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'16 Volt backfiring?

32K views 115 replies 35 participants last post by  dannycamps 
#1 ·
I've noticed that fairly frequently my Volt makes a noise resemblant to backfiring when the engine starts. It seems to happen more at low speeds and less at speeds of 40MPH or higher. Right as the ICE starts, I can usually hear a pop or two coming from the rear of the vehicle that sounds a bit like somebody slapping the muffler with a plastic ruler.

My vehicle went for about a year without much ICE use by the previous owner; it made me put fresh gas in through Fuel Maintenance Mode right after I bought it a few weeks ago. Could that have something to do with it? Or is it something completely different from a backfire?

It seems odd that a nearly brand-new fuel injected engine would backfire but that's definitely what it sounds like.
 
#34 ·
I took my Volt in last Thursday for diagnostics and they told me I needed new spark plugs. They tried to get them in overnight, but they didn't arrive on time, so I took it in again this past Tuesday and got a loaner for the day. They replaced the plugs and did a 29-point inspection, and I haven't noticed a rough idle since then. It still feels a bit rougher when it first starts but it doesn't shake the car or sputter/cough anymore. I'm not entirely sure why a one-year-old car with 4000 miles needed new plugs but it seems to have fixed that issue.

The unfortunate part is that it still backfires...
 
#37 · (Edited)
I think I found another video online of the backfire from a stop on ICE. Not 100% sure since owner didn't mention when they switched from EV to ICE. At 15:34 is when I think the sound can be heard:

https://youtu.be/4JfTWlKHF6s?t=933

FYI, it's also a great video for demonstrating the same rattle I have behind the OnStar/light panel in the header. Also, it demonstrates the loud warnings to get from both lane departure and collision warning:

Collision warning: https://youtu.be/4JfTWlKHF6s?t=447
Lane departure: https://youtu.be/4JfTWlKHF6s?t=469

Arcanox's experience is worrying me about the dealer being unable to fix the backfire issue. I still haven't found a solid opening in my schedule during the day to bring my Volt in and dread wasting time if it doesn't get the backfire issue resolved.
 
#38 ·
That sounds closer to the cabin than the sound I hear, but it's similar and it happens at the same time...

Mine sounds much more hollow and distant as it's coming from the exhaust (or somewhere very close). Maybe tomorrow I'll take a drive in Hold mode and put a camera in my trunk to see if I can capture it...
 
#39 · (Edited)
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.
 
#40 ·
I use my ICE every time I drive to work (45 mile commute each way, can't charge at work) so it's definitely been broken in. It hasn't been as noticeable in the winter; it seems like it happens more when it's hot and the engine can get near 200 *F on the coolant gauge.
 
#41 ·
Arcanox, I was hoping I got lucky and the problem worked itself away due to ICE usage. Today, for the first time I heard the backfire again after depleting charge. It was warmer today (40F) so maybe it has to do with temps. However, seeing as you're in Chicago, you've probably got plenty of cold to simulate my backfire-free commutes of late. This is such a bizarre side affect. Not enough to make me regret my Volt, but had I known about this problem, I would've tested for it first before acceptance and signing the paperwork.
 
#42 ·
[cross posted from this thread for future searchers]

(some background, I tried changing from gas mixed with 10% ethanol to pure gas, the kind you find at marinas, to see if it changed the behavior of the after fires/bang sounds)

So I filled up my tank from 1.6 gas+ethanol (I forget the %, but I think 10% is safe to assume) to 8.9 of pure gas. Given similar ambients so far (50F morning commute on ICE, 60F-75F evenings on ICE) I think I'm getting more afterfires now. I used to only get a single bang, but now I occasionally get 2 in a row from a single acceleration. I do not think I let off accelerator then re-apply accelerator, just a single, smooth acceleration.

It's now annoying me. I prefer the single afterfire. Seems to me the fuel mixture is getting more rich? I thought modern ICE engines have various sensors that prevent oddities like knocking and misfires.
 
#43 ·
Our 2016 Volt had the engine/power train, update back in Dec. or Jan. 17. After it was done the engine ran smoother and mpg in gas engine mode noticeably improved. We purchased in July 2016. The mpg stats from Voltstats.net average for the July-Dec was about 43-44 mpg avg on gas. After the update, even though it was winter, mpg's improved to about 47-48 mpg average for Jan - June 2017. Last trip on the Volt gauge was nearly 50 mpg just on gas. (calculated was over 50 mpg)

I notice sometimes I don't know if the engine is running or not. I have to hit the flow button to check at times.
 
#44 ·
So my 2016 Volt (9/15 build date) just starting backfiring on startup as my engine racked up about 3000 miles on it.

Dealer said that a new bulletin just got released from GM... Details below... GM is working on a fix....

