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If it is “normal “ why does my neighbor’s 2016 Volt NOT HAVE the problem? I have personally test drove my neighbors 2016 Volt and found no such noise. Car manufacturers have a long history of denying a problem and chalking it up to “normal operation” to avoid repairing the car. Before purchasing I read every car review available and no one mentioned the so-called “normal” noise. I guess car reviewers from Alex Dykes (Alex on Autos) to Consumer Reports must of missed the “normal” backfire noise.

2016 Summit White Premier
 

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Watch the video at 1:19 to 1:21 there are two small flashes and and a bigger flash coming from the exhaust pipe. Audio times perfectly with the flashes probably water vapour. I'm convinced its exhaust related.
^^^ This ^^^
 

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I have a 2016 Chevy Volt with about 3,000 miles on it.

When I accelerate in all-gas mode, I hear a click / bang noise coming from the rear passenger side of the car and I'm trying to figure out what it is.

It's easier if you hear it for yourself so I made a video with more details (see link)[video]https://vimeo.com/177954038[/video]

The noise doesn't happen in electric mode...only while using gas.

Anyone else notice this?

I have a friend with a Volt and tried to reproduce the noise using the same conditions but never could.

Thanks,
Scott
Well I don't know what it sounds like from outside the car, but the description and occurrences are exactly the same.
 

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Hey everyone! We've noticed quite a few of you have been concerned about this 'backfire noise.' We took the opportunity to get in touch with our technical engineering team and want to assure you all that this is considered normal operation.

If anybody has additional questions/concerns, please feel free to send us a private message. We're always here and happy to help.

All the best,

Lauren E.
Chevrolet Customer Care
What a crock. They all don't do it. So yes, please explain this "normal" noise.
 

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What a crock. They all don't do it. So yes, please explain this "normal" noise.
I'm taking mine in soon for a rough cold idle issue and the backfire problem that I've posted about in my own thread. I already asked about the backfire at my recall appointment, and they said it was normal. When I take it in again, I'm going to ask if I can discuss it with a mechanic in greater detail and have them explain to me why it happens and see if I can insist that they do some tuning or whatever needs to be done to make it not happen. The transition from EV to ICE would be so incredibly smooth if it weren't for that backfire noise every time...
 

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I'm taking mine in soon for a rough cold idle issue and the backfire problem that I've posted about in my own thread. I already asked about the backfire at my recall appointment, and they said it was normal. When I take it in again, I'm going to ask if I can discuss it with a mechanic in greater detail and have them explain to me why it happens and see if I can insist that they do some tuning or whatever needs to be done to make it not happen. The transition from EV to ICE would be so incredibly smooth if it weren't for that backfire noise every time...
Agreed. A complete crock. I've had my 2016 for 10.5 months and over 14k miles. Never had a backfire.

Any other dealers nearby?

Best,
Rick
 

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Agreed. A complete crock. I've had my 2016 for 10.5 months and over 14k miles. Never had a backfire.

Any other dealers nearby?

Best,
Rick
Well, I could take it to the dealer where I bought it instead of the dealer by my house, but that's about a 45 minute drive for me and I don't feel like going that far. I'd like to be able to get decent service at the dealer by my house to avoid having to drive so far...
 

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Hey everyone! We've noticed quite a few of you have been concerned about this 'backfire noise.' We took the opportunity to get in touch with our technical engineering team and want to assure you all that this is considered normal operation.

Engine Misfire – 2017 Chevrolet Volt

Engine Misfire During Engine Maintenance Mode (EMM) – 2016 Chevrolet Volt

Well, I suppose this depends on your definition of 'backfire noise' since there are currently documented issues of engine misfire conditions for both the 2016 & 2017 Volts at the above links including the fix of a software update in order to correct...
 

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Contrary to Chevrolet’s pronouncement that this backfire noise is no big deal (normal operation), in fact, this is a pronounced irritating noise. I’ve had passengers riding in my car comment on the noise and surprised it happened in a brand new car. I for one would not have purchased the car knowing this noise is considered “normal operation”. I find it hard to believe the Volt Engineering Team would design a car to work in this manner. If Chevrolet continues to claim this is “normal operation” then potential buyers should be forewarned. I suggest a “Sticky” be added for this discussion reading, “Chevrolet Concludes Backfire Noise is Normal Operation (in Hold Mode) for 2016-2017 Volts, BUYER BEWARE.”

It is insufficient to simply state this is “normal operation”. Chevrolet Customer Care please provide a technical explanation, which includes a discussion as to why some 2016-2017 Volts have the backfire, and others don’t.
 

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Minor update, but I think my backfire issue has resolved due to extended ICE usage. My commute varies but I've averaged 10-15 miles of ICE usage through the fall. Now that winter is here, I've used about 14-20 miles of gas now due to increased ECO HVAC usage.

