Takeoff Hesitation
Thread Starter
7th Gear
Joined: Apr 2005
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Takeoff Hesitation
My C6 A4 has 1000 miles on it now. I followed the owners manual advise about "no full throttle takeoffs" before 500 miles. Well, since then I have attempted 4 full throttle takeoffs from a dead stop and I feel a very noticeable hesitation at the start. Its almost best described as a bog....like its not able to handle the fuel all at once. I tried doing it with the traction control off but it didnt seem to help. I test drove a new C6 with the standard ratio gear before I ordered mine and it really put me back in the seat from a dead start. This was a car on the dealers lot with less than 10 miles on the odometer. I ordered mine with the performance ratio thinking it would be that much better. I'm disapointed. Before I take it to the dealer (which I hate to do with any of my cars) I thought I would ask if anyone else has had this problem. Thanks
Melting Slicks
Joined: Feb 2005
Posts: 2,179
Likes: 97
From: Palm Coast, FL
I don't have any answers for you but funny you brought this up: I too have an A4 but with only 226 miles on it. However, even this this should have nothing to do with your problem, I will wait till I have 1500-2000 miles before I do any full throtle starts-thats just my way of braking in a new car. I sure hope I don't experience this problem because mine came thru with a 2:73 axle ratio gears and I am planning to change the whole carrier out thur the dealer for a 3:42 and I sure hope it doesn't bog my auto either. Now I'm a bit concerned. Sounds like you should bring the car to the dealer; no new car should bog down and should start like the other dealer car you tested, I would think. Good Luck and I'll be watching this post for other ideas and thoughts and how you resolve your problem.
Sal
Sal
Drifting
Joined: Oct 2003
Posts: 1,945
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From: Salinas Ca.
I have the A4 with the 3.15 axle. This is only my second day driving the car and I have less than 50 miles on it. I came down a freeway on-ramp today. There was no traffic so I put my foot into it. It took off very well, but after about 1 second it seemed to kick into another gear and take me to warp speed in an instant. It was a great feeling but I wonder why the slight delay?
Race Director
Joined: Oct 2004
Posts: 10,089
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Originally Posted by benspruce
I have the A4 with the 3.15 axle. This is only my second day driving the car and I have less than 50 miles on it. I came down a freeway on-ramp today. There was no traffic so I put my foot into it. It took off very well, but after about 1 second it seemed to kick into another gear and take me to warp speed in an instant. It was a great feeling but I wonder why the slight delay?
Cruising
Joined: Jun 2005
Posts: 10
Likes: 1
Im thinking this is related to the TM (torque management) that people are talking about... read here >>> http://forums.corvetteforum.com/show...8&forum_id=101
Burning Brakes
Joined: Apr 2005
Posts: 973
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St. Jude Donor '08
Why baby these cars for 500-1000 miles. Enjoy it and drive it like you stole it after the oil temp ( not coolant temp) has hit operating temperature. Seal those rings from the start. Aluminum engines are different alloys for different parts, it is extremely important that all components are up to temp before load. These are not 1000 pound steel big blocks that are indestructible and heavy and overengineered with steel.
Le Mans Master
Joined: Dec 2003
Posts: 7,457
Likes: 144
From: NC
It is definately Torque Management. even my 6-spd Z51 car detects a hard take off and backs off the engine for a sec. Translates as feeling like it is bogging out and then takes off. hold the active handling button for 5+ secs till you get the message in the DIC saying both Active Handling and Traction control turned off and then try it.
Team Owner
Joined: Feb 2000
Posts: 53,520
Likes: 77
From: Arizona
Originally Posted by stabori
Why baby these cars for 500-1000 miles. Enjoy it and drive it like you stole it after the oil temp ( not coolant temp) has hit operating temperature. Seal those rings from the start. Aluminum engines are different alloys for different parts, it is extremely important that all components are up to temp before load. These are not 1000 pound steel big blocks that are indestructible and heavy and overengineered with steel.
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Team Owner
Joined: Feb 2000
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From: Arizona
Originally Posted by cerino2000
It is definately Torque Management. even my 6-spd Z51 car detects a hard take off and backs off the engine for a sec. Translates as feeling like it is bogging out and then takes off. hold the active handling button for 5+ secs till you get the message in the DIC saying both Active Handling and Traction control turned off and then try it.
Le Mans Master
Joined: Dec 2003
Posts: 7,457
Likes: 144
From: NC
Originally Posted by Hoonose
Geez, I don't think my 6 spd Z51 does that, even with T/C left on. Maybe I'm easing the clutch in, as opposed to dumping it all at once.
Race Director
Joined: Oct 2004
Posts: 10,089
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Originally Posted by cerino2000
Actually I tried many different ways. Dumping it was not a good thing....easing it (out within a second though) was fine but it would fall on it's face consistently...in fact, every time. (i have the vids posted on the forum somewhere). As soon as I turned everything off, I instantly ran .4 quicker in the 1/8th. Launching technique did not change. Starting that night, I ran about 8 passes and not a single one fell on it's face. Huge difference. I was shocked as I didn't think 6-spds had torque management. I am a believer now.
TM involves the computer backing off timing and throttle opening when it detects excessive torque production. Apparently it reads the ABS wheel speed sensors to make this measurement. Knowing the rate of acceleration, the gear ratio, and the weight of the car, it can calculate how much torque is being produced to generate that much acceleration (same thing a dyno does). If that figure exceeds a factory preset amount, it steps in and retards timing and throttle opening. The ECM also retards spark during shifts, to avoid engine and drivetrain damage. That's generally desireable, since the car is operating between gears and isn't providing any useful acceleration while shifting anyway.
