a smart phone? If so, I would look at the car status page that shows battery and fuel range. If I recall, the fuel range shows gallons remaining. I have the free basic package so don't remember offhand since I lost that functionality. I would check to see how many gallons it's reporting at fill up, and again at the next fill up and see if it jives with what the car shows.

Sounds like there are a number of issues at play with this vehicle, and with the CPO warranty in effect as well as remaining Voltec/Powertrain I would definitely have it checked out. If nothing else, the very low regen and low acceleration power output are definitely a concern, with the lower power output possibly putting the car into a safety risk since it will have difficulty maneuvering in an emergency situation at this point should you need max power for some reason.
 
#5 ·
Thanks for your reply.

My biggest question out of all of that is why did you have to have the brakes replaced? It sounds like the brakes are engaged in some fashioned even without any pedal used. Your regen rate should be far higher than your getting. I usually see a max regen rate in the 50kw range when stopping from freeway speeds, and maximum power reaches 114kw when accelerating. This is also on a '13.
The warning tab was making contact, squealing every time I barely touched the brakes. Surfaces were fine, no pulsation. Just worn pads.

Mountain mode should build the battery from a minimum SOC to 50% or so in about 20 minutes. Having had to run yours for 45 should have been more than sufficient to climb any grade. 30 minutes on MM at idle should have had you returning with the 5 bars or so to indicate half of a battery on the GOM, and an engine off since it won't charge more than about 45%.
If I turn on the car, engage Mountain Mode, and assuming the state of charge is low enough, the engine will come on and the yellow bar will come up to about 1/4 the way up the indicator so it is charging. However at the truck stop the engine was most certainly still running. And I eat very slow... 30 minute is very conservative.

As for the mismatched pump/trip fuel calculations, I would definitely keep an eye on those. You mentioned it's a CPO, did you also get the onstar set up with a smart phone? If so, I would look at the car status page that shows battery and fuel range. If I recall, the fuel range shows gallons remaining. I have the free basic package so don't remember offhand since I lost that functionality. I would check to see how many gallons it's reporting at fill up, and again at the next fill up and see if it jives with what the car shows.
Yes, I have been monitoring the fuel consumption as I realized the discrepancy very quickly. The phone application seems to report the gallons about as accurately as I could expect.

Also the fuel gauge in the instrument display and the low fuel warning seem to be about right. A recent trip to Mississippi, the low fuel light came on and I put something like 8.5 gallons in minutes later.

Sounds like there are a number of issues at play with this vehicle, and with the CPO warranty in effect as well as remaining Voltec/Powertrain I would definitely have it checked out. If nothing else, the very low regen and low acceleration power output are definitely a concern, with the lower power output possibly putting the car into a safety risk since it will have difficulty maneuvering in an emergency situation at this point should you need max power for some reason.
I always need max power (grin).

And, yes, I'm convinced that "something" is wrong, but I would like to approach the dealership with some real evidence. If I were going to my usual dealer, this wouldn't be an issue, but the others, well, you know the rest of that story.

Thanks again!
 
#7 ·
That has certainly been in the back of my mind. That's one reason that I initially dismissed the MPG issues waiting until the tires have some miles on them, but now at least 10% of their usable life has rolled on by and would think that initial mileage losses would have been minimized by now.

Also consider that my EV range is very good, often exceeding the rating. I don't really count highway driving and cold days as they are not optimal for EV operation. In fact, it's going to be cold again over the next few mornings here as we're supposed to get back down into the 50s. (Why did I put up my coats!?)

However on nice days around town, I frequently reach 4 miles per kWh which seems like a good bar to reach.

On top of that, the car seems to roll forever, although just still a bit short of perpetual motion. haha

Actually, if my car really isn't regenerating as much as it should, I wonder how many miles I'm going to get per charge?!

I'm sure in the grand scheme of things there was some loss from maximum / optimal, but I cannot see how they are affecting the other systems or economy while in charge sustaining mode.

Thanks for your reply!
 
#6 ·
How close a match are the new tires to the original? Revs per mile and weight? Certainly, you're paying some penalty in mileage there, but it sounds like a lot more stuff going on.

