Lack of power on highway at WOT
07-16-2019, 01:30 PM
#1
Heel & Toe
Thread Starter
Lack of power on highway at WOT
Hi all, I did a search for this possible issue I'm having but didn't see any threads that appear to be on point. I have a 2015 Z06, Z07 package car that has only 5,000 miles on the odometer and is still pretty new to me. There's an issue that I seem to be having, but I can't decide if it's really a problem or if I'm just not used to the car. Here it is:
When I'm on the highway in Touring mode, but in manual shifting mode (i.e., no cylinder deactivation), and cruising in say 5th-6th gear at around 2500 rpm and I pin the throttle, there is a very underwhelming response from the engine. The exhaust valves open and the car makes a lot of noise but it feels like there isn't much additional power/torque being provided from the engine. This occurs, for example, when I'm following another car and go to pass it. In that situation, the car barely gains on the car I'm attempting to pass. While I'd expect this from a car with a peaky torque curve that you need to wring out to get into the meat of the torque band, I wouldn't expect it from a car with over 500 lb-ft of torque available at that level of rpm.
Is this normal? Are 5th-6th gears relatively long gears? While I can certainly downshift to pass in such situations, it feels like I shouldn't have to with as much power/torque the car has. Obviously, if there is something wrong with the car, I would like to address it. Any insights would be appreciated. Thanks!
Edit: I have also noticed this in Sport mode so I don't believe that it's a problem with driving modes.
When I'm on the highway in Touring mode, but in manual shifting mode (i.e., no cylinder deactivation), and cruising in say 5th-6th gear at around 2500 rpm and I pin the throttle, there is a very underwhelming response from the engine. The exhaust valves open and the car makes a lot of noise but it feels like there isn't much additional power/torque being provided from the engine. This occurs, for example, when I'm following another car and go to pass it. In that situation, the car barely gains on the car I'm attempting to pass. While I'd expect this from a car with a peaky torque curve that you need to wring out to get into the meat of the torque band, I wouldn't expect it from a car with over 500 lb-ft of torque available at that level of rpm.
Is this normal? Are 5th-6th gears relatively long gears? While I can certainly downshift to pass in such situations, it feels like I shouldn't have to with as much power/torque the car has. Obviously, if there is something wrong with the car, I would like to address it. Any insights would be appreciated. Thanks!
Edit: I have also noticed this in Sport mode so I don't believe that it's a problem with driving modes.
Last edited by RFR Z06; 07-16-2019 at 01:45 PM.
07-16-2019, 02:16 PM
#2
If you're in manual mode and you want to pass someone, why aren't you downshifting? The engine does make a lot of low end torque but if your goal is to pass someone aggressively, or to put "bus lengths", then you're in the wrong gear, downshift.
Or leave it in D, and let the computer downshift for you. The paddles are useless on these cars. But then again the auto isn't exactly great either.
Or leave it in D, and let the computer downshift for you. The paddles are useless on these cars. But then again the auto isn't exactly great either.
07-16-2019, 02:28 PM
#3
Sounds like you may have a problem. It could be several things, such as timing being pulled, etc. If you are cruising at 70 in 5th and pin it you should be in triple digits in a matter of seconds. 7th gear can be sluggish but 5th is usually what I use to pass on the highway.Others may understand the A8 better since mine is an M7. Hope you get it straightened out!
07-16-2019, 03:43 PM
#5
07-16-2019, 04:51 PM
#6
Hi all, I did a search for this possible issue I'm having but didn't see any threads that appear to be on point. I have a 2015 Z06, Z07 package car that has only 5,000 miles on the odometer and is still pretty new to me. There's an issue that I seem to be having, but I can't decide if it's really a problem or if I'm just not used to the car. Here it is:
When I'm on the highway in Touring mode, but in manual shifting mode (i.e., no cylinder deactivation), and cruising in say 5th-6th gear at around 2500 rpm and I pin the throttle, there is a very underwhelming response from the engine. The exhaust valves open and the car makes a lot of noise but it feels like there isn't much additional power/torque being provided from the engine. This occurs, for example, when I'm following another car and go to pass it. In that situation, the car barely gains on the car I'm attempting to pass. While I'd expect this from a car with a peaky torque curve that you need to wring out to get into the meat of the torque band, I wouldn't expect it from a car with over 500 lb-ft of torque available at that level of rpm.
