Is this normal?
Thread Starter
Burning Brakes
Joined: Jan 2015
Posts: 789
Likes: 212
From: Katy Texas
Is this normal?
So far, I'm digging the Z06. Wowzers.
Quick question tho. Does anyone else have any rpm rev increase off throttle?
For example. If I'm just cruising at low speeds. If I blip the throttle the car obviously reacts and accelerates, but once I'm off throttle, it still seems to rev out for a second and car seems to lunge forward even off throttle. It's just a quick second blip of increases rpms when I'm off throttle. Kind of strange.
So, it's a quick on and off throttle, but the rpms' still want to rev up once I'm off throttle. So, I'm finding myself having to tap the brake a little bit. Most cars I've ever own, once you are off throttle the revs obviously decrease as soon as you are off throttle. It doesn't happen all of the time, so I'm just wondering if I'm in between some kind of rev match or something. Who knows.
It might be a stupid question, but as I get to know the car, I'm noticing things.
Quick question tho. Does anyone else have any rpm rev increase off throttle?
For example. If I'm just cruising at low speeds. If I blip the throttle the car obviously reacts and accelerates, but once I'm off throttle, it still seems to rev out for a second and car seems to lunge forward even off throttle. It's just a quick second blip of increases rpms when I'm off throttle. Kind of strange.
So, it's a quick on and off throttle, but the rpms' still want to rev up once I'm off throttle. So, I'm finding myself having to tap the brake a little bit. Most cars I've ever own, once you are off throttle the revs obviously decrease as soon as you are off throttle. It doesn't happen all of the time, so I'm just wondering if I'm in between some kind of rev match or something. Who knows.
It might be a stupid question, but as I get to know the car, I'm noticing things.
Last edited by txapezl1; Feb 17, 2016 at 03:49 PM.
Melting Slicks
Joined: Oct 2010
Posts: 2,162
Likes: 338
From: Fair Oaks, California
2017 C7 of the Year Finalist
So far, I'm digging the Z06. Wowzers.
Quick question tho. Does anyone else have any rpm rev increase off throttle?
For example. If I'm just cruising at low speeds. If I blip the throttle the car obviously reacts and accelerates, but once I'm off throttle, it still seems to rev out for a second and car seems to lunge forward even off throttle. It's just a quick second blip of increases rpms when I'm off throttle. Kind of strange.
So, it's a quick on and off throttle, but the rpms' still want to rev up once I'm off throttle. So, I'm finding myself having to tap the brake a little bit. Most cars I've ever own, once you are off throttle the revs obviously decrease as soon as you are off throttle. It doesn't happen all of the time, so I'm just wondering if I'm in between some kind of rev match or something. Who knows.
It might be a stupid question, but as I get to know the car, I'm noticing things.
https://www.youtube.com/watch?v=_aZu...IwHoYopKB_b14A
Quick question tho. Does anyone else have any rpm rev increase off throttle?
For example. If I'm just cruising at low speeds. If I blip the throttle the car obviously reacts and accelerates, but once I'm off throttle, it still seems to rev out for a second and car seems to lunge forward even off throttle. It's just a quick second blip of increases rpms when I'm off throttle. Kind of strange.
So, it's a quick on and off throttle, but the rpms' still want to rev up once I'm off throttle. So, I'm finding myself having to tap the brake a little bit. Most cars I've ever own, once you are off throttle the revs obviously decrease as soon as you are off throttle. It doesn't happen all of the time, so I'm just wondering if I'm in between some kind of rev match or something. Who knows.
It might be a stupid question, but as I get to know the car, I'm noticing things.
https://www.youtube.com/watch?v=_aZu...IwHoYopKB_b14A
Thread Starter
Burning Brakes
Joined: Jan 2015
Posts: 789
Likes: 212
From: Katy Texas
Instructor
Joined: Mar 2006
Posts: 246
Likes: 33
From: Mission Viejo, Ca
If you are in Sport or Track mode the car is trying to keep you in that power band because it thinks you are on a track. If you are in Touring mode and it is happening then it is not normal.
Drifting
Joined: Apr 2008
Posts: 1,356
Likes: 105
From: Mesa AZ
Last edited by ktoonsez; Feb 17, 2016 at 04:37 PM.
Racer
Joined: Apr 2015
Posts: 429
Likes: 44
From: Las Vegas Nevada
Is it an A8? You might have blipped it enough that it goes into performance mode. If it just so happens that if it goes into performance mode when you are ready to slow down, it does feel like and actually is a lunge.
Anyhow that has been my experience.
Anyhow that has been my experience.