Have you checked for a dragging emergency brake, or overheated rotors after a drive confirming the friction brakes are working overtime, perhaps dragging?
 
#8 ·
The tires are the same rated size as per the door jam. They were purchased at Sams Club but they won't install tires in sizes that are not on the sticker.

As for revs per mile or weight, I did not compare at the time except for a visual inspection. However I'm checking the web sites right now:

Neither factory web site had full information but Tirerack does:

Text Green Font Line Parallel


It seems that the Pirillis are 1 pound heavier and 2/10ths of an inch taller and a bit more contact patch. Close enough for my book, and I am satisfied with their handling and quietness.

As for dragging components, yes, that I one thing that I did check. While I had it on the lift at my regular dealership, I checked for a dragging caliper but couldn't feel anything. I haven't checked using an IR thermometer but honestly, I'm not expecting anything unusual.

Even the dealer when they changed the pads said that the hardware was fine, clean and working correctly. I specifically request the check as I suspected a dragging caliper, as well.

As for the parking brake, I have tested it but frankly, I don't like an electric "emergency" system.

But then again, I'm not suspecting brake drag, especially when my EV range is so good.

Thanks for your reply!
 
#9 ·
The tires are the same rated size as per the door jam. They were purchased at Sams Club but they won't install tires in sizes that are not on the sticker.

As for revs per mile or weight, I did not compare at the time except for a visual inspection. However I'm checking the web sites right now:

Neither factory web site had full information but Tirerack does:

View attachment 134401

It seems that the Pirillis are 1 pound heavier and 2/10ths of an inch taller and a bit more contact patch. Close enough for my book, and I am satisfied with their handling and quietness.

As for dragging components, yes, that I one thing that I did check. While I had it on the lift at my regular dealership, I checked for a dragging caliper but couldn't feel anything. I haven't checked using an IR thermometer but honestly, I'm not expecting anything unusual.

Even the dealer when they changed the pads said that the hardware was fine, clean and working correctly. I specifically request the check as I suspected a dragging caliper, as well.

As for the parking brake, I have tested it but frankly, I don't like an electric "emergency" system.

But then again, I'm not suspecting brake drag, especially when my EV range is so good.

Thanks for your reply!
Sam's club tires. That's the culprit (at least one of them). Give us the the brand and the model name of the tire. My Goodyear assurance tires were great at low rolling resistance, but grippiness was lacking. I switched to Yokohama Ascends and my mileage dropped (i.m lucky to get 30 miles of EV range on a good day) but I also stopped driving like a grandpa and more like Jeff Gordon.

Secondly, I suspect you are driving the car like a jackrabbit, probably at or above the speed limit. That kills range.

best techniques to increase your ev range and gas mileage, slow down, drive like a grandpa, and avoid the brakes or regen as much as possible while being safe. The brake lights will turn on as soon as you press the brake pedal. but that doesn't mean the friction brakes are engaged.

To prove to yourself that a brake isn't dragging, drive for a long stint (3-5 miles at high speed where you don't have to brake much, regen in L until you are almost to a stop, then stop with the brakes. Get out and carefully touch the calipers. If they are all cold, then you are fine, but if one is warmer than another, you have a brake pad dragging.
 
#11 · (Edited)
o prove to yourself that a brake isn't dragging, drive for a long stint (3-5 miles at high speed where you don't have to brake much, regen in L until you are almost to a stop, then stop with the brakes. Get out and carefully touch the calipers. If they are all cold, then you are fine, but if one is warmer than another, you have a brake pad dragging.
I just ran (drove) up the street to check something. I just got up to 50 mph and put it into Low. The car began regenerating at -11 kW and kept counting -10, -9, -8, -7 and then straight to 0.5 kW at about 35 mph at which point the car just kept rolling for about a mile and a half until I had to stop for a traffic light. This segment of road had a light decline but not much. I've ridden it on a bicycle and it didn't go downhill enough! haha

Anyhow, I tried a few more times, the car discontinue regen in Low at the slower speeds, but the point is variable at some point between 30 and 40 mph.

