when the computer is off the computer is OFF! 
[Z06] 2001 Z06 Torque Management
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Burning Brakes
Joined: Nov 2006
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From: Goose Creek SC
I agree that there is a rev limit table for each gear (I've seen it too) ... but I wonder if/how the PCM uses it. Two examples:
* I'm driving down the freeway at 60 MPH in 6th gear (approx 1500 RPM in my car) and I see traffic slowing ahead. I slide the gearshift to neutral and let the engine revs fall to about 800 RPM while the car is still rolling at 55 to 60... what gear does the PCM think I'm in now ??? Am I in neutral, or do I have 5th selected and have just not let the clutch engage yet?? What RPM limit should the PCM assume in this case ( the PCM does not know clutch pedal state - only time status is checked is at engine start when the pedal has to be all the way to the floor to override the starter interlock) if I suddenly floor the accelerator pedal, the 5th gear limit, or the 6th gear limit, ???
* I've got Autotap, and every time I've asked it to display "gear selected" for my manual box, it shows 3rd, regardless of the actual gear the car is in. Maybe that's a fault in my version of the Autotap software, but I have yet to see the PCM actually "know" what gear I'm in. My bet is, though, 3rd is the PCM default that it lives by.
I'd think that it is just pointless in a manual car for the PCM to worry about what gear the car is in. Heck, if I'm doing 80 MPH and downshift to 1st gear, there is not a thing the PCM can do to protect the engine ... it can't change gears, disengage the clutch, or even ask the EBCM to brake fast enough to stop an over-rev. Also, I've always wondered why the PCM has that table for a manual car, as what would be the point of setting, say, a 4000 RPM limit for 2nd gear and a 6000 RPM limit for 3rd gear ?? I suspect the table is there for automatic vehicles, and the fact it has 6 gears defined was a software decision to support up to 6 even though the C5 automatics only have 4. Saves re-writing software (and managing multiple versions in different cars) if a later switch is made to a 5 or 6 speed automatic gearbox.
I agree the PCM could (and based on the RPM limit table) should, be figuring out what gear the car is in, but I have yet to see an example of the PCM actually doing this. If it was important for the PCM to know what gear was selected, a sensor would make a whole lot more sense than "guestimating" what gear is .. or might be ... selected.
* I'm driving down the freeway at 60 MPH in 6th gear (approx 1500 RPM in my car) and I see traffic slowing ahead. I slide the gearshift to neutral and let the engine revs fall to about 800 RPM while the car is still rolling at 55 to 60... what gear does the PCM think I'm in now ??? Am I in neutral, or do I have 5th selected and have just not let the clutch engage yet?? What RPM limit should the PCM assume in this case ( the PCM does not know clutch pedal state - only time status is checked is at engine start when the pedal has to be all the way to the floor to override the starter interlock) if I suddenly floor the accelerator pedal, the 5th gear limit, or the 6th gear limit, ???
* I've got Autotap, and every time I've asked it to display "gear selected" for my manual box, it shows 3rd, regardless of the actual gear the car is in. Maybe that's a fault in my version of the Autotap software, but I have yet to see the PCM actually "know" what gear I'm in. My bet is, though, 3rd is the PCM default that it lives by.
I'd think that it is just pointless in a manual car for the PCM to worry about what gear the car is in. Heck, if I'm doing 80 MPH and downshift to 1st gear, there is not a thing the PCM can do to protect the engine ... it can't change gears, disengage the clutch, or even ask the EBCM to brake fast enough to stop an over-rev. Also, I've always wondered why the PCM has that table for a manual car, as what would be the point of setting, say, a 4000 RPM limit for 2nd gear and a 6000 RPM limit for 3rd gear ?? I suspect the table is there for automatic vehicles, and the fact it has 6 gears defined was a software decision to support up to 6 even though the C5 automatics only have 4. Saves re-writing software (and managing multiple versions in different cars) if a later switch is made to a 5 or 6 speed automatic gearbox.