Le Mans Master
Joined: Dec 2003
Posts: 7,457
Likes: 144
From: NC
All of the previous runs were in competitive driving mode which always allowed some wheel spin. I even heated the tires up a little bit prior to a few runs, in competitive driving mode, and the car never shut it down. It was only on hard launches off the line, not really with wheel spin, that it had 'the bog'.
I can't quite say what was causing it to fall on its face. I am at a loss for an explanation. Most of those launches had minimal wheel spin and certainly less than when i was heating the tires. As soon as I turned everything off, the 'fall on your face' syndrome disappeared. Not sure why, but it was without a doubt gone.
This is exactly what the car acted like on launch without everything turned off.
I can't quite say what was causing it to fall on its face. I am at a loss for an explanation. Most of those launches had minimal wheel spin and certainly less than when i was heating the tires. As soon as I turned everything off, the 'fall on your face' syndrome disappeared. Not sure why, but it was without a doubt gone.
Apparently it reads the ABS wheel speed sensors to make this measurement. Knowing the rate of acceleration, the gear ratio, and the weight of the car, it can calculate how much torque is being produced to generate that much acceleration (same thing a dyno does). If that figure exceeds a factory preset amount, it steps in and retards timing and throttle opening.
Last edited by cerino2000; Jul 1, 2005 at 07:20 PM.
Safety Car
Joined: Jun 2005
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From: DFW This user does not support or recommend the product or service displayed in the ad to the right
Originally Posted by stabori
Why baby these cars for 500-1000 miles. Enjoy it and drive it like you stole it after the oil temp ( not coolant temp) has hit operating temperature. Seal those rings from the start. Aluminum engines are different alloys for different parts, it is extremely important that all components are up to temp before load. These are not 1000 pound steel big blocks that are indestructible and heavy and overengineered with steel.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Originally Posted by cerino2000
It is definately Torque Management. even my 6-spd Z51 car detects a hard take off and backs off the engine for a sec. Translates as feeling like it is bogging out and then takes off. hold the active handling button for 5+ secs till you get the message in the DIC saying both Active Handling and Traction control turned off
So you turned off AH and TCS by using the button. What makes you think it also disabled the TM system ?
Le Mans Master
Joined: Dec 2003
Posts: 7,457
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From: NC
Originally Posted by Mike Mercury
There are TCS (Traction Control), AH (Active Handling), and TM (Torque Management) systems on the car. All have their own unique duties.
So you turned off AH and TCS by using the button. What makes you think it also disabled the TM system ?
So you turned off AH and TCS by using the button. What makes you think it also disabled the TM system ?
It made sense afterwards. The way I see it, the car measured the amount of G force the car was displaying vs how fast I was going (0 at the very start) and used that to determine I was launching very hard. To keep me from tearing up the car, it backed off the power to the engine until it (TM) determined that it was ok to give it back.
Could be wrong, but .4 in the 1/8th doesn't lie.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
if the C6 is anything like the C5, then there are three modes available via the DIC - and they only affect 2 of the 3 systems (AH, TCS, TM) I previously mentioned:
mode 1. AH & TC on (startup mode)
mode 2. AH on, TC off (Competitive Driving; activated by holding the button down for about 6 seconds)
mode 3. AH off, TC off (quick button push)
Neither of these modes disables or even alters the Torque Management system though.
There's much for us to relearn with the new C6; but a lot of it's PCM operation is almost exactly the same as the 2001 & newer C5.
mode 1. AH & TC on (startup mode)
mode 2. AH on, TC off (Competitive Driving; activated by holding the button down for about 6 seconds)
mode 3. AH off, TC off (quick button push)
Neither of these modes disables or even alters the Torque Management system though.
There's much for us to relearn with the new C6; but a lot of it's PCM operation is almost exactly the same as the 2001 & newer C5.
Drifting
Joined: Jan 2001
Posts: 1,326
Likes: 47
From: Tullahoma, TN
I test drove a couple 05 autos, both with 3:15s and the kickdown worked fine and from a dead stop; great response so I don't think your problem could be considered normal. Something is wrong.
Pro
Joined: Sep 2004
Posts: 678
Likes: 0
From: Winchester VA
Originally Posted by Mike Mercury
if the C6 is anything like the C5, then there are three modes available via the DIC - and they only affect 2 of the 3 systems (AH, TCS, TM) I previously mentioned:
mode 1. AH & TC on (startup mode)
mode 2. AH on, TC off (Competitive Driving; activated by holding the button down for about 6 seconds)
mode 3. AH off, TC off (quick button push)
Neither of these modes disables or even alters the Torque Management system though.
There's much for us to relearn with the new C6; but a lot of it's PCM operation is almost exactly the same as the 2001 & newer C5.
mode 1. AH & TC on (startup mode)
mode 2. AH on, TC off (Competitive Driving; activated by holding the button down for about 6 seconds)
mode 3. AH off, TC off (quick button push)
Neither of these modes disables or even alters the Torque Management system though.
There's much for us to relearn with the new C6; but a lot of it's PCM operation is almost exactly the same as the 2001 & newer C5.
I tried launches in full-on mode (TC & AH on), Competive Mode, and all systems off. I had a passenger that screamed WOW when we did the launch with all systems off...he said it felt like a different car, and pushed him back in his seat with much more force!
I don't take systems off when i'm driving hard through the twisties... but when i want the hardest launch (straight line stuff only), i take all systems off and there IS a difference.
Last edited by C64BC; Jul 16, 2005 at 11:52 AM.