#PIP5518: Rattle Or Pop Noise During Gas Engine Start - (Sep 11, 2017)
Subject: Rattle Or Pop Noise During Gas Engine Start


________________________________________
Brand: Model: Model Year: VIN: Engine: Transmission:
from to from to
Chevrolet Volt 2016-2018 All All 1.5L L3A All


Involved Region or Country North America
Additional RPO/s: None
Condition Rattle Or Pop Noise During Gas Engine Start
Cause Under Investigation At This Time.
Correction
Some customers may have a concern of a rattle or pop noise during gas engine start.
This concern only occurs on low speed tip in type maneuvers.
It would normally be duplicated during stop go traffic type of situations where the engine starts in the 2000 rpm range.
This issue will not occur on zero vehicle speed starts or during high pedal input starts.
If no codes or other symptoms are present, do not attempt repairs at this time.
Advise the customer that GM Powertrain is aware of this concern and working on a resolution.
 
#48 ·
#PIP5518: Rattle Or Pop Noise During Gas Engine Start - (Sep 11, 2017)
Subject: Rattle Or Pop Noise During Gas Engine Start


________________________________________
Brand: Model: Model Year: VIN: Engine: Transmission:
from to from to
Chevrolet Volt 2016-2018 All All 1.5L L3A All


Involved Region or Country North America
Additional RPO/s: None
Condition Rattle Or Pop Noise During Gas Engine Start
Cause Under Investigation At This Time.
Correction
Some customers may have a concern of a rattle or pop noise during gas engine start.
This concern only occurs on low speed tip in type maneuvers.
It would normally be duplicated during stop go traffic type of situations where the engine starts in the 2000 rpm range.
This issue will not occur on zero vehicle speed starts or during high pedal input starts.
If no codes or other symptoms are present, do not attempt repairs at this time.
Advise the customer that GM Powertrain is aware of this concern and working on a resolution.
Awesome information!!! I'm really happy that GM has finally acknowledged this problem (just a year short of when I initially reported it!). That's interesting that they found it doesn't occur when the vehicle is stopped or when you floor it. I've never paid attention when I floor it because I usually only hear my tires spinning :)rolleyes:) and the only time the engine starts at zero-speed is during ERDTT.

I've noticed if the engine restarts very soon after shutdown (accelerate quickly, brake suddenly, accelerate again) it's much louder...this could be replicated at zero-speed by shifting from P to N back to P quickly with the hood open to see if GM's observations are correct all the time.
 
#45 ·
teksavy, that is odd that you started developing the misfires at ~3k ICE miles. I'm surprised you were actually keeping track of the silence of your Volt (keen ears). Thank you for replying back with the bulletin info. I'm really hoping GM finds the issue and can fix it without major changes to the Volt's performance.
 
#46 ·
We have over 5000 miles on our Volt without any issues YET. I do notice some slight engine roughness when climbing steep grades in hold mode...but it is very minor and infrequent. Whenever I do notice this it simply reminds me how great the car is when running on electric only......and makes me crave for more pure bev range. This thread about potential ICE related problems developing do not instill confidence. Fingers crossed that my Volt will remain reliable until I can move on to a pure BEV!
 
#47 ·
Just to continue the flow of updates, I'm at 25k miles on mine now (woah!) and still get this. It's much less often than before (probably because I'm driving less than 30 miles a week most weeks on gas now), but every trip that I have to use gas, I hear it at least once.

I do notice some slight engine roughness when climbing steep grades in hold mode...but it is very minor and infrequent.
You're probably noticing the clutches engaging and disengaging. It's a bit like an automatic shifting, but it does it at very odd times due to the way the transmission works. Going uphill will definitely make it more noticeable.
 
#49 ·
Just wanted to update this thread.

As of the date of this post, no new remedy has been released by GM. I asked my service advisor if the bulletin has been updated and he checked and the answer was 'no'.

Darn... Hopefully soon.

-Ed
 
#50 ·
I was just in to my dealer last week for this same issue as well as some other ones. I had to educate the tech about the sound, but unfortunately, he was unable to duplicate it. However, he said that he believed me, and showed me official paperwork which states "GM is currently validating a correction for this concern that will be available in the second quarter of 2018".

As I was leaving the dealership and turning into traffic, my car made the noise! I quickly returned to the dealer, and got him to take a ride with me. It took only about 3 minutes, and I was successful in getting him to hear the sound several times. He now knows what to listen for, and that I wasn't making it up!
 
#52 ·
he said that he believed me, and showed me official paperwork which states "GM is currently validating a correction for this concern that will be available in the second quarter of 2018".
Just wanted to resurrect this thread to see if anyone got this fixed since it was supposedly coming out "in the 2d quarter of 2018" (although half the time I think dealerships make this stuff up hoping we don't actually come back, or post their answers on forums).
 
#51 ·
fintonissimo, that's hopeful! Thank you for the update! Wish I had the patience to have kept my Volt now...
 