I agree the PCM could (and based on the RPM limit table) should, be figuring out what gear the car is in, but I have yet to see an example of the PCM actually doing this. If it was important for the PCM to know what gear was selected, a sensor would make a whole lot more sense than "guestimating" what gear is .. or might be ... selected.
There is also a rev limit for neautral. In fact, there are two rev limit tables, all based on gear selection and neautral. One rev limit is a fuel shut off, and the other is an Electronic throttle control (ETC) limiter. All gear positions use the fuel cut-off except for 5th gear. 5th gear uses the ETC limiter so when you do a top speed run in 5th gear, you're not stuttering on the fuel cut-off.
Here are the both rev limit tables:
Hammer
Le Mans Master
Joined: Dec 2006
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From: Phoenix Arizona
There is also a rev limit for neautral. In fact, there are two rev limit tables, all based on gear selection and neautral. One rev limit is a fuel shut off, and the other is an Electronic throttle control (ETC) limiter. All gear positions use the fuel cut-off except for 5th gear. 5th gear uses the ETC limiter so when you do a top speed run in 5th gear, you're not stuttering on the fuel cut-off.
Here are the both rev limit tables:
Hammer
Here are the both rev limit tables:
Hammer
Safety Car
Joined: Aug 2000
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From: San Rafael CA
Hammer,
Have you actually tried altering the rev limit table to see if it makes a difference ?? For kicks, and to stay legal speed wise while testing, alter the table for second gear and set the limit to, say, 1500 RPM. I'd be quite surprised if the car actually "hit the limit" ... I bet it'll go to your "default" limit of 6500 in second ... please try it and let us know. I'd do mine but the car is on jack stands right now as I've been rebuilding the calipers front and rear ... a project that is SUPPOSED to wrap up this weekend.
As I said before, my Autotap shows 3rd as the selected gear, so alter the limit for 2nd only.
Looking forward to the results of your experiment ...
Steve
Have you actually tried altering the rev limit table to see if it makes a difference ?? For kicks, and to stay legal speed wise while testing, alter the table for second gear and set the limit to, say, 1500 RPM. I'd be quite surprised if the car actually "hit the limit" ... I bet it'll go to your "default" limit of 6500 in second ... please try it and let us know. I'd do mine but the car is on jack stands right now as I've been rebuilding the calipers front and rear ... a project that is SUPPOSED to wrap up this weekend.
As I said before, my Autotap shows 3rd as the selected gear, so alter the limit for 2nd only.
Looking forward to the results of your experiment ...
Steve
Burning Brakes
Joined: Nov 2006
Posts: 1,071
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From: Goose Creek SC
Hammer
Burning Brakes
Joined: Nov 2006
Posts: 1,071
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From: Goose Creek SC
Hammer,
Have you actually tried altering the rev limit table to see if it makes a difference ?? For kicks, and to stay legal speed wise while testing, alter the table for second gear and set the limit to, say, 1500 RPM. I'd be quite surprised if the car actually "hit the limit" ... I bet it'll go to your "default" limit of 6500 in second ... please try it and let us know. I'd do mine but the car is on jack stands right now as I've been rebuilding the calipers front and rear ... a project that is SUPPOSED to wrap up this weekend.
As I said before, my Autotap shows 3rd as the selected gear, so alter the limit for 2nd only.
Looking forward to the results of your experiment ...
Steve
Have you actually tried altering the rev limit table to see if it makes a difference ?? For kicks, and to stay legal speed wise while testing, alter the table for second gear and set the limit to, say, 1500 RPM. I'd be quite surprised if the car actually "hit the limit" ... I bet it'll go to your "default" limit of 6500 in second ... please try it and let us know. I'd do mine but the car is on jack stands right now as I've been rebuilding the calipers front and rear ... a project that is SUPPOSED to wrap up this weekend.
As I said before, my Autotap shows 3rd as the selected gear, so alter the limit for 2nd only.