I am assuming that it should regen all the way to a stop... Is that correct?

Oh, one more question about Volts.

If I'm in Drive and let off the throttle, a 'normal' car will decelerate using engine braking.

Should a Volt do the same thing?

My car feels like it is coasting in neutral or with the clutch disengaged.
 
#14 ·
Oh, I drove to Tennessee and had a discharged battery in Chattanooga. As left Chatty on IH 24, I remember about the grade up to Monteagle so I engaged Mountain Mode. The engine revved up a bit and I forgot about it until I reached the beginning of the grade, I would say about 45 minutes later.

I was wide open throttle the whole way up doing only 45 mph until Reduced Engine Power came up on the drivers display and dropped to 20 or 25 mph. The battery was fully discharged again; sadly, I did not note the battery level when I started up the grade. Thankfully the Pilot truck stop was in sight where I pulled in, let the car idle in MM for about a half hour while I ate. When I returned to the car, the charge then was only at 3 bars, but it was enough for me to continue my trip.
Sounds like your Mountain Mode is not performing as expected. As I mentioned in the other thread, the youtube video Self Charging Volt shows MM recharging a fully depleted 2012 Volt’s 16 kWh battery to the MM-maintained level in 15 minutes using 0.36 gallons of gas while the car is parked. When the MM-maintained soc level is reached, since the car is not moving, the engine shuts off. I’ve experienced this with my 2012 Volt. If you are parked while recharging with MM, when the battery is recharged to the MM-level, the ICE shuts off.

The 2013 battery is slightly larger and might require a few more minutes and use a little more gas, but if you were idling at a truck stop using MM to recharge, and it took longer than ~20 minutes (did you note the amount of Gas Used?), it sounds like there’s something wrong with the MGA generator output or generator-to-battery charging system.

Note, too, that the Gen 1 Volt continues to be propelled by the electric motor in Extended Range mode. Loosely speaking, a Gen 1's gas mileage, i.e., MPGcs, is the distance you can drive on the amount of power provided to the primary traction motor by burning 1 gallon of gas in the generator. If you are generating less electricity per gallon of gas than expected, your gas mileage will suffer. 24-28 mpg is less than expected. Perhaps your generator is not performing as expected.
 
#17 ·
The dealership that I prefer and actually do trust (really good people) are not setup to do warranty service on Volts. I drive 40 miles there, right past the local Chevy dealer which, well, let's just say that I get shivers thinking about going there. However I guess I don't have a choice and will stop by tomorrow and make an appointment.

I've already printed the MyGreenVolt screen shot to show essentially no net regeneration.

Any other pieces of information that I should pass on to them past demonstrating the engine "gauge" quitting regeneration ?
 
#18 ·
Definitely something wrong. in MM, you should see the yellow bar indicating engine operation, usually about 1/3 or so filled, but you should also see green in the regen indicating that it's adding to the battery to build the SOC.

When braking, friction brakes should only be applied when hard braking or speeds below 5mph. This was why I questioned the need for brakes so early. My '13 has over 100K miles and they look almost new. It seems to be that if you needed brakes, its likely been an issue for a while (possibly since new?) that the blended brake system isn't working as designed. I'm curious to add though, when accelerating at max power, what is the yellow bar reading? It should be near or at the max but I suspect you're only seeing it go to about 2/3 or maybe 3/4 since you indicated it's only applying about 60-70kw of power.

In response, you should see regen to about a complete stop when braking. Even light braking should give 10kw of regen with harder braking upwards of 30 to 40+. I probably don't brake as gently as I could, but I still begin to brake within a reasonable distance (4-500 feet from a stop) and even from 45-50 can frequently see regen in the 15+ range when coming down from 50mph or so.

Strictly speaking from my own personal experience, the electric portion of the car should take care of pretty much any driving conditions including braking to such a low speed the mechanical friction brakes are only needed to come to a final stop. It sounds like you definitely need to have a service tech see the car, and if necessary go on a ride along so you can demonstrate these odd behaviors. Definitely something not right!
 
