How effective is engine tuning when you get shipped the computer vs. tuning the car on site? Would it not be much more effective to tune the car on site? Or is the difference between tuning a car on site and tuning per a list of installed mods roughly negligible?

 

I've been reading All Corvettes are Red, a book that covers the development of the C5, and came across this.

"The accelerator pedal in C5 would be an anachronism. The Gen III would use ETC, electronic throttle control. The driver might think that his right foot was going pedal-to-the-metal, but ETC would be in the way....The computer would decide whether to obey, and sometimes it wouldn't"

 

Torque management mainly comes in during shifts and is limited to those torque levels "during shifts", it becomes more noticeable when there is allot of traction like at the track with drag radials, etc. The available LS2 tuning software that is out there and including LS2_edit (what we use) only has some of the TQ management tables that GM has in the C6.

Here are some tables found in a stock M6 C6.


"LS2 Edit Dump of Table -- 1st Gear Torque Limit - Ft. Lbs.

Filename = C:\LS2_edit\C6\2005\C6_b.LS2
500 600 700 800 900 1200 1500 2000 3000
Foot Pounds 85 89 104 111 126 148 185 244 281
"

"LS2 Edit Dump of Table -- 2nd Gear Torque Limit - Ft. Lbs.

Filename = C:\LS2_edit\C6\2005\C6_b.LS2
500 600 700 800 900 1200 1500 2000 3000
Foot Pounds 85 89 104 111 126 148 185 244 281

"
"LS2 Edit Dump of Table -- 3rd Gear Torque Limit - Ft. Lbs.

Filename = C:\LS2_edit\C6\2005\C6_b.LS2
500 600 700 800 900 1200 1500 2000 3000
Foot Pounds 85 89 104 111 126 148 185 244 281
"

"LS2 Edit Dump of Table -- 4th Gear Torque Limit - Ft. Lbs.

Filename = C:\LS2_edit\C6\2005\C6_b.LS2
500 600 700 800 900 1200 1500 2000 3000
Foot Pounds 85 89 104 111 126 148 185 244 281
"

"LS2 Edit Dump of Table -- 5th Gear Torque Limit - Ft. Lbs.

Filename = C:\LS2_edit\C6\2005\C6_b.LS2
500 600 700 800 900 1200 1500 2000 3000
Foot Pounds 85 89 104 111 126 148 185 244 281
"

"LS2 Edit Dump of Table -- 6th Gear Torque Limit - Ft. Lbs.

Filename = C:\LS2_edit\C6\2005\C6_b.LS2
500 600 700 800 900 1200 1500 2000 3000
Foot Pounds 85 89 104 111 126 148 185 244 281
"

Increasing the values of these tables and other tables in the software does not completely disable torque management. Case in point, our own M6 C6 would not have been able to go 10.94 @ 127+ MPH (it was the first C6 in the 10s and if I'm not mistaken it is still the quickest C6 out there even against nitrous, blowers and strokers) if it didn't have our torque management elimination module, when we shut it off the car only goes mid 11s.


HTH, Julio

 

A mail order tune based on a list of installed mods is not nearly as effective as an actual on site dyno tune, the shipped/mail order tune can only get the car 'in the ballpark' so to speak.

 

im wondering why you couldnt just "program" it out through the software (LS2 Edit, HP Tuners, etc.)? is it because these certain parameters arent available to change yet? I believe that there are more than just one area of TQ management but these software developers should be able to access them by now, especially knowing that this is the one main area most people are interested in. Hopefully the LS2 version of HP Tuners will have more to offer than the current version of LS2 Edit.

 

I know, but taking away throttle also prevents the mixture from going too lean on sudden acceleration demand, add fuel or restrict air, same result. The demand secondaries on a Quadrajet used to do a slightly similar thing. You could demand WOT, but the secondaries wouldn't let you have it until engine speed got high enough to support it. I know that's not the same thing, but the idea of avoiding a dangerous lean out on sudden acceleration is the same. And of course spark retard on loss of manifold vacuum served a similar purpose on the spark side of things.