I've noticed both when accelerating hard from full stop in HOLD and in charge depleted mode that the backfire sound doesn't happen anymore. I never took my car to the dealer for this issue so nothing has been done. Only thing different is possibly using better gasoline from Shell (I had used a supermarket branded gasoline previously). The gas still showed ethanol blend (I forget what %) but I figured all Shell stations got their fuel from the same Top Tier rated source at Shell Corporate.

Does the ICE need breaking in? With better quality fuel? I've now put 1000 gas miles on my ICE, wonder if everyone else with the backfire issue has less than 1000 gas miles.

I'm going to cross post this in another thread to spread awareness.

Gen 2 Volt, VIN #11955
 

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Excess gas can wreck your catalytic converter over time. I recommend not leaving it, I would regard this as one of those cases where it is actually a more serious issue that it sounds!
 

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Thanks for the update and potential solution. According to the Chevrolet Customer Care Advisor, the backfire is "normal operation". If the backfire noise is no longer present, does that mean the car is not working properly (he says sarcastically). Volt owners with this backfire issue are seeking a solution but it appears Chevrolet has walked away from the problem.

2016-Volt Premier
10/2015 Build Date
 

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Until they give us a detailed description of what causes the noise and why some Volts don't make the noise, I'm not letting it go. My friend's Gen 2 doesn't do it and I don't want mine to >_> if his doesn't make the noise, there's gotta be a way to make mine not make the noise. They're nearly identical.
 

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Excess gas can wreck your catalytic converter over time. I recommend not leaving it, I would regard this as one of those cases where it is actually a more serious issue that it sounds!
What do you mean by "excess" gas....?

Thanks,
Rick
 

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What do you mean by "excess" gas....?

Thanks,
Rick
Probably unburnt fuel in the exhaust. That can cause backfiring as it passes through the catalytic converter, which can reach temperatures well above those needed to ignite gasoline, especially if it has lost octane from sitting too long. If the Volt ECU shuts off the ignition before the fuel, it can leak a little fuel into the exhaust which gets ignited next time the engine is started. That's my theory as to why it backfires. I can't answer why some of them do and some don't, however. And it's the only hybrid vehicle I know of that does so.
 

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What do you mean by "excess" gas....?

Thanks,
Rick
One part of the catalytic system consists of an 'oxidising' part which effectively burns up all the unburnt hydrocarbons getting through the engine.

It's very important not to send too much unburned stuff down the pipe, else this gets very hot, too hot in-fact and it starts craking the cat matrix, and ultimately may burning off the catalyst from the matrix.

It already runs really hot in normal operation, let alone abnormal operation.

This is why there are loads of warnings, if not a shut down, if your lambda sensor stops working. You basically can't run an oxidising catalyst without stroke-by-stroke fuel control (i.e. you can't really run one with a carburettor, hence everything is fuel injected now because you need that level of control over the exhaust gases).

As soon as the lambda sensor detects too little oxygen in the exhaust, the system figures there must be an excess of HCs going through, so will back off the injection rate to avoid burning the cat up.

(It can't run too much oxygen either, else the engine will start pinking and/or 'dieseling'.)

It actually needs oxygen in the stream to oxidise with the HC too, though, so you can see it is a very fine balance adjusted by fuel injection versus throttle position/air flow. The lambda sensor is the component that measures if the correct (or slightly over) 'stoichiometric' mix of oxygen to fuel is going through, and the cat cleans up any excess.

The stuff in an oxidising cat is basically the same as those catalytic heaters you can get for running off LPG/butane. There's no combustion, the little heater matrix catalyses the fuel with the oxygen. It isn't 'burning' but it gets just as hot. In fact hotter, because it is more efficient.

If you have unburned fuel in the exhaust you have way too much HCs running in it and you will soon find you are failing exhaust emissions because of excess HCs.
 

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Learning about all this excess gas causing backfire and ramifications of it are very helpful. I'll keep an eye out and keep testing for the backfire. My Volt still hasn't made the sound again. Though it hasn't warmed up above 50F this whole week. I only recall the backfire sound back during 50F+ weather.
 

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Learning about all this excess gas causing backfire and ramifications of it are very helpful. I'll keep an eye out and keep testing for the backfire. My Volt still hasn't made the sound again. Though it hasn't warmed up above 50F this whole week. I only recall the backfire sound back during 50F+ weather.
Same with mine...I haven't noticed it at all now that Chicago has blessed us with a taste of the south pole. That further confirms the suspicion that it's a bit of unburnt gas in the exhaust...the exhaust cools off faster when the engine shuts off in the cold (obviously) so it isn't hot enough to flash ignite the unburnt gas when it gets pushed through (probably) the cat when the engine starts again.
 
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