#53 ·
Picked up my ‘18 Premier 3 weeks ago. I had a ‘12 Volt which I traded in for a ‘15 Mercedes Electric Drive, which I’ll call my “3 year mistake”. The first time the gas engine kicked in, I heard this bang, and thought that maybe as a brand new engine, this was part of the break-in process. I’ve only used .10 gallon in 3 weeks so haven’t heard it since.

Coming back to the forum today, this thread caught my eye immediately. I’ll be using gas on a trip tomorrow, and will feel less concerned knowing that it’s a known issue and not just me. Seems like Chevy is dragging their feet with a fix
 
#56 ·
I think the only real way to exact change is to invoke Lemon Law, regardless if they say "they're working on it." I think their instructions to dealers even mention not to attempt to fix, probably to avoid a Lemon Law trigger.

Hopefully someone with more fortitude than I can stand up to GM and leverage the Lemon Law to trigger real pain for GM can get this issue fixed.
 
#57 ·
This fix is here! The PIP5518B has been morphed into a TSB 18-NA-174. I'm scheduled to have it done on Monday. Dealer confirmed it will be covered under the Emissions warranty.

I'll keep everyone posted on my outcome.

-Ed
 
#58 · (Edited)
Dang it's about time!!!! Scheduling this ASAP. Appreciate the update. Was almost ready to jump into a '19 if they had fixed it in that model. Now no excuse...

By the way, can't locate the updated TSB on revbase. Maybe it hasn't snaked its way to the third-party software systems yet. If you get a copy, would be curious what it says.
 
#61 ·
Has anyone with the backfiring problem ever tried using premium fuel? I understand the higher octane is designed to be harder to detonate. Might be worth a try.
 
#63 ·
Got the TSB 18-NA-174 (formerly PIP5518B) applied this morning and I'm happy to report that the backfiring in gone and as a bonus the engine startup seems smoother.

I'll update this post if anything changes.

Fully covered under the emissions warranty.

I noted (using my VXDiag Scan Tool) the following before and after software revisions:


Hybrid Powertrain Control Module:
From:
Software Module 1 Identifier 24279916
Software Module 2 Identifier 24284750
Software Module 3 Identifier 24284749
Software Module 4 Identifier 24284748

To:
Software Module 1 Identifier 24290760
Software Module 2 Identifier 24293637
Software Module 3 Identifier 24293636
Software Module 4 Identifier 24293635

Drive Motor Control Module 1
From:
Software Module 3 Identifier 24285143

To:
Software Module 3 Identifier 24294585


Drive Motor Control Module 2
From:
Software Module 3 Identifier 24285145

To:
Software Module 3 Identifier 24294586

 
#66 ·
Please let us know if you see an increase in mpg when operating just on the gas engine. We have a 2016 Volt Premier purchased in Oct. 2016 and I will check today with our Chevy dealer to see if this TSB was completed on our Volt. I know they did do an update for the chugging issue back about 1 1/2 years ago. I don't hear a backfire when the engine fires up, but it still does not run as smooth when in gas mode as I would like. However our mpg just on gas has been over 50 mpg with no complaints in that area....
 
#67 ·
Scheduled mine for this Friday. Hope the dealer knows about it and has the update. I quoted the TSB number in the service request. Haven’t seen any more info on what the TSB says so if anyone has that info it would be good to post it. Can’t imagine these backfires are good for the catalytic converters in the long run. Had a Saturn that had a misfire and it plugged the converter almost instantly.
 
#68 ·
Well taking my Volt in for this update did not go as planned.

I scheduled the appointment thru the onStar app and receive an email confirmation of the appt directly from the dealer (Roy Foss Woodbridge)

When I took the car in she said I didn’t have an appt and would have to leave it there all day. I showed her the email from Roy Foss and she could not explain why I don’t have an appt yet got the email confirmation

When she checked my VIN for updates and campaigns she showed nothing being required. Told her the TSB # and got nowhere with it.

Called GM EV advisor, she checked my car VIN and again nothing showed. They are referring it to a specialist to call me back.

My understanding is that this TSB applies to all G2 cars, and mine has the backfire issue from day 1

Anybody have more info on this TSB and applicability to Volt years?
 
#70 ·
Well taking my Volt in for this update did not go as planned.
What a crapshow. Regrettably, seems all-too-familiar with the experiences of many with various service departments/customer service. SOMEONE knows that this actually applies to your car--somewhere. But who's going the extra mile to help you out for a known issue?

Keep us updated. Hope it ends well.
 
#69 ·
I'm taking my Volt in next Friday for this issue, and despite already being in the system with a TAC Case, they said they have to duplicate the problem yet again before they can fix it. I'm hoping for the best, but this is already not looking good. Now they'll have to drive around for 20 miles before doing anything.
 
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