Off idle throttle response
Race Director
Joined: Jul 2007
Posts: 10,961
Likes: 2,643
From: Texas Hill Country
it has nothing to do with being too rich or too lean. the mixture does not change when you switch to track mode. the ECM demands more power from a lower throttle position.
I am quite sure people changed jets and metering rods and twisted distributors and flipped air lids and even tightened throttle cable slack in the 60s. today you do the same work on your laptop to adjust mixture, timing, and, yes, throttle cable slack.....in the form of Driver Demand manipulation.
nothing to cry or be concerned about. just adjust it like the true car guy you/we are/were.
I am quite sure people changed jets and metering rods and twisted distributors and flipped air lids and even tightened throttle cable slack in the 60s. today you do the same work on your laptop to adjust mixture, timing, and, yes, throttle cable slack.....in the form of Driver Demand manipulation.
nothing to cry or be concerned about. just adjust it like the true car guy you/we are/were.
Melting Slicks
Joined: Nov 2004
Posts: 2,592
Likes: 393
St. Jude Donor 05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17
it has nothing to do with being too rich or too lean. the mixture does not change when you switch to track mode. the ECM demands more power from a lower throttle position.
I am quite sure people changed jets and metering rods and twisted distributors and flipped air lids and even tightened throttle cable slack in the 60s. today you do the same work on your laptop to adjust mixture, timing, and, yes, throttle cable slack.....in the form of Driver Demand manipulation.
nothing to cry or be concerned about. just adjust it like the true car guy you/we are/were.
I am quite sure people changed jets and metering rods and twisted distributors and flipped air lids and even tightened throttle cable slack in the 60s. today you do the same work on your laptop to adjust mixture, timing, and, yes, throttle cable slack.....in the form of Driver Demand manipulation.
nothing to cry or be concerned about. just adjust it like the true car guy you/we are/were.
I would really like to fix it but I'm not going to chance voiding the warranty.
Melting Slicks
Joined: Nov 2004
Posts: 2,592
Likes: 393
St. Jude Donor 05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17
Race Director
Joined: Jul 2007
Posts: 10,961
Likes: 2,643
From: Texas Hill Country
Drifting
Joined: Sep 2013
Posts: 1,505
Likes: 13
I just wish you could select throttle response the same way you can lock in steering effort.
I will, however, probably get a Diablo just for its ability to adjust things like this. They also claim once removed its undetectable by GM's dealer tech system. Not sure I believe that but I know for sure systems like HP Tuners are detectable.
I will, however, probably get a Diablo just for its ability to adjust things like this. They also claim once removed its undetectable by GM's dealer tech system. Not sure I believe that but I know for sure systems like HP Tuners are detectable.
Race Director
Joined: Mar 2010
Posts: 16,014
Likes: 829
I have 500 miles on my 14 convert. manual transmission. Took museum delivery in March. Trailered the car home. Noticed a throttle response condition: during idle a quick jab to the throttle results in a loud vacuum noise and very little engine rpm response. If the revs are brought up a little prior to the throttle jab the condition is eliminated. This is an annoyance when driving in stop and go traffic and you are stopped on a minor slope and you stay on the brake to stop drift back then when you try to release the clutch and jab the throttle you get no response.
Any ideas?
Any ideas?
I realize how displeasing it can be when faced with an off-idle throttle concern like this, and though you're seeking thoughts and opinions, I would be happy to communicate this situation with the designated Customer Experience Manager at your preferred dealer if you feel an official diagnosis is necessary. Feel free to message us privately if you'd like to proceed, or discuss this situation further.
William R.
Chevrolet Customer Care
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Thread Starter
Heel & Toe
Joined: Jul 2014
Posts: 15
Likes: 0
From: Findlay Ohio
off idle throttle response
Been while since I've posted on this issue. I have been diligently attempting to find the real story. After a lot of guys on this site tried to tell me I didn't know how to drive the car I finally got the real scoop from a real Bow Tie Guy:
Dennis,
It was a pleasure to speak with you at the US Nationals. I have spoken to some of our calibration folks and the off throttle launch sag that you described is documented. It is something in the software set in the manual application only. He tells that the software guys are aware of it but at this time, there is no indication of when or if a fix will be available.
If I hear anymore, I will let you know. Sorry I do not have any better answers.
Thanks,
Blake Nye
Chevy Performance
As you can read there is a real problem with the ECM's on the stick cars.
Case is closed
Dennis,
It was a pleasure to speak with you at the US Nationals. I have spoken to some of our calibration folks and the off throttle launch sag that you described is documented. It is something in the software set in the manual application only. He tells that the software guys are aware of it but at this time, there is no indication of when or if a fix will be available.
If I hear anymore, I will let you know. Sorry I do not have any better answers.
Thanks,
Blake Nye
Chevy Performance
As you can read there is a real problem with the ECM's on the stick cars.