Is this normal? Are 5th-6th gears relatively long gears? While I can certainly downshift to pass in such situations, it feels like I shouldn't have to with as much power/torque the car has. Obviously, if there is something wrong with the car, I would like to address it. Any insights would be appreciated. Thanks!
Edit: I have also noticed this in Sport mode so I don't believe that it's a problem with driving modes.
When I'm on the highway in Touring mode, but in manual shifting mode (i.e., no cylinder deactivation), and cruising in say 5th-6th gear at around 2500 rpm and I pin the throttle, there is a very underwhelming response from the engine. The exhaust valves open and the car makes a lot of noise but it feels like there isn't much additional power/torque being provided from the engine. This occurs, for example, when I'm following another car and go to pass it. In that situation, the car barely gains on the car I'm attempting to pass. While I'd expect this from a car with a peaky torque curve that you need to wring out to get into the meat of the torque band, I wouldn't expect it from a car with over 500 lb-ft of torque available at that level of rpm.
Is this normal? Are 5th-6th gears relatively long gears? While I can certainly downshift to pass in such situations, it feels like I shouldn't have to with as much power/torque the car has. Obviously, if there is something wrong with the car, I would like to address it. Any insights would be appreciated. Thanks!
Edit: I have also noticed this in Sport mode so I don't believe that it's a problem with driving modes.
The torque capability of the transmission is limited at lower rpm for the high performance car versions of the transmission due to excessive heat produced in this envelope (as well as a few other factors). The truck versions are slightly different internally and have larger coolers and more cooling capacity (they trade high rpm flexibility). This is why some passenger cars have the option of a "towing package". Operating under heavy torque for long periods at low RPM is a killer for an automatic transmission.
The M7 is limited as well for the overdrive gears in the lower rpm areas of the torque curve but not as much.
Without the slippage inherent in the automatic transmission heat isn't as much a concern in the M7 but there are other physical component limits as well.
Last edited by dar02081961; 07-16-2019 at 04:54 PM.
07-16-2019, 05:29 PM
#7
Tech Contributor
Member Since: Oct 1999
Location: Charlotte, NC (formerly Endicott, NY)
Posts: 40,094
Received 8,928 Likes
on
5,333 Posts
OP: If your description matches what the car is doing then you have some sort of problem.
From what I can judge 4th and 5th gears in the A8 are approximately the same final gear ratios as 3rd and 4th (1:1) gear in the M7 once you take the differential gearing into account. Any Z06 M7 will accelerate very quickly from 2500 rpm in 4th gear. Admittedly, the A8 in 5th has a few tenths less gear ratio than the M7 in 4th but that isn't enough to offset the huge amount of torque that is applied when you floor the throttle. You go from whatever torque is being produced at part throttle to max torque at that rpm which is just short of 600 lb ft. The A8 isn't into an overdrive gear until it is in 7th. Sixth is 1:1.
With my M7 the torque delivery is strong enough that when I was on track last year running Pirelli Slicks (that were up to temperature) that I broke the rear tires loose and spun the car off course when going wide open in 4th gear at ~ 90 mph. Not shifting into 4th but just going from part throttle to wide open. The engine rpms were above the max torque level rpm at wide open throttle so torque levels were falling off as engine speed increased but they were about the same level as 2500 rpm would get you although torque would increase from 2500 all the way to 3600 rpm.
Bill
From what I can judge 4th and 5th gears in the A8 are approximately the same final gear ratios as 3rd and 4th (1:1) gear in the M7 once you take the differential gearing into account. Any Z06 M7 will accelerate very quickly from 2500 rpm in 4th gear. Admittedly, the A8 in 5th has a few tenths less gear ratio than the M7 in 4th but that isn't enough to offset the huge amount of torque that is applied when you floor the throttle. You go from whatever torque is being produced at part throttle to max torque at that rpm which is just short of 600 lb ft. The A8 isn't into an overdrive gear until it is in 7th. Sixth is 1:1.
With my M7 the torque delivery is strong enough that when I was on track last year running Pirelli Slicks (that were up to temperature) that I broke the rear tires loose and spun the car off course when going wide open in 4th gear at ~ 90 mph. Not shifting into 4th but just going from part throttle to wide open. The engine rpms were above the max torque level rpm at wide open throttle so torque levels were falling off as engine speed increased but they were about the same level as 2500 rpm would get you although torque would increase from 2500 all the way to 3600 rpm.