Safety Car
Joined: Aug 2005
Posts: 3,968
Likes: 867
From: Tulsa Oklahoma
Mine did it when I first got the car but after putting some miles on the car it fixed itself and stopped surging.
https://www.corvetteforum.com/forums...yone-else.html
https://www.corvetteforum.com/forums...yone-else.html
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Burning Brakes
Joined: May 2002
Posts: 1,010
Likes: 13
i have encountered this many times since september, and every time i think, at minimum this is unsettling, and even feels a bit unsafe. Every time i am surprised the engineers would let that happen. I will keep track of what mode it happens in. It doesnt happen quite so much and severe that it makes me dislike the car. It is manageable at this level. If it were twice as bad or more than twice as bad, it would probably start to affect my enjoyment of the car. Its probably the one thing that makes me miss my c6z. The control of the power with that car was very precise in comparison to this one. Probably due to the a8, which is expected, but this surging thing took me by surprise. I still wouldnt choose the stick as a daily driver though, did that for 10 years with the c6z, and its just too tedious. For a track only car i would choose a stick though for the much better power control.
Last edited by TripleBlack99; Feb 17, 2016 at 05:52 PM.
Safety Car
Joined: Sep 2011
Posts: 3,913
Likes: 395
From: Cary NC
If you have a M7 I don't think it is normal at all. Never experienced that phenomenon. Sounds more like something that might happen with an automatic transmission. What transmission do you have?
Last edited by CaryBob; Feb 17, 2016 at 06:01 PM.
Thread Starter
Burning Brakes
Joined: Jan 2015
Posts: 789
Likes: 212
From: Katy Texas
I have an A8.
Last edited by txapezl1; Feb 17, 2016 at 07:14 PM.
Thread Starter
Burning Brakes
Joined: Jan 2015
Posts: 789
Likes: 212
From: Katy Texas
Yea, that's another thing. The performance mode in Auto mode. I like it cus it revs down gears fast with almost no lag, but then it can't predict a false rev either and keeps rpm's up even if I'm not really racing. I think you can hit the paddle and it overrides it. Anyhow, I'm learning the car as I drive it more.
Safety Car
Joined: Nov 2012
Posts: 4,737
Likes: 551
From: North California
I didn't notice it at first even when others reported it. But having driven the car for 17,000 miles now it is definitely there.
I'm 99% sure it's just the inertia of a belt driven supercharger. It doesn't happen off boost which leads many to believe it's not happening with their car. This was certainly the case for me when I was breaking-in the car.
There may or may not be a solution for this behavior. I've read an article where the Dodge team have a bypass specifically to eliminate this behavior.
Anyone have a Hellcat and a Z and is willing to let off the gas at full boost and observe the throttle input decay rate?
"From the standpoint of driveability and durability, Hellcat has two other interesting features. An electronically controlled internal bypass valve located between the inlet side and the discharge side of the compressor allows air to move directly into the intake ports without being compressed. Under low load and off-throttle conditions, it lowers parasitic drag on the engine and reduces wear on the compressor. The other feature is a decoupler—a one-way mechanical diode—inside the supercharger pulley, which only allows torque to be transmitted in one direction. The compressor's rotors are then allowed to freewheel when engine speed suddenly drops, during shifts for instance, thus saving unnecessary wear on the compressor's geardrive and preventing problematic drivebelt dynamics."
http://www.hotrod.com/features/1502-...-hellcat-hemi/
See? The Z has the bypass but I don't think it has a decoupler. The decoupler sounds like it would eliminate the inertia of the rotors when the rpms drop when you take your foot off the gas.
I'm 99% sure it's just the inertia of a belt driven supercharger. It doesn't happen off boost which leads many to believe it's not happening with their car. This was certainly the case for me when I was breaking-in the car.
There may or may not be a solution for this behavior. I've read an article where the Dodge team have a bypass specifically to eliminate this behavior.
Anyone have a Hellcat and a Z and is willing to let off the gas at full boost and observe the throttle input decay rate?
"From the standpoint of driveability and durability, Hellcat has two other interesting features. An electronically controlled internal bypass valve located between the inlet side and the discharge side of the compressor allows air to move directly into the intake ports without being compressed. Under low load and off-throttle conditions, it lowers parasitic drag on the engine and reduces wear on the compressor. The other feature is a decoupler—a one-way mechanical diode—inside the supercharger pulley, which only allows torque to be transmitted in one direction. The compressor's rotors are then allowed to freewheel when engine speed suddenly drops, during shifts for instance, thus saving unnecessary wear on the compressor's geardrive and preventing problematic drivebelt dynamics."
http://www.hotrod.com/features/1502-...-hellcat-hemi/
See? The Z has the bypass but I don't think it has a decoupler. The decoupler sounds like it would eliminate the inertia of the rotors when the rpms drop when you take your foot off the gas.