Wait a minute, are you saying that this isn't transient behavior? In other words, at max demand at 4800 RPM the throttle would only be open to 72%? If so, the dyno curves I've seen still show 400 ft-lb flywheel at that point, not 281. I'm not saying you're wrong, it could be that the designers used this technique to flatten out the torque curve of the engine. But it has been my impression that TM was only active for transient events.

No question the relationship between the accelerator pedal and the throttle opening is non-linear, anyone who has driven these cars knows that.

I understand that the engine on average runs a lot of timing and a leaner mixture than we could get away with in carb days. That's why it can get such excellent fuel economy and make so much more power than the older engines without computer controls. I think that was my point. At sudden high demand in the mid-RPM range that can be too much, and risks destructive detonation. So the computer has to do something about it to protect the engine. I think that's what's being called TM.

It makes sense that if TM exists, it would be in the low to mid RPM range. That's where peak cylinder dynamic pressure can get out of hand. But this doesn't track with what you said you saw at torque peak RPM, which is well above the danger zone. By definition, torque peak occurs at max volumetric efficiency, ie when the engine is breathing best. If it breathes best at 72% throttle, that seems contradictory. Perhaps there is more going on here than meets the eye.

AFAIK the tables in the ECM aren't labeled from the factory. The labels are being supplied by the third party tuning software companies who've attempted to reverse engineer the ECM code. I have to wonder whether these labels are well chosen. Perhaps the intended function of this table is somewhat different than we think. Perhaps the "torque values" being reported by the third party software are something else as well. Your note that they don't match measured torque very well would seem to indicate that to be the case. I'd really like to see this engine on a water brake dyno so we could clearly separate steady state and transient behaviors.

 

It takes time to reverse engineer these ECMs, in the early days (80s) some uveproms were just 32k bytes or less, the C6 is 1meg, 32 times more code. There are some tables that haven't been figured out for the C5 yet and there are many tables that haven't been figured out on the C6. Reprogramming software for the C6 has a long way to go.


Julio

 

Is all of this info like Top Secret at GM or something? With the tens of thousands of members on this board, you would think that a GM engineer who knows the facts would or could be on here to take out the guessing. So is this protected info that they don't want anyone to know?

I personally believe TM exists in M6 cars based on my track experience. I gained .4 in the 1/8 mile by turning off BOTH TC and AH. Not saying that I know for sure it turns off TM some how but the difference was siginificant and the launches were identical other than the car falling on it's face off the line for a second if you didn't turn both TC and AH off. None of my runs had TC on.

I honestly believe that the car uses calculations similar to those that allow a GTech meter to function. (Remember, the car has a built in G-Meter, just look at your HUD). My theory in my case was that the car actually took my MPH (0 initially off the line) and compared that against the amount of G's being pulled and used that to detect the hard launch (at least the attempt) and backed off power to the engine. It was VERY noticeable. You can even see it falling on its face in the vid. After turning off both TC and AH it ran .4 quicker.

Also, what about the claims that people have had that the car runs much better after say 3000 miles or so. Makes sense. GM making sure you break the car it and don't beat it to death till everything is settled in. Just a thought.

I still say these cars are much smarter than we imagine.

 

Same here. Holding the button for 5 seconds until both AH/TC are off gives me at least .3 seconds in the 1/4 mile. Running it in any other mode including "TC off" or "competitive" causes me to run significantly slower. Having said that, I don't think turning both AH/TC off is the same as turning TM off.

I have wondered about this and think it is possible. Those doing the reverse engineering of the code may know better. I've always thought it was possible that these cars hold back some amount of power until some preset mileage and then open it all up, or open more in stages at certain mileages. The dramatic increase in acceleration that I started seeing after about 1500 miles seems like more than would come from just breaking in the engine! Then again, there are people dynoing these things with 50 miles on the ODO and 5000 miles on the ODO and they all seem to get about 340-350 RWHP regardless of mileage. I guess if GM was clever, they could "detect" the car being on a dyno by the front wheels not turning and remove the restrictions when that happens. It's also possible that the computer needs the front wheel/ABS sensors and/or the accelerometer for the TM to work and that's why we see 345 RWHP on the dyno but get them out on the street and they may only be putting down 320 RWHP when actually on the road accelerating.