Bill
The following 2 users liked this post by Bill Dearborn:
Jbugg (04-05-2020),
LagunaSecaZ06 (07-23-2019)
07-17-2019, 11:22 AM
#8
Yesterday my 2019 Z06 Vert had its 500 mile oil change. Today I took it for a ride. I have the A8 and was cruising at about 60-65mph. Trans was in Auto and the car was in Touring Mode. I put the gas pedal almost to the floor, it down shifted into 5th and took off like a rocket. I am running the Range AFM Disabler so no V4 mode.
Last edited by rjw1678; 07-17-2019 at 11:25 AM.
07-17-2019, 11:28 AM
#9
Heel & Toe
Thread Starter
Thanks Bill. I think it's a problem too. The experience reminds me of my mom's old Oldsmobile Cutlass back in the 80s. If you were driving uphill, you could floor it and the primary result was more noise but not much acceleration. I hate to sound old fashioned, but I'd much rather have a throttle cable that an electronic transmitter. Less likely to fail and at least then you can actually see what's happening and would know when there's a problem.
To those who said "downshift," I already covered that in my original post. Bottom line: If there's a problem with the car, I want to fix it, not work around it. I suspect you would too.
To those who said "downshift," I already covered that in my original post. Bottom line: If there's a problem with the car, I want to fix it, not work around it. I suspect you would too.
07-17-2019, 12:45 PM
#10
Safety Car
Hi all, I did a search for this possible issue I'm having but didn't see any threads that appear to be on point. I have a 2015 Z06, Z07 package car that has only 5,000 miles on the odometer and is still pretty new to me. There's an issue that I seem to be having, but I can't decide if it's really a problem or if I'm just not used to the car. Here it is:
When I'm on the highway in Touring mode, but in manual shifting mode (i.e., no cylinder deactivation), and cruising in say 5th-6th gear at around 2500 rpm and I pin the throttle, there is a very underwhelming response from the engine. The exhaust valves open and the car makes a lot of noise but it feels like there isn't much additional power/torque being provided from the engine. This occurs, for example, when I'm following another car and go to pass it. In that situation, the car barely gains on the car I'm attempting to pass. While I'd expect this from a car with a peaky torque curve that you need to wring out to get into the meat of the torque band, I wouldn't expect it from a car with over 500 lb-ft of torque available at that level of rpm.
Is this normal? Are 5th-6th gears relatively long gears? While I can certainly downshift to pass in such situations, it feels like I shouldn't have to with as much power/torque the car has. Obviously, if there is something wrong with the car, I would like to address it. Any insights would be appreciated. Thanks!
Edit: I have also noticed this in Sport mode so I don't believe that it's a problem with driving modes.
When I'm on the highway in Touring mode, but in manual shifting mode (i.e., no cylinder deactivation), and cruising in say 5th-6th gear at around 2500 rpm and I pin the throttle, there is a very underwhelming response from the engine. The exhaust valves open and the car makes a lot of noise but it feels like there isn't much additional power/torque being provided from the engine. This occurs, for example, when I'm following another car and go to pass it. In that situation, the car barely gains on the car I'm attempting to pass. While I'd expect this from a car with a peaky torque curve that you need to wring out to get into the meat of the torque band, I wouldn't expect it from a car with over 500 lb-ft of torque available at that level of rpm.
Is this normal? Are 5th-6th gears relatively long gears? While I can certainly downshift to pass in such situations, it feels like I shouldn't have to with as much power/torque the car has. Obviously, if there is something wrong with the car, I would like to address it. Any insights would be appreciated. Thanks!
Edit: I have also noticed this in Sport mode so I don't believe that it's a problem with driving modes.
The following users liked this post:
khoeysr (08-27-2019)
Love it! Best description I have ever heard! 
07-17-2019, 07:55 PM
#12
I agree...I noticed a similar reaction in D cruising on the interstate on my pickup day last week...I decided to make a "move" and pressed the go pedal and it seemed like I was in slow motion, not much happening so I let off to decide what just happened...tried it again a few minutes later but this time floored it and the A8 started downshifting like crazy and went how I would expect 650 HP to react. Again, not to keep repeating myself but the OEM Z06 are fast cars but nothing like my old 997 TT with 765+ H.P....when the turbos kicked in at 3,500 rpm you were leaving the area.