#19 ·
Definitely something wrong. in MM, you should see the yellow bar indicating engine operation, usually about 1/3 or so filled, but you should also see green in the regen indicating that it's adding to the battery to build the SOC.
I would say the yellow graph on the right is 1/4 the way up, but I wouldn't argue against 1/3 the way up. As for the green part going down, there is a one pixel slice.

When braking, friction brakes should only be applied when hard braking or speeds below 5mph. This was why I questioned the need for brakes so early. My '13 has over 100K miles and they look almost new. It seems to be that if you needed brakes, its likely been an issue for a while (possibly since new?) that the blended brake system isn't working as designed. I'm curious to add though, when accelerating at max power, what is the yellow bar reading? It should be near or at the max but I suspect you're only seeing it go to about 2/3 or maybe 3/4 since you indicated it's only applying about 60-70kw of power.
At full throttle, it usually goes straight to 59 kW and the left yellow bar going about half-way up.

In response, you should see regen to about a complete stop when braking. Even light braking should give 10kw of regen with harder braking upwards of 30 to 40+. I probably don't brake as gently as I could, but I still begin to brake within a reasonable distance (4-500 feet from a stop) and even from 45-50 can frequently see regen in the 15+ range when coming down from 50mph or so.
If I'm in Low, I see regen up to about -18 kW in the green for a few moments and then it drops to 0.5 kW or 1.0 kW in the yellow.

If I'm in Drive, I see regen up to about -5 kW in the green for a few moments and then it drops to 0.5 kW or 1.0 kW in the yellow.

That's about the simplest way I can describe it. How long it generates depends on the starting speed but I can say that 100% of the time, if I start braking under 25 MPH, I don't see any regen, which I figured was normal since there was less inertia due to the slower speeds.

Strictly speaking from my own personal experience, the electric portion of the car should take care of pretty much any driving conditions including braking to such a low speed the mechanical friction brakes are only needed to come to a final stop. It sounds like you definitely need to have a service tech see the car, and if necessary go on a ride along so you can demonstrate these odd behaviors. Definitely something not right!
I always thought the brakes felt funny is comparison with a regular car, but I figured it was not being used to the technology since I have never driven another Volt. Makes me wonder if I should have driven down to Florida to see one before buying.

Thinking about how to describe the brake feel... I would say for the first 25% of brake pedal travel nothing happens then suddenly it grabs and releases until you reach about 50% brake pedal travel.
 
#20 ·
I never noticed the brakes felt any different from a regular car. In fact, it's difficult for me to even tell the difference between regen and friction brakes in the Volt. By your description of "nothing for 25% of brake pedal" that tells me that regen is definitely not working right. I notice definite regen at the top of the brake pedal with progressively more regen the more I press. The sudden grabbing indicates the friction brakes are engaging, though not sure on why they release until you hit 50% brake travel other than that would be about where they would normally start to engage under harder braking. I suspect once this is all situated and working properly you will be very pleased with how the brakes work when operating correctly.

I don't really want to speculate anything just yet, but it almost sounds like something in the inverter went wonky but I'd think that should set a SES light. If that's the case, it's definitely covered by the Voltec warranty. I can sympathize with your dealership option. I'm in somewhat the same situation as there is only one Chevy dealership in town with a Volt tech, and my experience with them (as well as others with non Volt vehicles) is less than even mediocre. Unfortunately my next option involves a drive to LA which is about 100 miles south. I guess they know they're the only game in town and use that to their advantage. Definitely keep us posted on what the outcome of this situation is.
 
#21 ·
I would be most concerned with the rather low kW readings, and some of the other issues (like poor MPGcs and friction brakes engaging sooner than required) could be related.

When you step on it, the Volt should be able to pump out over 100kW from the battery to the traction motor (MGB). And max regen should be ~55kW (which happens to be the rating of the generator MGA). If you are not seeing this, I think there there is definitely something wrong. I regularly see 100+ kW draws and 50kW+ regens on my 2013 Volt .. You can say I am a spirited driver.
 