Case is closed
Instructor
Joined: Oct 2013
Posts: 136
Likes: 13
From: Tennessee
If I hear anymore, I will let you know. Sorry I do not have any better answers.
Blake Nye
Chevy Performance
Thanks for the info! My C7 M7 has the throttle lag too. I drive it in sport mode 99% of the time. I think I will get a tune after the warranty runs out. It does a lot of strange stuff while decellerating too. I guess its emissions related.
Blake Nye
Chevy Performance
Thanks for the info! My C7 M7 has the throttle lag too. I drive it in sport mode 99% of the time. I think I will get a tune after the warranty runs out. It does a lot of strange stuff while decellerating too. I guess its emissions related.
Advanced
Joined: Feb 2009
Posts: 67
Likes: 0
From: Westerville Ohio
I have a '15 Z51 MN7 with less than 200 miles. It has the same sucking noise as Desalve's Vette and others. Since it has such low miles I have not been tearing around town and have not noticed any deteriorated performance to date. I had wondered about the noise though. I have owned 2 other C6 Vetts. Both manual trans versions, one a regular coupe and the second a Z06. Neither one had an instant of throttle lag. They were ready immediately with full power NOW!! Keep me in the loop via PM's if GM comes up with a remedy. It is just an annoyance at this time. (Love the car.)
Team Owner
Joined: Sep 1999
Posts: 41,732
Likes: 1,718
From: Springfield MO
Probably something to do with emissions. My Z06 would hesitate slightly, and some times bog for a split second on an easy start in first gear, with very little throttle application. After I had new PRC265 aftermarket heads installed, and the shop had to redo the factory tune because of the increased airflow, the problem was corrected.
Thread Starter
Heel & Toe
Joined: Jul 2014
Posts: 15
Likes: 0
From: Findlay Ohio
off idle throttle response
The problem is more than a nuisance. It goes to the heart of drivability. The car is a terrific performer when you want to drive that way but when you need to tame it, city driving, it is difficult to drive. Especially in a condition when you have to prevent a roll back into a car stopped behind you. It is impossible to catch the car with the clutch when you quickly move your foot from brake to throttle. You simply don't have any engine power. And yes the "hill assist" is not active. When at BG for the caravan celebration I spoke to Harlan Charles about the problem. He indicated no awareness of it and after some discussion his solution was to use the emergency brake to hold the car and get some revs up to engage the clutch then the brake would release automatically. Good grief I pay over $70K for a car that I can't pull off a minor hill without a stall!
Pro
Joined: Jun 2014
Posts: 514
Likes: 105
From: Georgia
Desalve,
I realize how displeasing it can be when faced with an off-idle throttle concern like this, and though you're seeking thoughts and opinions, I would be happy to communicate this situation with the designated Customer Experience Manager at your preferred dealer if you feel an official diagnosis is necessary. Feel free to message us privately if you'd like to proceed, or discuss this situation further.
William R.
Chevrolet Customer Care
I realize how displeasing it can be when faced with an off-idle throttle concern like this, and though you're seeking thoughts and opinions, I would be happy to communicate this situation with the designated Customer Experience Manager at your preferred dealer if you feel an official diagnosis is necessary. Feel free to message us privately if you'd like to proceed, or discuss this situation further.
William R.
Chevrolet Customer Care
This is not an isolated issue, it is common to all the manual transmission C7s.
Instead of dealing with isolated customers, find out what or if GM plans on doing about it. Probably a simple software change if they are inclined to provide some customer service.
Thanks
Lance
Race Director
Joined: May 2008
Posts: 10,742
Likes: 629
From: Manheim Pennsylvania
5th Gear
Joined: Nov 2011
Posts: 5
Likes: 0
From: Stony Point NC
I hear a "whoosh" sound in my manual C7 but have not noticed a real lag when accelerating from a stop in slow conditions. Or any time you "blip" the throttle it can be heard. I do keep mine in sport most of the time, using tour or eco only on the interstate. I thought the sound was due to direct injection, and my dealer as well as Harlen Charles (at the Caravan) said the same.
Drifting
Joined: Nov 2002
Posts: 1,692
Likes: 207
From: Loveland, CO
I realize most of this discussion has been related to the manual transmission. I have the auto and I am also disappointed with the off-idle response. It is embarrassing. I know some have stated that in the Track Mode things are better, but how many want to drive on the street in the Track Mode.
Maybe we could get GM to offer a "double pumper" carb. option.
Ralph
Maybe we could get GM to offer a "double pumper" carb. option.
Ralph
Team Owner
Joined: Sep 1999
Posts: 41,732
Likes: 1,718
From: Springfield MO
I realize most of this discussion has been related to the manual transmission. I have the auto and I am also disappointed with the off-idle response. It is embarrassing. I know some have stated that in the Track Mode things are better, but how many want to drive on the street in the Track Mode.
Maybe we could get GM to offer a "double pumper" carb. option.
Ralph
Maybe we could get GM to offer a "double pumper" carb. option.
Ralph