The following users liked this post:
Z0HS1CK (07-17-2019)
07-17-2019, 08:49 PM
#13
I agree...I noticed a similar reaction in D cruising on the interstate on my pickup day last week...I decided to make a "move" and pressed the go pedal and it seemed like I was in slow motion, not much happening so I let off to decide what just happened...tried it again a few minutes later but this time floored it and the A8 started downshifting like crazy and went how I would expect 650 HP to react. Again, not to keep repeating myself but the OEM Z06 are fast cars but nothing like my old 997 TT with 765+ H.P....when the turbos kicked in at 3,500 rpm you were leaving the area.
Either or, it's a shame GM put such a flawed auto in these cars. I can only imagine how much more amazing it would be if they stuffed the ZF 8 speed that's used in the hellcats and other cars like bentley etc.
But dude your porsche is a totally different animal compared to our cars. Both cars are insanely fast but put the power down completely different.
The Z is more like metallica and porsche is more like mozart. Both amazing but mozart (porsche) is more refined and sophisticated.
The following users liked this post:
tzoid9 (07-17-2019)
07-17-2019, 09:52 PM
#14
Le Mans Master
Wait if you floor it in D, it should downshift automatically. If it doesn't, something is wrong. Maybe go with the "newer" fluid GM recommends for the A8 or a reflash or updated software for the trans is a must??
Either or, it's a shame GM put such a flawed auto in these cars. I can only imagine how much more amazing it would be if they stuffed the ZF 8 speed that's used in the hellcats and other cars like bentley etc.
But dude your porsche is a totally different animal compared to our cars. Both cars are insanely fast but put the power down completely different.
The Z is more like metallica and porsche is more like mozart. Both amazing but mozart (porsche) is more refined and sophisticated.
Either or, it's a shame GM put such a flawed auto in these cars. I can only imagine how much more amazing it would be if they stuffed the ZF 8 speed that's used in the hellcats and other cars like bentley etc.
But dude your porsche is a totally different animal compared to our cars. Both cars are insanely fast but put the power down completely different.
The Z is more like metallica and porsche is more like mozart. Both amazing but mozart (porsche) is more refined and sophisticated.
The following users liked this post:
reasonable suspicion (08-20-2019)
07-18-2019, 09:18 AM
#15
If someone who loves to be scared of the car they're driving, one should drive or own a Z. But it's not very confidence inspiring. Knowing at any moment you can lose it and there goes your beautiful car.
After driving other cars with a more "planted" feel, like GTR's, AMG's etc, you realize the difference in technology and refinement (well the AWD from the GTR helps) that gives you confidence whenever you plant your right foot.
07-23-2019, 12:05 PM
#16
Heel & Toe
Thread Starter
As an update, I had the car in to do the suspension software upgrade and asked them about this issue. They inspected the car and said that it appears to be working correctly. I suppose 5th and 6th are relatively long and I can't expect to feel that much of a surge at moderately low rpms.
If anyone out there with an auto Z06 feels like testing their car, I'd love to hear your findings. If so, drive the car on the highway in 5th or 6th at 2500 rpm in manual shifting mode and Touring, and then pin the throttle for a few seconds. If your car is like mine, the exhaust valves will open and the car will make more noise, but it won't pull very hard at all. It would be great to confirm that they all feel a little anemic in that situation as it really would confirm that my car is operating correctly.
If anyone out there with an auto Z06 feels like testing their car, I'd love to hear your findings. If so, drive the car on the highway in 5th or 6th at 2500 rpm in manual shifting mode and Touring, and then pin the throttle for a few seconds. If your car is like mine, the exhaust valves will open and the car will make more noise, but it won't pull very hard at all. It would be great to confirm that they all feel a little anemic in that situation as it really would confirm that my car is operating correctly.
07-23-2019, 12:21 PM
#17
Melting Slicks
Member Since: Oct 2010
Location: Fair Oaks, California
Posts: 2,162
Received 335 Likes
on
243 Posts
2017 C7 of the Year Finalist
My exhaust valves open every 2nd turn of the crank.
When in stealth mode my exhaust butterfly valve opens at 3500 rpm.
