Engine Pop
Thread Starter
Heel & Toe
Joined: Sep 2020
Posts: 17
Likes: 2
From: Daytona Beach FL
Engine Pop
I have a 2018 C7 w/Z51 package, 12K miles. I’ve made a few small mods - high end air filter, pulled the NPP breaker, and added AFS override. This issue has happened several times so I decided to ask why? When I put my foot in the gas and run through the paddle gears (automatic) it pops once around 4th gear - not at the shift point but when I’m hammering down the gas pedal. If it’s nothing I’ll be happy to ignore it - just don’t want it to get worse. TIA.
Team Owner
Joined: Sep 2000
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From: Far NW 'burbs of Chicago
St. Jude Donor '13
Under full throttle, a "Pop" as the transmission upshifts is normal and sounds nice.
A Pop at any other time is probably not good, at least I've never experienced it and have never heard of it.
A Pop at any other time is probably not good, at least I've never experienced it and have never heard of it.
Drifting
Joined: Sep 2017
Posts: 1,464
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From: Miami
C7 of Year Finalist (performance mods) 2019
Could be a number of things. Try to post a video or audio, if possible.
Perhaps it's just your exhaust popping. Try closing the valves and see if it continues.
Perhaps it's just your exhaust popping. Try closing the valves and see if it continues.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
A pop during shifting under full throttle is normal. The manual talks about it. The computer cuts the fuel for 100ms to allow the transmission to shift faster. I'm not sure why they cut the fuel but that's what the manual says. It happens under WOT on my car. A pop at any other time would be a concern.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
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From: Santa Maria, CA
Le Mans Master
Joined: Dec 2000
Posts: 5,348
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The pops are the result of fuel added during overrun. Overrun is when the driver closes the throttle, but the engine is still spinning while not doing any work (the drivetrain is turning the engine). The ECU keeps some fuel running to the injectors even though the driver has shut the throttle. This decreases engine braking. The added fuel helps cool the engine and control temperatures. It also makes a sudden throttle on smoother. And it makes race cars shoot flames out of the exhaust on quick throttle off. 
Manufactures tweak these value for high performance cars to add a bit of deceleration popping because most enthusiasts enjoy the sound.
My stock Z06 pops the most on snap throttle off in second or third gear at around 3,000 RPM. I find it amusing.
Manufactures tweak these value for high performance cars to add a bit of deceleration popping because most enthusiasts enjoy the sound.
My stock Z06 pops the most on snap throttle off in second or third gear at around 3,000 RPM. I find it amusing.
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Instructor
Joined: May 2008
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From: CA
Though it did sound kind of cool since I never owned a car that did that before. Kind of a raw, beastly characteristic.
Last edited by spoolin03; Jul 11, 2021 at 03:26 PM.
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Mine will pop when accelerating under heavy throttle when the upshifts occur. Just figured it was normal.
Melting Slicks
Joined: Mar 2008
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From: Santa Maria, CA
Le Mans Master
Joined: Dec 2000
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Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
I read it when I bought my 2015 six years ago. I now have a 2017 and I don't have the older manual. I see it is not in the 2017 manual. It was provided as information and stated that under wide open throttle the ECM cuts the fuel for 100ms at the shift. It was either to improve the shift of lessen the impact to the transmission. My 2015 did it and so does my 2017. It may have to do with the driving mode. I don't know, I always drive in Sport. As a note, the old manual discussed tire crabbing as a normal condition too. That's no longer in the manual either. Maybe just too much information for some people.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
OK. So what's your point? The subject appears on other corvette forums and on other threads in this forum. You yourself said on another thread that it was normal.
Le Mans Master
Joined: Dec 2000
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I am hoping to track down additional actual, verifiable information. You claimed further information is in the Owner's Manual. Unable to find it, I asked you for the language in the manual. Unfortunately it turns out your claim is untrue; it is not in the manuals.
If you run across real, supplemental information, please post it.
If you run across real, supplemental information, please post it.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
I am hoping to track down additional actual, verifiable information. You claimed further information is in the Owner's Manual. Unable to find it, I asked you for the language in the manual. Unfortunately it turns out your claim is untrue; it is not in the manuals.
If you run across real, supplemental information, please post it.
If you run across real, supplemental information, please post it.
Team Owner
Joined: Sep 2000
Posts: 25,029
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From: Far NW 'burbs of Chicago
St. Jude Donor '13
Regardless of whether the Pop information is or isn't in print, my totally stock 2017 Z51 A8 has been doing it since I got past the 1500 mile track break in. Now at 40k miles and still doing it. I've been standing on the sidelines and listened to lots of other C8's doing the Pop as the A8 shifts under full throttle.
Le Mans Master
Joined: Dec 2000
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As it turns out, you were wrong. The manual says no such thing.
I am sorry this upsets you.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
I need a citation to authority to justify my opinion? Where's your citation for the BS explanation you gave? My opinion is backed up with the experience of many, many other forum members in numerous threads over 7 years. I think your opinion came out of your ***. Now are you upset?