Looking forward to the results of your experiment ...
Steve
I know it has been done that the fuel cut-off rev limiter has been kept the same as stock in all gears, but the ETC limiter has been raised so Z06's can have even more top speed which is done in 5th gear.
Hammer
Drifting
Joined: Dec 2005
Posts: 1,822
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From: Dayton, OH
You don't understand! When the computer is "off" it's only less intrusive! It's still managing torque in order to protect the drivetrain. This applies to automatics, 6 speeds and Z06. Regardless, they all have torque managment even when traction control is off!
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Drifting
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From: Dayton, OH
????????????
Safety Car
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From: San Rafael CA
And your statement is based on what ??
The FACT is that the Torque Management algorithm needs input from the "torque Converter" ....and where is that located on a Z06 ???
Please EXPLAIN when/how the PCM does Torque Management on a Z06 ????
Le Mans Master
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From: Phoenix Arizona
Burning Brakes
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From: Goose Creek SC
Safety Car
Joined: Aug 2000
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From: San Rafael CA
I have not done it, but I may. But here's the thing, how does the PCM know you are in 5th gear to only use the soft ETC limiter? There is no 5th gear position sensor. So obviously it has to be able to know gear position based on a speed and rpm algorithm.
I know it has been done that the fuel cut-off rev limiter has been kept the same as stock in all gears, but the ETC limiter has been raised so Z06's can have even more top speed which is done in 5th gear.
Hammer
I know it has been done that the fuel cut-off rev limiter has been kept the same as stock in all gears, but the ETC limiter has been raised so Z06's can have even more top speed which is done in 5th gear.
Hammer
I agree it is POSSIBLE the PCM could calculate the gear you're in, and use that for the rev limiter function .... BUT ....
Going back to the original issue of "Torque Management" .... even IF the car knew which gear I'm in, that's only two of three required inputs to the TM algorithm. Still missing torque converter status. Also, the PCM cannot sense when I'm changing gears as most of us shift without depressing the pedal to the floor far enough to hit the starter interlock switch. At best the PCM would recognize a gear change AFTER it is completed (by seeing the new engine speed versus road speed and calculating what gear I'm in now) , and a large part of TM is meant to "protect" the drivetrain DURING a shift. Works great on an automatic because it is the PCM that decides when a shift is to occur and manages and monitors the shift itself. It is a USELESS function on a manual car.
Just as the rev limiter can't prevent an over-rev if I'm doing 80 MPH and I select 1st gear, TM (especially without a sensor in the tranny to know what gear is selected, or being selected) CANNOT figure out if I'm shifting up, or down a gear, or even when the shift is occuring.
TM was first introduced on Caddy's back IIRC in the 1990s as a way to make shifts feel "smoother". The idea was to momentarily reduce engine torque as a shift occured, first to lower stress in the gearbox, and then to allow the torque to "ramp up" after the shift so even under hard acceleration a shift would "feel" smooth. A side benefit is less strain on the drivetrain.
If TM really did work in a Z06, how come you can break the rear tires loose EASILY in a 1st to 2nd shift (even with TC on, though that will then intervene pretty quickly) ?? In some cases, you can bust them loose on a 2nd to 3rd shift.
GM lets (at least a C5 Z06 driver - they've built more "nanny" crap into the C6 PCM) you be as "abusive" as you dare be with the drivetrain. I have NEVER experienced ANY engine hesitation or loss of power on-track, or on the street. As another poster said earlier .... TM is your right foot.
Sorry,
Last edited by BlackZ06; Apr 1, 2007 at 12:59 PM. Reason: fix typo
Drifting
Joined: Dec 2005
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From: Dayton, OH
BlackZ06 stated,
If TM really did work in a Z06, how come you can break the rear tires loose EASILY in a 1st to 2nd shift (even with TC on, though that will then intervene pretty quickly) ?? In some cases, you can bust them loose on a 2nd to 3rd shift.