#22 ·
One thing that concerns me is your discrepancy of fuel consumed to fuel added. My 14 Volt was never more than .1 or .2 gallons different. I would try different gas station.
 
#31 ·
I agree. My cars have always been very close to what the drivers information center reports. Or at least close enough.

As for gas stations, while I have a favorite Shell station, I've been all over.

Now consider this. As I stated in my first post, I got into a situation where I could not find premium unleaded and went ahead an put in a tank of regular remembering that some people had success with it. The car ran fine, and while I heard no audible preignition, I cannot discount events the sensor picked up that I didn't.

The interesting point is that I got noticeably better economy in CS mode confirmed with my calculator. It was definitely over 34 mpg.

If this were a flex fuel vehicle, I would wonder if the module didn't detect the correct rating or when the vehicle starts up the ICE that it didn't correctly pick the right table. As I recall there is one for premium fuel and one for lower octane.

But then again, why the poor MPG when that is a completely different system than the electric drive?

(Visualize someone banging their head against a concrete wall)

I keep pondering what could possibly be in common, what could be in common that wouldn't generate an error code.

How could the car think the power output is proportional to the inputs? For example, in a modern automatic transmission, there transmission controller compares input shaft RPM and output shaft RPM versus what ratio is selected to know if there is slippage.

I'd better quit thinking. My brain is starting hurt. Or at least something between my ears is hurting.
 
#27 ·
I have only used Mountain Mode three times "for real" beyond testing purposes.

(1) Engaged in Chattanooga with zero bars before going up Monteagle 45 minutes later and after the Reduced Power message, stopped at the truck stop and left it in MM while eating

(2) Engaged in Knoxville with zero bars before going up to Clingmans Dome TN and after the Reduced Power message, left it in MM while at the top.

(3) Engaged while parked for about an hour while eating in a small town in Northern Alabama after getting the Reduced Power message after going up a hill with zero bars and left it in MM for the rest of the drive.
 
#24 ·
It sounds like an accelerator problem to me.

If the car thinks the accelerator is even slightly depressed, it disables regeneration on the brake pedal and goes straight to friction.

If the car thinks the accelerator is slightly depressed, you'll have less regen in both Low and Drive.

I'm not sure how a depressed accelerator can figure into the lower maximum power, but if the car thinks it is depressed because of a problem with the sensor or pedal, that same problem might keep it from thinking the pedal is pressed down all the way, too.

Have a close look at the pedal, make sure there aren't mats or anything else in its way. If everything looks normal, try lifting the pedal with your foot while you're slowing down and see if it matters.
 
#28 ·
Good thinking but I had already checked the sensor range with a scan tool and it reports something like 3% to 100%.

I had experimented with Sport mode but when I realized that I could reach 59 kW in both modes, I kinda ruled it out, as well.
 
#26 ·
He should still get more kw showing when he floors it even if something is dragging. It almost sounds as if one of your motors isn't working or the clutches are malfunctioning. Odd that it wouldn't show a code or anything.
 
#29 ·
I agree, but there definitely no codes for anything and have never seen a check engine light. I had to turn the car on a few times to even find it!

Also what is weird is the number 59 kW. That doesn't correspond to anything. If I recall correctly, one motor is 55 kW and the other is 110 kW.

In MyGreenVolt, it shows both motors working while under wide open throttle.
 
#30 ·
I would say your evidence for something wrong that you can take to the dealer is right there. That 59kW.

For kicks and giggles I'd be interested in what your 0-60 time is. Sounds like it could be way slower if you are in fact getting only 59kW.
 
#50 ·
Okay, I've got a number using Torque Pro on an Android phone communicating via Bluetooth to the OBD2 adapter.

It was blistering cold outside as we are down in the 50s and I had to run the defroster since it was a little drizzly. I have a friend with a long, smooth paved drive to his house on a farm that I have used it to diagnose vehicle before. (At least this time his wife couldn't complain about engine noise!) While the driveway was wet but I never spun a tire and traction control never kicked in.

Turns out that my car is truly slower than it feels. Perhaps being so low to the ground versus my truck gave me the impression that it was quicker than it really is.

