GM Volt Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
OK, here's a question for all of you out there who have driven both models like me. My old Volt was a 13 model. When the ICE came on, it was absolutely a non-issue - I would see it on the dash display, and might even hear it unless I was cruising on the highway. But never, ever, -not once- did it ever have the same experience that my new 17 model has. Today was the first time it has run on ICE for me so far. It came on while I was cruising at 75 on the highway (with the cruise on as well). When it came on, I did notice it immediately - not because of any noise (because I couldn't hear the engine on the new one), but I also felt constant very slight surging as I was going down the road. This feeling did not stop the entire way home, so it was not just related to the highway driving. In trying to describe what I was feeling, I would characterize it as kind of like an engine that had a bad spark plug or something which would cause it to miss or something - you'd get an uneven delivery rather than smooth consistent power. I was just wondering if others have ever noticed this? Or if there are others out there who have driven both generations like me, and noticed anything tremendously different like this? My car has very few miles on it since I just got it a few days ago, and very few miles driving under gas. I can say that the test drive car I drove actually went on the ICE as well while I was driving it, and I never noticed it. So I'm wondering if there might be something not quite right with mine? Anyone have any similar experience or thoughts?
 

·
Registered
Joined
·
2,336 Posts
Have you tired performing a search of these forums using the made-up terminology 'chuggle' yet!?:confused:

P.S. Whatever you do please don't urban dictionary this very poorly-chosen false term!:rolleyes:
 

·
Administrator
Joined
·
20,024 Posts
I believe there is a software fix for this. Yes, "chuggle" is the term being applied to this surging condition.
 

·
Registered
Joined
·
1,511 Posts
One would think that since the "chuggle" was discovered in 2016, it would not be present in any 2017 models. What am I missing?
 

·
Registered
Joined
·
695 Posts
I have a 2016 Volt built in October 2015. I asked my dealer about the "chuggle" issue, and he told me that my engine was not included in the technical bulletin. I wouldn't think any 2017 models would be affected either.

However, at highway speeds, I notice some "surge" in the drivetrain. Essentially, I find it to be more like the transmission has shifted gears or has a slight hesitation from time to time. This "surge" is not regular or constant, but is noticeable from time to time.

I believe this is related to the drivetrain, but it is not a hardware or software issue. See these two articles on the Gen 2 Volt's drivetrain.

http://www.greencarreports.com/news/1096942_2016-chevrolet-volt-powertrain-how-it-works-in-electric-hybrid-modes

http://www.greencarcongress.com/2015/04/20150423-voltec.html

The Gen 2 Volt has 4 modes of operation in extended range mode. In the high range-extended mode, the ICE is continuously seeking the most efficient point of operation. Sometimes this means it is operating at high power and both driving the car and generating electricity. At other times, it is driving the car and using electricity from the battery.

I did a mathematical model of this transmission, and in the high range-extended mode, the speeds of Motor A and Motor B can be modulated by the power electronics to control the speed of the ICE.

Now we have the ICE, which tries to operate in an Atkinson cycle, but might change from this configuration if more power is demanded. Also, the ICE has external exhaust gas recirculation, which is used to improve efficiency during part load operation. So this engine is constantly changing its load, speed, valve timing, inlet oxygen content, etc. to give the best efficiency.

I believe the "surge" that you are experiencing is related to the changing parameters in the engine and transmission as the system continuously searches for the optimum point of operation.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #6
This all sounds logical and plausible even. Could even be true, but I figure that it won't hurt to check with the dealer just to see whether my car would be included in that. I suspect I already know the answer which will be NO because it was built after that October date. But I don't know that for sure. Assuming all that you said is true, and it's normal operation for the car, it's still not a great feeling from the "seat of the pants". Almost makes it feel like the car is having trouble running and gives you the uneasy feeling that it might quit on you at any moment. I can't imagine that GM engineering would settle for that. Especially because, like me, it would unnerve a lot of buyers. Now, with that said, I can and will live with it if need be. But I am going to check it out first before I decide that it's "just the way it is." I had only one problem with my '13 in the 36,000 miles I put on it. And that related to the RKE (remote keyless entry). At about 30,000 miles, it started giving me fits not recognizing that the fob was in the car. I replaced batteries in both fobs, took it to the dealer, they replaced batteries and said it was low battery. I knew that was horse pucky, but I accepted it and went on. Within the week it began doing it again and before I traded the car in, it got to the point where you had about a 50/50 shot as to whether it would start up or not when you got in it. Even refused to unlock a few times, so I began carrying both fobs. My workaround was that if it didn't start, I'd press the unlock button or the remote start button on the fob, and then magically it would decide "oh I guess the fob is in here!" and it would start. Just a PITA to have to drag it out of my pocket most of the time. But at least that car's ICE was smooth as silk!
 

·
Registered
Joined
·
695 Posts
This all sounds logical and plausible even. Could even be true, but I figure that it won't hurt to check with the dealer just to see whether my car would be included in that. I suspect I already know the answer which will be NO because it was built after that October date. But I don't know that for sure. Assuming all that you said is true, and it's normal operation for the car, it's still not a great feeling from the "seat of the pants". Almost makes it feel like the car is having trouble running and gives you the uneasy feeling that it might quit on you at any moment. I can't imagine that GM engineering would settle for that. Especially because, like me, it would unnerve a lot of buyers. Now, with that said, I can and will live with it if need be. But I am going to check it out first before I decide that it's "just the way it is."
Let us know what you find out. There may be some improved software that could even out these transitions, however, that may well have an effect on the EPA rating, which I'm sure GM wants to keep at a maximum.
 
1 - 7 of 7 Posts
Top