Last edited by SBC_and_a_stick; Feb 17, 2016 at 07:31 PM.
Safety Car
Joined: Nov 2012
Posts: 4,737
Likes: 551
From: North California
Le Mans Master
Joined: Jun 2008
Posts: 8,255
Likes: 411
From: Mt. Sinai NY
So far, I'm digging the Z06. Wowzers.
Quick question tho. Does anyone else have any rpm rev increase off throttle?
For example. If I'm just cruising at low speeds. If I blip the throttle the car obviously reacts and accelerates, but once I'm off throttle, it still seems to rev out for a second and car seems to lunge forward even off throttle. It's just a quick second blip of increases rpms when I'm off throttle. Kind of strange.
So, it's a quick on and off throttle, but the rpms' still want to rev up once I'm off throttle. So, I'm finding myself having to tap the brake a little bit. Most cars I've ever own, once you are off throttle the revs obviously decrease as soon as you are off throttle. It doesn't happen all of the time, so I'm just wondering if I'm in between some kind of rev match or something. Who knows.
It might be a stupid question, but as I get to know the car, I'm noticing things.
https://www.youtube.com/watch?v=_aZu...IwHoYopKB_b14A
Quick question tho. Does anyone else have any rpm rev increase off throttle?
For example. If I'm just cruising at low speeds. If I blip the throttle the car obviously reacts and accelerates, but once I'm off throttle, it still seems to rev out for a second and car seems to lunge forward even off throttle. It's just a quick second blip of increases rpms when I'm off throttle. Kind of strange.
So, it's a quick on and off throttle, but the rpms' still want to rev up once I'm off throttle. So, I'm finding myself having to tap the brake a little bit. Most cars I've ever own, once you are off throttle the revs obviously decrease as soon as you are off throttle. It doesn't happen all of the time, so I'm just wondering if I'm in between some kind of rev match or something. Who knows.
It might be a stupid question, but as I get to know the car, I'm noticing things.
https://www.youtube.com/watch?v=_aZu...IwHoYopKB_b14A
Clif
Racer
Joined: Dec 2009
Posts: 356
Likes: 23
From: Augusta Georgia
I have experienced it with other rides
My E55 Mercedes and my Harley Truck, both supercharged and automatic transmission vehicles seemed to have power surges after you had just rolled out of the throttle, particularly coming out of a burnout.
Melting Slicks
Joined: Oct 2007
Posts: 2,398
Likes: 858
It comes from the way the torque delivery is programmed in the PCM.
There will always be a lag between requested torque, commanded torque and lastly delivered torque. This delay is probably only a couple of thousandths of a second maybe less but it is there.
I believe the surge we feel happens after you close the throttle completely (0 torque requested and 0 torque commanded) and when the PCM commands idle torque (around 5-7%).
If you are quick enough to get completely off the throttle and then barley back on it (roughly 8-10% throttle opening) you will notice the surge never comes in. Release completely and stay off of the accelerator and the surge is always there. (at least in the M7 Stingray and Z06 anyway.)
Last edited by dar02081961; Feb 17, 2016 at 08:49 PM.
Safety Car
Joined: Nov 2012
Posts: 4,737
Likes: 551
From: North California
My Stingray did it as well as my Z06. pretty sure it isn't boost related though possibly worse on the Z06.
It comes from the way the torque delivery is programmed in the PCM.
There will always be a lag between requested torque, commanded torque and lastly delivered torque. This delay is probably only a couple of thousandths of a second maybe less but it is there.
I believe the surge we feel happens after you close the throttle completely (0 torque requested and 0 torque commanded) and when the PCM commands idle torque (around 5-7%).
If you are quick enough to get completely off the throttle and then barley back on it (roughly 8-10% throttle opening) you will notice the surge never comes in. Release completely and stay off of the accelerator and the surge is always there. (at least in the M7 Stingray and Z06 anyway.)
It comes from the way the torque delivery is programmed in the PCM.
There will always be a lag between requested torque, commanded torque and lastly delivered torque. This delay is probably only a couple of thousandths of a second maybe less but it is there.
I believe the surge we feel happens after you close the throttle completely (0 torque requested and 0 torque commanded) and when the PCM commands idle torque (around 5-7%).
If you are quick enough to get completely off the throttle and then barley back on it (roughly 8-10% throttle opening) you will notice the surge never comes in. Release completely and stay off of the accelerator and the surge is always there. (at least in the M7 Stingray and Z06 anyway.)