I did three runs to 60 mph: 12.389, 12.667 and 12.501 seconds.

Soooo, that seems in line with the other numbers.

However one interesting thing did occur. I did see 61kW pop up on the display and stay there for a couple of seconds. So "59" itself isn't a hard point. Maybe because I had the climate control system on because doesn't that get added into the power numbers?

Anyhow, question answered and another piece of puzzle is found. Now where to put it!?
 
#32 ·
You know, I think this might be a good excuse to get my stopwatch out.

The other Volt I saw in Atlanta was DEFINITELY quicker than mine.

And, to update everyone, I have an appointment for Tuesday the 23rd and she said they will need the car for at least the rest of the week.

On my way there, I used the Interstate in electric mode. The on-ramp has a bit of a hill on it and can say that it is about as fast as an S-10 Blazer to 70 MPH.

I'm putting a charge on the car right now because I've been driving the wheels off it. Did over 100 miles on electric yesterday alone. After I fix something for lunch, I may put that stopwatch to good use...

And, to all, thanks for your replies! All these little bits of info is useful and helps me think through what could be going on.
 
#34 ·
No. While I do have various scan tools and a Bluetooth reader, I do not believe in leaving them plugged as I do not want to add any unnecessary data on the buses.

I had a Malibu Maxx that bought a ScanGauge II for it and knew such devices could cause unexpected consequences when, just by plugging it in, caused several solenoids to activate with the engine off and key out.

Good question.
 
#35 ·
OK. Let’s boil down the facts to define the problem. In essence, you don’t have excessive drag because your efficiency in CD is good (4.4 miles per kWh, for example). Things causing drag such as brakes, tires, alignment, etc. go away.

Historically, the car in CS mode averaged 36.8 mpg, slightly less than advertised. Maybe the previous owner had a heavy foot on the go pedal, maybe not. Your experience is worse; 34 mpg going by what the car declares; 27 mpg if you use the gas pump figure. You may have a heavy foot on the go pedal, the car is lying, the gas station pump may not be calibrated. We have too few data points to accurately define efficiency in CS mode. At this point it is just an indicator.

BUT…

The car seems to lack power in CS mode and seems to be limited in regeneration when observing the driver’s information display. We do know that in CS mode available power is not as great as when in CD mode. That is by design. However, the OP sees a maximum of 59 kW. IIRC, in CS mode the maximum should be 80 kW – someone correct that figure if need be.

Monteagle's 4–6% grade seems steep. I drove in CS mode west toward Bolder City from Hoover Dam on US 93 with CC set at 65 mph and the Volt produced the power needed without any curtailment over about 7 miles. I mention that as the ICE was wailing like a banshee. I haven’t been able to find a published gradient for that section of road. Your experience in driving from Chattanooga to Monteagle seems suspicious.

It would be nice if Customer Care monitoring this forum would offer to help the OP with this problem.
 
#37 ·
OK. Let’s boil down the facts to define the problem. In essence, you don’t have excessive drag because your efficiency in CD is good (4.4 miles per kWh, for example). Things causing drag such as brakes, tires, alignment, etc. go away.
Agreed. 4.0 miles per kWh is easy enough to hit.

Historically, the car in CS mode averaged 36.8 mpg, slightly less than advertised. Maybe the previous owner had a heavy foot on the go pedal, maybe not. Your experience is worse; 34 mpg going by what the car declares; 27 mpg if you use the gas pump figure. You may have a heavy foot on the go pedal, the car is lying, the gas station pump may not be calibrated. We have too few data points to accurately define efficiency in CS mode. At this point it is just an indicator.
I only consider fuel economy on long trips, such as 100+ of CS mode. Short trips vary wayyy too much.

Easy driver. Usually exceed ratings. In my pickup, I exceed the highway rating by 2 or 3 mpg most of the time. Even towing a 16,500 lb trailer in the company truck (Duramax), I get 11 mpg and I see others getting 7 to 8 mpg.