Torque management as you stated earlier is not Traction Control.
The reason you can break the tires loose in first and second is:
1st Torque multiplication of the transmission
2nd Overcoming the coefficient of friction of the tires
Torque managment reduces the amount of torque/power the engine is allowed to produce on/during upshifts (6spd AND Auto) in order to protect the drivetrain. It REDUCES the torque/power not stops it completely. As the first poster stated, if you remove torque managment it will break loose MUCH easier! If you have any 6spd C5 or C6 corvette and have a good tuner remove TM it's like a different car
If TM really did work in a Z06, how come you can break the rear tires loose EASILY in a 1st to 2nd shift (even with TC on, though that will then intervene pretty quickly) ?? In some cases, you can bust them loose on a 2nd to 3rd shift.
Torque management as you stated earlier is not Traction Control.
The reason you can break the tires loose in first and second is:
1st Torque multiplication of the transmission
2nd Overcoming the coefficient of friction of the tires
Torque managment reduces the amount of torque/power the engine is allowed to produce on/during upshifts (6spd AND Auto) in order to protect the drivetrain. It REDUCES the torque/power not stops it completely. As the first poster stated, if you remove torque managment it will break loose MUCH easier! If you have any 6spd C5 or C6 corvette and have a good tuner remove TM it's like a different car
Last edited by geerookie; Apr 3, 2007 at 05:37 AM. Reason: clarify and correct hammer/BlackZ06
Burning Brakes
Joined: Nov 2006
Posts: 1,071
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From: Goose Creek SC
Hammer stated,
If TM really did work in a Z06, how come you can break the rear tires loose EASILY in a 1st to 2nd shift (even with TC on, though that will then intervene pretty quickly) ?? In some cases, you can bust them loose on a 2nd to 3rd shift.
Torque management as you stated earlier is not Traction Control.
The reason you can break the tires loose in first and second is:
1st Torque multiplication of the transmission
2nd Overcoming the coefficient of friction of the tires
Torque managment reduces the amount of torque/power the engine is allowed to produce on/during upshifts (6spd AND Auto) in order to protect the drivetrain. It REDUCES the torque/power not stops it completely. As the first poster stated, if you remove torque managment it will break loose MUCH easier! If you have any 6spd C5 or C6 corvette and have a good tuner remove TM it's like a different car
If TM really did work in a Z06, how come you can break the rear tires loose EASILY in a 1st to 2nd shift (even with TC on, though that will then intervene pretty quickly) ?? In some cases, you can bust them loose on a 2nd to 3rd shift.
Torque management as you stated earlier is not Traction Control.
The reason you can break the tires loose in first and second is:
1st Torque multiplication of the transmission
2nd Overcoming the coefficient of friction of the tires
Torque managment reduces the amount of torque/power the engine is allowed to produce on/during upshifts (6spd AND Auto) in order to protect the drivetrain. It REDUCES the torque/power not stops it completely. As the first poster stated, if you remove torque managment it will break loose MUCH easier! If you have any 6spd C5 or C6 corvette and have a good tuner remove TM it's like a different car
Hammer
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
Hammer stated,
If TM really did work in a Z06, how come you can break the rear tires loose EASILY in a 1st to 2nd shift (even with TC on, though that will then intervene pretty quickly) ?? In some cases, you can bust them loose on a 2nd to 3rd shift.
Torque management as you stated earlier is not Traction Control.
The reason you can break the tires loose in first and second is:
1st Torque multiplication of the transmission
2nd Overcoming the coefficient of friction of the tires
Torque managment reduces the amount of torque/power the engine is allowed to produce on/during upshifts (6spd AND Auto) in order to protect the drivetrain. It REDUCES the torque/power not stops it completely. As the first poster stated, if you remove torque managment it will break loose MUCH easier! If you have any 6spd C5 or C6 corvette and have a good tuner remove TM it's like a different car
If TM really did work in a Z06, how come you can break the rear tires loose EASILY in a 1st to 2nd shift (even with TC on, though that will then intervene pretty quickly) ?? In some cases, you can bust them loose on a 2nd to 3rd shift.