Haven't tested your issue of 5th or 6th gear, but may I suggest try using "D" and see if pinning to the floor has a better result.
Then experiment from that point on.
When in stealth mode my exhaust butterfly valve opens at 3500 rpm.
Haven't tested your issue of 5th or 6th gear, but may I suggest try using "D" and see if pinning to the floor has a better result.
Then experiment from that point on.
Last edited by jaden61; 07-23-2019 at 12:21 PM.
07-23-2019, 02:20 PM
#18
Drifting
As an update, I had the car in to do the suspension software upgrade and asked them about this issue. They inspected the car and said that it appears to be working correctly. I suppose 5th and 6th are relatively long and I can't expect to feel that much of a surge at moderately low rpms.
If anyone out there with an auto Z06 feels like testing their car, I'd love to hear your findings. If so, drive the car on the highway in 5th or 6th at 2500 rpm in manual shifting mode and Touring, and then pin the throttle for a few seconds. If your car is like mine, the exhaust valves will open and the car will make more noise, but it won't pull very hard at all. It would be great to confirm that they all feel a little anemic in that situation as it really would confirm that my car is operating correctly.
If anyone out there with an auto Z06 feels like testing their car, I'd love to hear your findings. If so, drive the car on the highway in 5th or 6th at 2500 rpm in manual shifting mode and Touring, and then pin the throttle for a few seconds. If your car is like mine, the exhaust valves will open and the car will make more noise, but it won't pull very hard at all. It would be great to confirm that they all feel a little anemic in that situation as it really would confirm that my car is operating correctly.
You should never go WOT when you are in an overdrive gear in manual mode and just luging along. Downshift it and drive it like it was designed.
The following users liked this post:
tertiumquid (08-20-2019)
07-23-2019, 02:52 PM
#19
Safety Car
Ditto; I only read the first few posts before replying
If you're in manual mode and you want to pass someone, why aren't you downshifting? The engine does make a lot of low end torque but if your goal is to pass someone aggressively, or to put "bus lengths", then you're in the wrong gear, downshift.
Or leave it in D, and let the computer downshift for you. The paddles are useless on these cars. But then again the auto isn't exactly great either.
Or leave it in D, and let the computer downshift for you. The paddles are useless on these cars. But then again the auto isn't exactly great either.
All I did was punch it in "Drive" and I got to say I was impressed/surprised with the results, we were side by side when we both hit the throttle and I left him like he was sitting at a traffic light; all he saw was my tail lights getting smaller "Quick". I slowed up waiting to see if he wanted to go again but he took the next exit. 
Bottom Line:
Get rid of that V8/V4 mode & let the trans decide what gear is best.
I was not expecting a roll race, as a matter of fact that was my first. If your a roll racer they often use a different procedure.
Last edited by C7/Z06 Man; 07-23-2019 at 03:02 PM.
07-23-2019, 03:23 PM
#20
Pro
Member Since: Jul 2016
Location: N. San Diego-Fallbrook California
Posts: 698
Received 191 Likes
on
152 Posts
I have a stock tune 2015 Z06 with the A8 and an AFE CAI. Years ago I got rid of the V8/V4 mode which there are two ways I know of to do that and still keep your warranty. About a week ago I was cruising (approx. 60 mph) down the beltway in the slow lane minding my own business in tour mode when a Hellcat pulled up beside me and wanted to do battle. He punched it a few times trying to get me to bite, so I did. All I did was punch it in "Drive" and I got to say I was impressed/surprised with the results, we were side by side when we both hit the throttle and I left him like he was sitting at a traffic light; all he saw was my tail lights getting smaller "Quick". I slowed up waiting to see if he wanted to go again but he took the next exit.
Bottom Line:
Get rid of that V8/V4 mode & let the trans decide what gear is best.
I was not expecting a roll race, as a matter of fact that was my first. If your a roll racer they often use a different procedure.
All I did was punch it in "Drive" and I got to say I was impressed/surprised with the results, we were side by side when we both hit the throttle and I left him like he was sitting at a traffic light; all he saw was my tail lights getting smaller "Quick". I slowed up waiting to see if he wanted to go again but he took the next exit. Bottom Line:
Get rid of that V8/V4 mode & let the trans decide what gear is best.
I was not expecting a roll race, as a matter of fact that was my first. If your a roll racer they often use a different procedure.