I have data on 13 trips, all but one showing in the 20s using pump data, all showing 30s using car data. (One in the 30s using pump data and that anomaly was after using a tank of regular unleaded.)



The car seems to lack power in CS mode and seems to be limited in regeneration when observing the driver’s information display. We do know that in CS mode available power is not as great as when in CD mode. That is by design. However, the OP sees a maximum of 59 kW. IIRC, in CS mode the maximum should be 80 kW – someone correct that figure if need be.
Your numbers seem logical as one motor gets reversed into generation duties.

I see a maximum of 59 kW in both CD and CS modes.

Monteagle's 4–6% grade seems steep. I drove in CS mode west toward Bolder City from Hoover Dam on US 93 with CC set at 65 mph and the Volt produced the power needed without any curtailment over about 7 miles. I mention that as the ICE was wailing like a banshee. I haven’t been able to find a published gradient for that section of road. Your experience in driving from Chattanooga to Monteagle seems suspicious.
Maybe this is a clue: I can barely hear the ICE. I can feel it buzz but overall, I think the little engine is very quiet. Definitely quieter than the engine in my truck by a long shot. (Well, especially when the ICE doesn't need to run!)

When I bought the car, I was curious about the RPM range and used a basic Actron scan tool to watch it for a little while. I didn't document it but most of the time, the engine stayed below 2000 rpm and cannot recall it ever exceeding 3000 rpm.

Under what condition could I get the ICE to reach maximum RPM ? I'm thinking about putting it into MM and drive up a 1.5 long hill. I wonder if the root generation problem is that the ICE isn't being instructed to go to the highest RPM range.
 
#36 ·
Just for a comparison, I have a 2013 in the Shenandoah Valley of VA and I just clicked over 50k miles this week.
Assuming fairly ideal conditions of temperature, wind, and so forth.....
  • Generally 39mpg running the REX (Range Extender) at even highway speeds of 70-75 mph
  • Full power that I can get from just the REX tops out at 54kWh
  • 39-41 miles BEST EV range (37 is typical)
  • Running on battery tops out at 110-114 kWh
  • My Regen tops out at 59kWh and seems to dump to just hydraulic brakes at about 5-7mph.
  • Regen alone (car in "L") will not bring my car to a stop even on a flat, at 5-7mph regen stops and the car just rolls
  • 0-60 in about 7.7 sec

My car has absolutely NO problem climbing and accelerating on the 10% grades of route 33 through Shenandoah National Park while on battery, and will also "hold it's own" though not accelerate if I'm doing the same drive on just the REX although the REX howls like a banshee when I push it that hard.
 
#38 ·
Considering the range of problems, could this possibly be a defective 12 volt battery situation ?

I was thinking that the electronics are driving from the 12 volt system, would be instructing the inverter as to how much power to produce, how much to generate, etc.

My guess is that the battery is original but I haven't looked at it.

The only anomaly beyond drivability issues is that the back door push buttons don't work very reliably. However the rear hatch has never failed to release. I replaced the button battery in all three of my remotes because one was weak.
 
#43 ·
I second sherpa's comments.
It's almost like you're running in Propulsion Power Reduced (PPR) mode, but that should have a message on screen and a MIL accompanying it. Very strange.



No. If the car is on and functioning, it's on and the 12V is only along for the ride getting a trickle charge. HV+APM are providing power the vehicle during regular operations. If those die, the car would not drive.
OP would also be seeing lots of strange error messages and MILs on startup and I haven't seen reference to anything of that sort.
 
#39 ·
There are cellphone apps that will log 0-60 times. Or cheap race computers that will do it. They start when the car moves.
Charge the car up, powerbrake it, hit START, and let 'er rip. Should be in the 8.x second area IIRC. If it's 60kW, it will be about 12++ seconds.

60kW is the max regen rate. 109-113kW is the max WOT rate.

It will generate full regen rate in drive or low with the brake. Take the car up to 75mph and brake assertively but not to the ABS (pedal pulsing) level. It should stay frozen at 60kW for awhile since you are past max regen.

The ICE engine is only 84hp so 63kW peak once fully warmed up.
 