Torque management as you stated earlier is not Traction Control.
The reason you can break the tires loose in first and second is:
1st Torque multiplication of the transmission
2nd Overcoming the coefficient of friction of the tires
Torque managment reduces the amount of torque/power the engine is allowed to produce on/during upshifts (6spd AND Auto) in order to protect the drivetrain. It REDUCES the torque/power not stops it completely. As the first poster stated, if you remove torque managment it will break loose MUCH easier! If you have any 6spd C5 or C6 corvette and have a good tuner remove TM it's like a different car
We're talking about a Z06 with a MANUAL transmission ...... please go read how a torque converter (found on an AUTOMATIC transmission) works and how it multiplies torque ... and then please come back and explain ....
* How a manual transmission "multiplies torque" ...
* How the PCM "knows" you're shifting the gears of a MANUAL gearbox .. what sensors tell it when the shift is occuring, and are you shifting up/down the gearbox ??? The PCM is a computer, it does what it is programmed to do when it has "input" ... without input it cannot make decisions on its own. Computers don't "react" to zero inputs. In other words .... how would the PCM know I'm doing an upshift versus a downshift, or even that a shift is occurring ???
Last edited by BlackZ06; Apr 2, 2007 at 07:51 AM.
Drifting
Joined: Dec 2005
Posts: 1,822
Likes: 1
From: Dayton, OH
Drifting
Joined: Dec 2005
Posts: 1,822
Likes: 1
From: Dayton, OH
Torque multiplication of the transmission ?!?!?!?!
We're talking about a Z06 with a MANUAL transmission ...... please go read how a torque converter (found on an AUTOMATIC transmission) works and how it multiplies torque ... and then please come back and explain ....
* How a manual transmission "multiplies torque" ...
* How the PCM "knows" you're shifting the gears of a MANUAL gearbox .. what sensors tell it when the shift is occuring, and are you shifting up/down the gearbox ??? The PCM is a computer, it does what it is programmed to do when it has "input" ... without input it cannot make decisions on its own. Computers don't "react" to zero inputs. In other words .... how would the PCM know I'm doing an upshift versus a downshift, or even that a shift is occurring ???
We're talking about a Z06 with a MANUAL transmission ...... please go read how a torque converter (found on an AUTOMATIC transmission) works and how it multiplies torque ... and then please come back and explain ....
* How a manual transmission "multiplies torque" ...
* How the PCM "knows" you're shifting the gears of a MANUAL gearbox .. what sensors tell it when the shift is occuring, and are you shifting up/down the gearbox ??? The PCM is a computer, it does what it is programmed to do when it has "input" ... without input it cannot make decisions on its own. Computers don't "react" to zero inputs. In other words .... how would the PCM know I'm doing an upshift versus a downshift, or even that a shift is occurring ???
http://www.team-integra.net/sections...?ArticleID=707
The computer calculates the gear you are in based on wheel speed and engine RPM and and if the clutch is or is not engaged. Based on these inputs it makes a logical decision.
Safety Car
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From: Minburn Ia
Torque Management .... is not turned off by turning off T/C.
TM pulls timing and cuts fuel to engine ... when computer tells it to.
TM ... must be turned off via reprogram of computer.
Do a thead search of this topic ....
Many have been confused by the pseudo experts who have claimed to know that it doesn't apply to 6-speeds.
Ask Ranger if you still have doubts .... his C6Z has TM ... and he wishes it didn't.
TM pulls timing and cuts fuel to engine ... when computer tells it to.
TM ... must be turned off via reprogram of computer.
Do a thead search of this topic ....
Many have been confused by the pseudo experts who have claimed to know that it doesn't apply to 6-speeds.
Ask Ranger if you still have doubts .... his C6Z has TM ... and he wishes it didn't.