Mike

 

Im going to head out now and try turning off everything to see if I feel a difference.Ive never even attempted it yet.Just tried competitive mode.

 

 

Took it for a spin with everything off.It did seem to be quicker by the shifts and right after shifting.Funny that I did a turnaround to find a clear road for a quarter mile and right at that point a cop was sitting in the spot where I was going to lay the smack down. I only took the car up to 65.

 

Interesting Julio. Would like to check out this module.

Yes Mailorder tuning is not as good as being there. We do have a good deal of experience and a very large library of files that have been dynotuned. For the most part I would say that our mail orders are 90% If we have an exact match for the parts used I would say 95%. The C6s so far are all VERY alike and that makes my job more consistent in power and setup. Also there are only a few different producers of components and I have tuned most of them. I do not have all the answers and am far from perfect, but I am very confident in tuning the C6s that we will make good power and it will be hard for anyone else to pull more power out of it.

The tables involving TM are being identified currently and dealt with. Not an easy solution but will be figured out as more information is revealed.

Shopdog you are a sharp dude. The values in the PCM are the stk values not inaccurate. When I first saw TM it was on an 01 vette and that was event I described. We were in 3rd gear in an A4 car the event lasted over 3sec under 100%TPS. Detonation isnt as frequent as you might think. They do not knock much from what I have seen at all. I do not believe that TM was designed to deter detonantion, I believe it was to make the drivetrain last. Imagine the TQ curve, now where you would have a hill you would have a plateau because the lack of TPS has taken out your peak TQ. I never said anything about the car breathing best @ 72% TPS I did say 4800RPM (peak TQ) .

And yes these cars are quite smart.
God Bless
Jeremy Formato

 

Sure thing, just email Dave at davebusch@cartek.net or call 908-317-4496 Monday-Friday 9:30 am- 6:00 pm EST.


Julio

 

Jeremy, I am interested in your tuning for an otherwise stock car. On my C5 I did the headers, new intake as well as a dyno tune, then I considered a H/C package as well as gears and torque converter.

However on my C6 (MN6) I would be more interested in just squeezing more juice out through tuning, especially ridding it of the TM that is always being debated as to whether it does really exist (I'm sure it does).

I wouldn't want to (drastically) affect drivability or mileage, but when it goes WOT, I don't want to leave anything on the table. What do you think?

Thx.

 

miaugi, sent pm

BTW tuning is only going to help driveability not harm it, when executed properly. You should be able to inc MPG when timing is added in the mid cruising RPMs and when the fuel trims are lined up.
Jeremy

 

anyone who is planning on getting there car tuned (LS2 Edit) should wait another week or so, there is another update coming soon. It is another torque mangement parameter.

 

Jeremy, thanks for taking the time to speak with me today even though I know you were up to your eyeballs.....I really appreciate your help and advice!

I believe you to be a competent tuner and I look forward to having you do a tune for me within the next couple of weeks....albeit only if I decide against moving into a Z06.....stay tuned (pun intended! ).

 

I've been thinking about this post, mainly the table being identified as "torque management".

i suspect that these tables are the "reduced engine power" table and not "torque management tables".

when was the last time you saw a car with 281 ft lbs of trq do 0-60 in 5 seconds or the 1/4 mile in 13 ?

i understand the discussion has focused on this being a "transient" behavior but i suspect this is incorrect. it makes more sense that this is actually the "reduced engine power" part of the program.

by programming these tables so the supposed "torque management" is outside the range would in essence allow one to blow his engine when/if it overheated or another fault was detected that would normally send it into reduced power.

i believe folks are making more of the black helicopter torque management than is actually there. i believe the only time torque management comes into play is when traction control is active. think about it. what actually happens when traction control activates ? doesn't it sound an awful lot like torque management ?

just my .02 cents. would love to get my hands on ls2 edit and take a look for myself.

 

"(from GM Press Release) Marking the sixth generation of its legacy, the 2005 Chevrolet Corvette delivers more power, passion and precision to reach a new standard of performance car excellence. ...

... Traction control initiates individual wheel braking and/or engine torque reduction after sensing excessive wheelspin."

http://www.seriouswheels.com/top-200...orvette-C6.htm