#45 ·
I don't believe the car is driveable in service mode, it just lets the computers fully boot for testing purposes.
But you could try turning it on and off in service mode and see if it makes a difference.

Service Only Mode
This power mode is available for service and diagnostics, and to verify the proper operation of the malfunction indicator lamp as may be required for emission inspection purposes. With the vehicle off, and the brake pedal not applied, pressing and holding the POWER button for more than five seconds will place the vehicle in Service Only Mode. The instruments and audio systems will operate as they do in ON/RUN, but the vehicle will not be able to be driven. The propulsion system will not start in Service Only Mode. Push the button again to turn the vehicle off.
Notice: Service Only Mode will discharge the 12‐volt battery. Do not use Service Only Mode for an extended period, or the vehicle may not start.
Not sure what tr represents, but it looks like just regular service, recalls and tire replacement to me.
However, if one of those recalls involved HPCM2 it may have messed up the software that controls the hybrid components. Reflashing that might fix it.
 
#48 ·
If it's a bad tune, that should easily be picked up when an MDI is connected. My understanding is that all modern GM ECU's maintain a record of all flashes performed. This has been a huge topic of concern since some people were flashing a tune, screwed something up, reflashed the GM approved tune and took in for warranty repair which was denied since a record of past tunes was present and indicated a non-approved flash.
I sure hope that is not the case, especially since this isn't my normal dealership.

On the other hand, I know something of the original owner and have my doubts.

That said, I guess it would be nice if a reflash fixes it but I have my doubts there and one would think there are sufficient checksums in place.

The funny part is that the car does run, I'm driving it most every day. It hasn't hiccuped, belched or, well, anything else.
 
#47 ·
If it's a bad tune, that should easily be picked up when an MDI is connected. My understanding is that all modern GM ECU's maintain a record of all flashes performed. This has been a huge topic of concern since some people were flashing a tune, screwed something up, reflashed the GM approved tune and took in for warranty repair which was denied since a record of past tunes was present and indicated a non-approved flash.
 
#49 ·
I'd bet it's just something with the existing tune that went wonky. Unfortunately it seems even though a reflash frequently just writes the same program that was there before, it seems to take care of a lot of issues when done unless it's a hardware failure of some sort. I always question how something thats been burned to a ROM can get corrupt or altered to cause undesired operation but apparently it happens as several members have had control modules reprogrammed with the same programming that was present before and problems cleared up.

It's like trying to wrap my head around a CD/DVD going bad because the written portion somehow became corrupt. It doesn't work in my head how that can happen, but plenty of evidence on here suggests otherwise.
 
#51 · (Edited)
I'd bet it's just something with the existing tune that went wonky. Unfortunately it seems even though a reflash frequently just writes the same program that was there before, it seems to take care of a lot of issues when done unless it's a hardware failure of some sort. I always question how something thats been burned to a ROM can get corrupt or altered to cause undesired operation but apparently it happens as several members have had control modules reprogrammed with the same programming that was present before and problems cleared up.
Or maybe the stored values / parameters / data cache gets cleared and starting from scratch solves the problem.

It's a shame that we can't disconnect the battery to reset everything like we could in the early days of fuel injection. I won a Maxima in a radio station contest in the 80s and it couldn't handle changes in altitude, but disconnect the battery for 30 seconds, reconnect and drive off and it would relearn the altitude via the MAP sensor the instant the key was turned on / before the engine started and it would be fine again. Later, I added a momentary normally-closed switch to the ground of the CPU to make that process easier.

It's like trying to wrap my head around a CD/DVD going bad because the written portion somehow became corrupt. It doesn't work in my head how that can happen, but plenty of evidence on here suggests otherwise.
Ah, but the substrate can go bad and change the "pits" that make up the data. Burned discs with a purple color are usually have an organic substrate that can deteriorate in the presence of UV light / sunlight. I have accidentally left discs near a window and you can see the change in color. Once I had a gem clip on a disc that left a ghost image after a few weeks.

(holding up a Dr Pepper)

Here's to a reflash fixing the problem!
 
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