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Discussion Starter #1
I've got a C7, Z51, exhaust , and it's an automatic. When I'm accelerating hard, just before a shift, there's a pop that is very noticeable. I've tried to go through the gears manually and the same pop just as I'm going into the next gear. I'd like to hear from anyone that has the same sounds I do, or a mechanic that could explain it.
 

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I had the chance to hit it hard up a freeway ramp this morning and I too heard a pop when it shifted from 2nd to 3rd. Glad to hear it is "Normal".
 

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I had the chance to hit it hard up a freeway ramp this morning and I too heard a pop when it shifted from 2nd to 3rd. Glad to hear it is "Normal".
Interesting I hear it is normal? My neighbor has a coupe auto and his does not pop? is this a z51 thing only or both models? If both why does his not pop?
 

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Interesting I hear it is normal? My neighbor has a coupe auto and his does not pop? is this a z51 thing only or both models? If both why does his not pop?
Dependent on how hard you are stomping on the gas not related to base vs Z51.
 

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Dependent on how hard you are stomping on the gas not related to base vs Z51.
Yes my neighbor stomped on the gas, he likes to race with other cars on the streets and no pops from his c7?
 

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Yes my neighbor stomped on the gas, he likes to race with other cars on the streets and no pops from his c7?
Does he have the NPP and is it set to "off" or non-linked to drive mode? RedHot pops pleasingly :D
 

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Does he have the NPP and is it set to "off" or non-linked to drive mode? RedHot pops pleasingly :D
he does not have npp, that may be the clue to being normal?
 

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Need a tech here, it has to do with the gas loading up prior to a hard shift and then igniting, I'm not a tech so this may be wrong but I think it does it on all a6's, not exhaust dependent......mark should know?

See comment from zl1 here, I've read it more than once in a couple places:

Pop and max RPM shifts - Corvette Forum
I would like to have this verified by someone like the Ron Fellows driving class that i plan to attend sometime towards the end of this year or in Jan 2015? If there are any students going in the near future maybe they can verify this and then post their finding?
 

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I would like to have this verified by someone like the Ron Fellows driving class that i plan to attend sometime towards the end of this year or in Jan 2015? If there are any students going in the near future maybe they can verify this and then post their finding?
I think you place a lot more faith in the knowledge of the Ron Fellows instructors than is warranted as this is the 2nd or 3rd time you have mentioned this. If you believe this is a problem your solution lies with your dealer and GM Customer Service.

On this issue it's programmed in the fuel management as it momentarily kills ignition while still operating the fuel injectors. This causes a small amount of unburnt fuel to pass through the cylinder and light off when it hits the hot exhaust. It can be tuned out with the ECM but it's been reported it was left in to mimic the sequential shifter on the race car.

Bottom line, it's normal but it doesn't always happen.


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Get the manual transmission and select the mode that deactivates the cylinder deactivation. If you believe that you paid for all 8 cylinders, why want 4 of them to shut off in a high performance car? I don't get it!!


Jud

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Get the manual transmission and select the mode that deactivates the cylinder deactivation. If you believe that you paid for all 8 cylinders, why want 4 of them to shut off in a high performance car? I don't get it!!


Jud


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You're right, you don't get it....on a full on A6 acceleration, AFM is no where involved...
 

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Get the manual transmission and select the mode that deactivates the cylinder deactivation. If you believe that you paid for all 8 cylinders, why want 4 of them to shut off in a high performance car? I don't get it!!


Jud

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We have AFM so we can have a 460hp sportscar. Without the MPG these features provide GM would not produce the Corvette in volume due to CAFE regulations but we are drifting off topic.


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they all pop, it's due to the oxygen being injected into the exhaust system from the engine management system cutting off fuel delivery for a split second. kind of an annoyance if you ask me, but some people like it.
 

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they all pop, it's due to the oxygen being injected into the exhaust system from the engine management system cutting off fuel delivery for a split second. kind of an annoyance if you ask me, but some people like it.
I like it.


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Get the manual transmission and select the mode that deactivates the cylinder deactivation. If you believe that you paid for all 8 cylinders, why want 4 of them to shut off in a high performance car? I don't get it!!

Jud

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Although I own spoons and shovels and spades, I only eat my cereal out of a spoon.

I also do not use a sledgehammer to mount a picture on the wall.

It is nice to have all the fun tools, but it doesn't make sense to use something inefficient when it is not needed.
 
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Discussion Starter #19
Wow, I just got home so I thought I would see if anyone replied to my question of a pop while shifting under hard acceleration. 16 fellow Vette owners chimed in. This is so cool to have this forum to get input on any issue. Thanks gentlemen...
 
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